When To Change Timing Belt

I was told I need to replace the timing belt in my car but my question is can I see the timing belt to see if it needs to be replaced and when should I replace it?

Dan

Hi there Dan,

No you can not see the timing belt, it is located inside the engine and has a hard plastic cover protecting it, the cover is called….wait….the timing cover and is located at the front of the engine.  The belt is critical for the engine to run, without it the engine will not run.  We usually suggest to the customer to replace the timing belt every 80,000 miles or so or as your owners manual suggests.

The bad part about a timing belt, when it breaks you are left walking BUT it can also do serious internal engine damage. The valves inside the engine in the cylinder head can come into contact with the piston which will cause the valve to bend. Once the valve is bent the cylinder can not hold compression. The repair is to remove the cylinder head and replace any damaged valves, and it’s very expensive.

The type of engine that can have damage due to a broken timing belt is called an “interference engine”.

Here is a good video showing the problem

A common source of timing belt failure is leaking camshaft and crankshaft seals, that leak oil onto the rubber timing belt. The oil causes the belt to swell and break prematurely. Just like the timing belt, you can not see those seals without removing the timing cover. You can sometimes see a trail of engine oil dripping out of the bottom of the timing cover. If you see that I would replace the timing belt and the seals.

Many vehicles also power the water pump with the timing belt, and the pump too is behind the timing cover. If your vehicles does this, it is usually recommended that you replace the water pump when changing the timing belt, since its a labor intensive job to remove the timing cover.

When the timing belt breaks, the engine will spin over much faster than normal because there is no compression taking place inside the engine. It will sound funny because the engine is spinning faster than normal, and you can remove the oil filler cap and look inside with a flash light to prove that nothing inside the valve cover is moving up and down like it should be.

This is a picture of a timing belt, notice the “cog” teeth, unlike a smooth serpentine belt which is visible with your naked eye and drives the accessories like alternator and A/C compressor.

Click picture to enlarge

If your engine is driven by a metal chain, looks just like a bicycle chain, you do not need to replace it as maintenance and it usually lasts the life of the engine without issues.