Transcript Powerpoint

AURT202166A
AUR30405
CERTIFICATE
REPAIR COOLING
III IN AUTOMOTIVE
SYSTEMS MECHANICAL TECHNOLOGY
AURT202166A
Repair cooling
systems
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Types of cooling systems
All internal combustion vehicles have a cooling system.
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Why have a cooling system?
• Remove excess heat so the engine
temperature doesn’t go too high.
• Maintain a minimum engine
operating temperature.
• Give a rapid engine warm up.
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Heat Transfer
Heat can be transferred in three ways:
1.
Conduction- heat transfers through the
metal parts
2.
Convection- heat transfers through the
coolant
3.
Radiation- heat transfers from the
metal parts to the outside air.
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Cooling system operation
• Extremely high temperatures are
created inside the engine.
• The heat is transferred into the
coolant.
• The coolant is pumped through
the radiator core and fins.
• Air passing through the radiator
fins reduces the coolant
temperature.
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Cooling system construction
Temp sender
Expansion
bottle
Hose
Cylinder
Head gasket
Heater tap
Welsh
plug
Radiator cap
Cabin heater core
Heater hose
Fan
Automatic transmission cooler line
Drain plug
Fan belt
Hose
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Engine coolant safety
Coolant is a mixture of water and
chemicals and it is poisonous.
• Wear personal protective equipment.
• Store or recycle used coolant safely.
• Don’t pour down drains.
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Radiator cap safety
1.
2.
3.
4.
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Allow the engine to cool down.
Place a thick rag over the cap.
Turn the cap anti-clockwise – 1/4 of a turn.
Press down cap and remove.
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External leaks
Use a pressure tester to find external cooling
system leaks.
Always check operating instructions before use.
External coolant leaks
can be in:
• coolant hoses
• radiator
• welsh plugs
• radiator cap.
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Internal leaks
For an accurate diagnosis use a CO2 leak detector to
help identify internal cooling system faults.
Always consult CO2 leak detector operating
instructions before use.
Internal coolant leaks
can be in:
• cylinder head gasket
• cracked cylinder head
• cracked cylinder
Head gasket
block.
leaking coolant
© Commonwealth of Australia 2011
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Cooling system checklist
Complete the inspection
checklist to ensure:
• you identify all cooling system
faults
• you make accurate
recommendations and
quotes.
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Reverse Flushing
What is reverse flushing?
• Forcing water through the
cooling system in the opposite
direction to clean the cooling
system.
Water in
Why do we reverse flush?
• To remove rust and scale from the
cooling system
Water out
• To remove the old coolant to avoid
cross contamination.
© Commonwealth of Australia 2011
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Welsh plugs
• Designed to seal the casting holes.
• Made from mild steel or brass.
• Most vehicles use the cup welsh
plug.
• Can leak coolant if cooling system
is neglected.
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Water pump
Pumps the coolant through the
engine and radiator.
Repair or replace when:
• noisy
• leaking coolant
• causing engine to overheat.
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Thermostat
• A temperature sensitive
control valve.
• Ensures engine reaches
operating temperature
quickly.
• Controls the operating
temperature of the cooling
system.
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Thermostat testing
Test the thermostat to check:
• opening temperature
• correct operation.
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Cooling fans
Test for:
• Correct operation
• Noisy fan motor
• Damaged fan blades.
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Radiator and hoses
May need removing to:
• Repair radiator leaks or
blockages
• Replace the water pump
• Replace engine or
components
• Service cooling hoses.
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Radiator and hoses
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© Commonwealth of Australia 2011
ISBN: 978-1-876838-58-4
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AURT202166A Repair Cooling Systems