Timing Belt/Camshaft Drive Belt

This is the inspection of one of the car's most important belts — the notched rubber belt known as the timing belt, which is sometimes called a Gilmer belt. This belt allows the crankshaft to drive the camshaft, which in turn opens and closes the valves. Without this belt, the engine can't run.

During the inspection, your mechanic will look for signs of wear, such as cracks, shredding or excessive slack. He'll also look for signs of oil leaks from the adjacent seals, which can damage the belt and considerably shorten its life.

Should I do this service when it's recommended?

Yes.

Why do I have to do this?

Checking your timing belt for wear or looseness will let you know if the belt may likely break soon or if it may possibly jump a notch.

What happens if I don't do this?

If you don't periodically inspect your timing belt, it might break at an inopportune moment.

Many modern cars have interference engines, or motor wreckers, as we in the trade refer to them. If a timing belt breaks or jumps a notch in an interference engine, the valves may open at the wrong time and then be struck by the pistons. The result will be many hundreds of dollars in damage to your engine. Be sure to ask your service manager if your vehicle has an interference engine. If you don't have an interference engine, a broken timing belt will leave you stranded — which is inconvenient — but won't do any permanent damage.

Is there any maintenance required between intervals?

If you hear a slapping sound coming from your engine, it could be the result of a loose timing belt, which is hitting the plastic timing belt cover. To determine if your timing belt is loose, ask your mechanic to check its tension.

All cars have ways to adjust the timing belt tension. Some cars have self-adjusting mechanisms, while others need to be adjusted manually.

Can I Do This Myself?
It depends on where you rank on the Car Talk do-it-yourself scale:
There are two kinds of screwdrivers?
I've successfully hung pictures around the house.
I've changed my own oil.
I've fixed things on my car that involve removing more than five bolts.
I've built a working nuclear reactor out of wood.

Car Talk Tip: If you have an interference engine, don't try to squeeze every last mile out of your timing belt. Change it at the recommended interval. If your manufacturer recommends that you replace the timing belt at 60,000 miles, don't forget that this also means replacements at 120,000 miles, 180,000 miles and so on.

If you don't have an interference engine but want to go for the timing belt mileage record, by all means go for it. The worst that can happen is your timing belt will break, your car will stop running and you'll be stranded, but your engine will not be permanently damaged.

Posted on 3/31/05