Interference and Interference and TimingTiming

Christine StewartChristine Stewart

ObjectiveObjective

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

Parts of the EngineParts of the Engine

Engine Block – the housing of the engineEngine Block – the housing of the engine Cylinder – the cylinder where the piston Cylinder – the cylinder where the piston

movesmoves Piston – a circular block that forces air Piston – a circular block that forces air

and fuel in, compresses it, combusts it, and fuel in, compresses it, combusts it, then exhausts it (four-stroke engine)then exhausts it (four-stroke engine)

Crankshaft – turns the connecting rod Crankshaft – turns the connecting rod which pushes and pulls the pistonwhich pushes and pulls the piston

Spark plug – creates a spark for Spark plug – creates a spark for combustion of air/fuel mixturecombustion of air/fuel mixture

Valves – let fuel in (intake valve) and Valves – let fuel in (intake valve) and exhaust out (exhaust valve)exhaust out (exhaust valve)

Camshaft – controls the valves (opens Camshaft – controls the valves (opens and closes them)and closes them)

Timing Belt – a belt made of rubber that Timing Belt – a belt made of rubber that links the camshaft and crankshaft – the links the camshaft and crankshaft – the camshaft is geared to turn at half the rate camshaft is geared to turn at half the rate of the crankshaft of the crankshaft

Non-Interference vs. Non-Interference vs. Interference EngineInterference Engine

Source:http://www.carrsmith.com/timing%20belt.htm Source:http://www.carrsmith.com/timing%20belt.htm

Interference EnginesInterference Engines The timing belt on any engine is hard to inspect The timing belt on any engine is hard to inspect

– located under a cover on the front of the – located under a cover on the front of the engineengine

Manufacturers will recommend a time interval Manufacturers will recommend a time interval when the belt should be replacedwhen the belt should be replaced

On a free-running engine, if the timing belt On a free-running engine, if the timing belt breaks it won’t cause damagebreaks it won’t cause damage

On an interfering engine, if the timing belt On an interfering engine, if the timing belt breaks it causes severe damage – the whole breaks it causes severe damage – the whole engine may need to be replacedengine may need to be replaced

For cars with an interfering engine, if For cars with an interfering engine, if timing is incorrect, the pistons and valves timing is incorrect, the pistons and valves collide, and the car will automatically stop collide, and the car will automatically stop workingworking

If a belt is replaced it must be properly If a belt is replaced it must be properly synchronized with the movements of the synchronized with the movements of the pistons and valvespistons and valves

Timing belt made of rubber with Timing belt made of rubber with fiberglass or Kevlar fibers in itfiberglass or Kevlar fibers in it

Engine must be running well or else the Engine must be running well or else the rubber degrades, which can cause rubber degrades, which can cause severe problemssevere problems

ConclusionConclusion

There are both interfering and non-There are both interfering and non-interfering enginesinterfering engines

Interfering engines need to be brought in Interfering engines need to be brought in for check up to make sure the timing belt for check up to make sure the timing belt is still in good orderis still in good order

Timing is extremely important for a Timing is extremely important for a smooth-running carsmooth-running car

ReferencesReferences

http://auto.howstuffworks.com/engine.htmhttp://auto.howstuffworks.com/engine.htm http://en.wikipedia.org/wiki/Timing_belthttp://en.wikipedia.org/wiki/Timing_belt http://www.carrsmith.com/timing%20belt.hthttp://www.carrsmith.com/timing%20belt.ht

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www.familycar.com/CarCare/GatesFrame.htwww.familycar.com/CarCare/GatesFrame.htmm