© Goodheart-Willcox Co., Inc. (12 Topics) Cooling system diagnosis Cooling system problems Water pump service Thermostat service Cooling system hose service Radiator and pressure cap service © Goodheart-Willcox.

Transcript © Goodheart-Willcox Co., Inc. (12 Topics) Cooling system diagnosis Cooling system problems Water pump service Thermostat service Cooling system hose service Radiator and pressure cap service © Goodheart-Willcox.

Slide 1

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 2

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 3

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 4

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 5

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 6

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 7

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 8

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 9

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 10

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 11

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 12

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 13

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 14

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 15

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 16

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 17

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 18

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 19

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 20

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 21

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 22

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 23

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 24

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 25

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 26

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 27

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 28

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 29

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 30

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 31

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 32

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 33

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 34

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 35

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 36

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 37

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 38

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 39

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 40

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 41

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 42

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 43

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 44

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 45

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 46

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 47

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 48

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 49

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 50

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 51

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 52

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 53

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 54

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 55

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 56

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 57

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 58

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 59

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 60

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 61

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 62

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 63

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 64

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 65

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 66

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

Slide 67

© Goodheart-Willcox Co., Inc.

(12 Topics)

Cooling system diagnosis
Cooling system problems
Water pump service
Thermostat service
Cooling system hose service
Radiator and pressure cap service

© Goodheart-Willcox Co., Inc.

Fan belt service
Engine fan service
Freeze plug service
Coolant service
Flushing a cooling system
Temperature gauge service

© Goodheart-Willcox Co., Inc.

 Gather information:
Talk to the owner or service writer to find out as
much as possible about the symptoms
A Cooling System Diagnosis Chart in the
service manual can be very helpful when
problems are difficult to locate and correct.

© Goodheart-Willcox Co., Inc.

On-Board Diagnostics
Cooling-related problems may set a
diagnostic trouble code on some
systems if temperatures seem out of
range.
use a scan tool to analyze the system
MIL lamp may be on
data will indicate engine temperature
even failure to bleed a system of air could
cause erratic temperature sensing
© Goodheart-Willcox Co., Inc.

Cooling System Functions
often monitored by the
OBD II system:
Coolant Temperature
Engine oil Temperature
Belt Tension
Other related functions

© Goodheart-Willcox Co., Inc.

Visual Inspection of
Cooling System
Perform a visual inspection for:
coolant leaks
loose or missing fan belts
low coolant level
water pump noises
plugged radiator fins
coolant in the oil (oil looks milky)
combustion leakage into coolant

© Goodheart-Willcox Co., Inc.

Common Problems

© Goodheart-Willcox Co., Inc.

Coolant leaks
Overheating
Overcooling

© Goodheart-Willcox Co., Inc.

Coolant Leaks
External leaks
most common
show up as wet, discolored areas on parts

Internal leaks
caused by cracked block, head or blown
head gasket

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A blown head gasket
can allow combustion
gases to enter the
coolant, a combustion
leak test will verify this
type of problem

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
Mineral deposits in
water jackets can
prevent proper heat
transfer

© Goodheart-Willcox Co., Inc.

Cooling System
Problems
A cracked part or
blown gasket can
allow coolant to leak
into the engine oil and
cause a milky white
substance to form in
the valve covers

© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc.

Pressure Testing a
Radiator Cap

© Goodheart-Willcox Co., Inc.

Inspecting the
Radiator and
Pressure Cap
 Inspect radiator fins for debris and rot
 Make sure the shroud is in place
 Perform pressure cap test
TO AVOID SERIOUS BURNS, NEVER REMOVE A
RADIATOR CAP WHEN ENGINE IS HOT!
 measures cap opening pressure
 checks sealing washer condition

© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Tester

one of the most commonly used and important cooling system testing devices
© Goodheart-Willcox Co., Inc.

Cooling System
Pressure Test
Low air pressure is forced into the system
causes coolant to pour or drip from any leak

Install pressure tester on filler neck
Pump the tester to pressurize system
Maximum 14 psi, (or cap rating) to avoid
serious damage to cooling system

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
 Should be performed when indications of a
blown head gasket, cracked head, or cracked
block are suspected.
 Checks for the presence of combustion gases
in the coolant
 Place combustion leak tester on filler neck
 Start engine and squeeze tester bulb, pulling air
through test fluid
 If combustion gases are present in the radiator,
fluid changes color (usually from blue to yellow)
© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Combustion leakage
can make
the engine overheat

© Goodheart-Willcox Co., Inc.

Combustion Leak Test
Leak testing with an exhaust gas
analyzer. HC reading indicates leakage

© Goodheart-Willcox Co., Inc.

Radiator Removal
Place a catch pan under the cool
radiator
Open the petcock to drain system
Disconnect hoses and oil cooler lines
Disconnect wires going to sensors and
fan motors
Remove any brackets and radiator
© Goodheart-Willcox Co., Inc.

Radiator Removal

© Goodheart-Willcox Co., Inc.

Radiator Repair
Most repairs are done by a radiator
shop
Radiator shops disassemble, clean,
repair, reassemble and test radiators
When installing radiator, make sure the
rubber mounts are in place

© Goodheart-Willcox Co., Inc.

Causes of Overheating
Low coolant level
Rust or scale accumulation in coolant
Stuck thermostat
Retarded ignition
Loose fan belt
Bad water pump or collapsed lower hose
Missing fan shroud or fan problems
Ice in the coolant
© Goodheart-Willcox Co., Inc.

Causes of
Overcooling
Stuck thermostat (open)
Locked fan clutch
Shorted fan switch

Symptoms of
Overcooling
Heater does not get hot
Temperature gage remains cold
Poor fuel economy
© Goodheart-Willcox Co., Inc.

A bad pump may leak, fail to circulate
coolant, or produce a grinding sound
Causes:
rust in the cooling system
lack of coolant
overtightened belts

© Goodheart-Willcox Co., Inc.

Visual Inspection

Pump shaft should not wiggle or leak
© Goodheart-Willcox Co., Inc.

Visual Inspection

Watch for leakage from bleed holes
© Goodheart-Willcox Co., Inc.

Removing a Water
Pump
Unbolt brackets and components
air-conditioning compressor
power steering pump
alternator

Remove pump
Scrape off old gasket or sealer material
Do not gouge the sealing surfaces
© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
Fit pump onto the engine
Start all bolts by hand
Torque all fasteners to specifications
Use sealer where specified
Install the other components

© Goodheart-Willcox Co., Inc.

Installing a Water
Pump
A. Gasket held in place by sealer
B. Sealer only

© Goodheart-Willcox Co., Inc.

Water Pump

This pump uses an O-ring seal
instead of sealer or gasket
© Goodheart-Willcox Co., Inc.

Installation
Tightening water
pump bolts

© Goodheart-Willcox Co., Inc.

Water Pump
Components

© Goodheart-Willcox Co., Inc.

A stuck thermostat can cause engine
overheating or overcooling
Stuck open–overcooling
loss of efficiency, power, mileage
high emissions

Stuck closed–overheating
engine damage
© Goodheart-Willcox Co., Inc.

Thermostat Testing
Watch the coolant through the opening
in the radiator neck
Cold engine, coolant should not flow
Hot engine, coolant should begin to
circulate past the opening
Use a digital thermometer to monitor
the temperature of the thermostat
housing

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

© Goodheart-Willcox Co., Inc.

Thermostat
Replacement

© Goodheart-Willcox Co., Inc.

Thermostat and
Housing

Special O-ring seal should be replaced
anytime the thermostat is removed
© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
A bleed valve is sometimes provided
Cars with low hood lines require a
bleed screw to empty air pockets
Trapped air can cause overheating or
damage from hot spots (buildup of heat)

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System
Fill the system
Start and warm the engine
Crack open the bleed screw until all air
is purged from the system
Never remove a cooling system
bleed screw or any clamp on a hot,
pressurized system

© Goodheart-Willcox Co., Inc.

Bleeding the Cooling
System

© Goodheart-Willcox Co., Inc.

Hoses deteriorate and become soft and
mushy or hard and brittle

© Goodheart-Willcox Co., Inc.

Common
Hose
Problems

© Goodheart-Willcox Co., Inc.

Hose Replacement
A. Loosen clamp, twist and pull hose off
B. Clean fitting
C. Install new hose and clamp, check for
leaks

© Goodheart-Willcox Co., Inc.

A loose fan belt will slip and squeal
may cause overheating

Inspect the condition and tension
Use a belt tension gauge to adjust belts

© Goodheart-Willcox Co., Inc.

A faulty fan can cause overheating,
overcooling, vibration and water pump
damage
Check for bent blades, cracks or fluid
leakage

© Goodheart-Willcox Co., Inc.

Testing a Fan Clutch
Start the engine
When cold, fan should slip
When warm, clutch should engage
you should hear the rush of air

© Goodheart-Willcox Co., Inc.

Testing an Electric Fan

A. Check for power to the fan, engine hot
B. Switch open when cold, closed when hot
© Goodheart-Willcox Co., Inc.

Leaking freeze plugs cause coolant
loss and overheating
Occasional replacement may be
necessary because of corrosion

© Goodheart-Willcox Co., Inc.

Freeze Plug
Replacement
A. Drive drift through
plug, pry out
B. Clean and coat
hole with sealer,
install

© Goodheart-Willcox Co., Inc.

Coolant should be checked and changed
at regular intervals
Breaks down and becomes acidic
Rust preventative properties are lost

© Goodheart-Willcox Co., Inc.

Changing Coolant

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be even with correct
marking on reservoir

© Goodheart-Willcox Co., Inc.

Checking Coolant
Level
Coolant should be
1” below the top
of the tank

© Goodheart-Willcox Co., Inc.

Testing Coolant
Strength
Measures the concentration of
antifreeze compared to water
Determines freeze protection
Tools used:
cooling system hydrometer
refractometer

© Goodheart-Willcox Co., Inc.

Hydrometer
When filled, pointer will float to indicate
freeze protection

© Goodheart-Willcox Co., Inc.

Refractometer

© Goodheart-Willcox Co., Inc.

Cleans rust and scale from the system
May involve running a cleaning
chemical through the system
Methods:
fast flushing
reverse flushing
chemical flushing

© Goodheart-Willcox Co., Inc.

Fast Flushing

© Goodheart-Willcox Co., Inc.

Reverse
Flushing

© Goodheart-Willcox Co., Inc.

Chemical Flushing
Used when scale buildup is causing
overheating
Chemical cleaner is added to the
coolant
Engine is operated for a specific
amount of time
System is flushed with water

© Goodheart-Willcox Co., Inc.

Gauge problems may include the
gauge reading too hot, too cold, or
not moving at all

© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test
Disconnect wire from temperature
sending unit
Turn key on, ground wire
If gauge sweeps or light glows as wire
is grounded, sender may require
replacement
Check service manual before this test
© Goodheart-Willcox Co., Inc.

Gauge or Indicator
Light Test

© Goodheart-Willcox Co., Inc.

Gauge Tester
Used if the gauge is suspected of being
faulty or out of calibration
Special device with a variable resistor,
replaces the temperature sending unit
in the temperature gauge circuit
Set tester to a specified resistance
Gauge should read as specified
© Goodheart-Willcox Co., Inc.

© Goodheart-Willcox Co., Inc. (12 Topics) Cooling system diagnosis Cooling system problems Water pump service Thermostat service Cooling system hose service Radiator and pressure cap service © Goodheart-Willcox.

Transcript © Goodheart-Willcox Co., Inc. (12 Topics) Cooling system diagnosis Cooling system problems Water pump service Thermostat service Cooling system hose service Radiator and pressure cap service © Goodheart-Willcox.

Directory