Interference and Timing

Object: To distinguish between interference and non-interference engines, as well as emphasize the importance of timing belts.

What is a Timing Belt?

• Timing/Gilmer/Cam belt is part of an internal combustion engine. • Material: rubber • Purpose: control timing of engine’s valves • Some engines use gears or chains instead.

What does a timing belt do?

• Turns the camshaft at exactly 1/2 the speed of the crankshaft • Maintains a precise alignment.

• This means that the crankshaft will make two revolutions for every revolution of the camshaft.

• The camshaft causes valves to open and close in time with the pistons which move up and down in the cylinders.

• The valves must open and close in precise timing in order for the engine to work

Breaking and Replacing

• Must be replaced every 96,000 km to 168,000 km • Must be replaced if there is any damage like cracks, cuts or excessive wear • When it breaks, camshaft stops turning leaving some of the valves in the open position. The crankshaft continues to rotate by inertia. • The engine will stall, leaving you stranded.

Interference vs Non Interference

• Interference engine: pistons will strike the valves that are left open resulting in broken or bent valves, damaged pistons, and possibly, destroyed cylinder head. • The damage will be less extensive in a

non-interference engine http://en.wikipedia.org/wiki/Timing_belt