Interference and Timing Christine Stewart

Objective  The objective is to impart a basic knowledge of interference engines and timing belts.

Parts of the Engine  Engine Block – the housing of the engine  Cylinder – the cylinder where the piston moves  Piston – a circular block that forces air and fuel in, compresses it, combusts it, then exhausts it (four-stroke engine)  Crankshaft – turns the connecting rod which pushes and pulls the piston

 Spark plug – creates a spark for combustion of air/fuel mixture  Valves – let fuel in (intake valve) and exhaust out (exhaust valve)  Camshaft – controls the valves (opens and closes them)  Timing Belt – a belt made of rubber that links the camshaft and crankshaft – the camshaft is geared to turn at half the rate of the crankshaft

Non-Interference vs. Interference Engine Source:

Interference Engines  The timing belt on any engine is hard to inspect – located under a cover on the front of the engine  Manufacturers will recommend a time interval when the belt should be replaced  On a free-running engine, if the timing belt breaks it won’t cause damage  On an interfering engine, if the timing belt breaks it causes severe damage – the whole engine may need to be replaced

 For cars with an interfering engine, if timing is incorrect, the pistons and valves collide, and the car will automatically stop working  If a belt is replaced it must be properly synchronized with the movements of the pistons and valves  Timing belt made of rubber with fiberglass or Kevlar fibers in it  Engine must be running well or else the rubber degrades, which can cause severe problems

Conclusion  There are both interfering and non- interfering engines  Interfering engines need to be brought in for check up to make sure the timing belt is still in good order  Timing is extremely important for a smooth-running car

References    m m m  me.htm me.htm me.htm