Interference and non-interference timing belt or chain

In an interference engine, if a timing belt breaks while driving, there is a good chance that the engine might be severely damaged.

Interference and non-interference timing belt or chain. In an interference engine, if a timing belt breaks while driving, there is a good chance that the engine might be severely damaged. A non-interference engine will stall, if a timing belt breaks, but further damage might be limited.

The timing belt is actually a very finely tuned piece of equipment on your car. It must maintain complete alignment at the same it turn the crankshaft exactly two revolutions for every one revolution of the cam shaft.

Interference and non-interference

The exhaust valves and intakes are caused to close and open by the revolution of the cam shaft. The valve has to be able to close and open at the exact right moment when related to the movement of the pistons. Therefore, if that timing is off, everything else will be off kilter. This can also cause starting problems because the timing of all the individual components that cause the car to start will all be disrupted.

What happens if a timing belt breaks?

There are two types of engines:

Interference and non-interference timing belt or chain.

In an interference engine, if a timing belt breaks while driving, there is a good chance that the engine might be severely damaged. A non-interference engine will stall, if a timing belt breaks, but further damage might be limited. The difference is that in an interference engine,  valves that are fully open will be hit by the piston as it travels to its top position. In a non-interference engine, there is still some clearance between fully open valves and a piston in the top position. How to know if your engine is an interference engine? Here is the link to Timing Belt Replacement Interval Guide, courtesy of Gates corporation. In this guide, the interference engines are marked with the star sign.

Interference and non-interference timing belt or chain
Interference and non-interference timing belt or chain

Another reason to replace the old timing belt is that over time it stretches. As a result, the engine timing might become too retarded (delayed). Symptoms of a retarded engine timing include lack of power and slow pick-up. In some cars, a stretched timing belt can also produce a dull rattling noise coming from the timing belt area.

Usually the noise is noticeable at idle,

but disappears when the engine is revved. How much does the timing belt replacement cost? It depends on the engine. Timing belt replacement in a 4-cylinder engine may cost from $250 to $600, plus a little extra if you want to replace the water pump and other hardware. In a V6 or V8 engine, the timing belt replacement cost can run from $380 to $780.

Timing Belt
Timing Belt

Is it necessary to replace a water pump, as well as timing belt tensioner and other hardware along with the belt? It’s not necessary, however, it’s usually recommended, because a very little extra labor is involved in replacement of additional parts. Water pumps do wear over time, so it might make sense to replace the water pump along with the belt.

Timing Chain
Timing Chain

 

Do all cars have a timing belt? The answer is no, many modern cars have a timing chain instead. A timing chain is a maintenance-free unit and rarely need replacement.

When it comes to automotive maintenance schedules, they exist for good reason. Oil should be changed at certain times, spark plugs should be changed at certain times, and most of all, timing belts and chains should always be changes at certain times. Letting them go into “borrowed time” is risky business and could lead to auto repairs that outweigh the value of the vehicle itself, like a complete engine replacement for example. The risk highly depends on whether your engine has a belt or a chain and is an interference engine or not. If you don’t know if your timing components have ever been changed, then they may be due for one.

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About Danny Bender 104 Articles
DannysEnginePortal.com Is The Premier Automotive Engine Troubleshooting Resource Site. DannysEnginePortal.com Shares Information On Engine Troubleshooting, Engine Rebuilding, Engine Repair Tips, Tech Info, Basic Machining, Automotive Testing, In addition To Possible Solutions.

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