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Timing Belt Failure Is Rare Occurrence


Question: A garage manager asked me recently when I had last replaced the timing belt on my 1980 Honda Accord. I told him I had never replaced it. He told me I should do it promptly to avoid repairs and that it should be done every 35,000 miles. My owner's manual does not mention it. What is the proper thing to do? -W. B.

Answer: Motorists are often hoodwinked into buying timing belts when they do not need them, simply because timing belts are not exposed for easy inspection and a timing belt failure can cause serious damage to an engine.

A timing belt is a reinforced rubber belt, often about a foot long, which transfers the engine motion to the camshaft to operate the cylinder valves. The belt runs on a pulley from the crankshaft to the camshaft.

Although timing belts are critical, it is not true that they should be regularly replaced unless explicitly recommended in the owner's manual. If the manual makes no mention of it, a regular inspection every 15,000 miles should indicate when the belt is wearing out.

To inspect a timing belt, a shroud or cover must be removed. Often, this can be expensive, leading to the advice that "You might just as well replace the belt while I'm at it." That's terrible advice, because the belt replacement can cost $200 and the inspection should cost no more than $25.

Many timing belts can go more than 100,000 miles without failing. The belt in your Honda is designated by the manufacturer as a "lifetime belt," meaning you certainly can expect to get more than 100,000 miles from it.

If the belt is found during inspection to be cracked, frayed or worn down, then you should consider replacing it. Having a mechanic experienced with your make of car is critical in such a case. You don't necessarily need a dealership mechanic, because many independent mechanics are familiar with specific makes and can provide adequate service.

But if you have a general mechanic who is not familiar with assessing the condition of Honda timing belts, then most likely he or she will err on the conservative side, and you can count on getting a new belt whether you need one or not.

Q: My 1980 Chrysler LeBaron stalls in wet weather, but after being driven for about 3 miles it runs fine. Nobody has a solution to my problem. Do you have any suggestions?--J. E. S.

A: Almost any competent mechanic should have identified the problem as most likely caused by humidity inside the distributor, a condition that has been affecting cars for decades.

Your Chrysler has an electronic ignition system that does not use points or a condenser, but it still has a rotor and distributor cap to send electrical current to the spark plugs.

A cracked or worn distributor cap can allow warm moist air inside the distributor. Then, after the car is shut off and the engine cools, the warm moist air cools and condensation forms inside the distributor cap. The moisture can short out the distributor and prevent spark plugs from receiving proper electrical charge.

The car may still start, but it will run roughly until after it has warmed up and the moisture has evaporated.

The problem is easy to remedy by replacing the cap. You might also consider replacing the ignition wires, which after 11 years can become badly worn and subject to the same intrusion of moisture as the distributor cap.

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