How do we know when to change a timing belt (or chain) when we can't see into the enging to look at it?

Dear Car Talk

Dear Car Talk | Mar 01, 1997

Dear Tom and Ray:

We've been told that after so many miles, the "timing belt" or "timing chain" should be changed, or dire consequences will result. Since we can't see inside the engine, how do we know when to make this change? I have a 1992 Mercury Grand Marquis with 65,000 miles on it, and I feel like the sword of Damocles is hanging over my head. -- Joe

RAY: Isn't that interesting, Joe? Whenever my brother is nearby, I feel like the sword of Dumbocles is hanging over MY head!

TOM: Generally speaking, a timing belt should be changed every 60,000 miles. And some cars -- notably Hondas and Nissans and some Mazdas -- do experience catastrophic engine damage when their belts break. So owners of those cars in particular have to be sure to change their timing belts on time.

RAY: But you don't have to worry about that, Joe, because your Grand Marquis doesn't have a timing belt. It has a timing chain (by the way, if any of you readers aren't sure what you have, you can always try asking a repair person at the dealership).

TOM: And as a rule, you don't change a timing chain until it breaks. And it may never break. Unless you drive like a complete animal, it should last you well over 100,000 miles. Most of them last 150,000 or more. If and when it does break, it's a big job, and it'll cost you twice as much as it would to change a belt. But as I say, you may never have to worry about it.

RAY: And when a timing chain starts to go, it usually makes a loud "rapping" noise (by rapping, I mean like metal hitting metal, not like Snoop Doggy Dog). So you usually have some warning.

TOM: So feel free to relax, Joe. Rest assured, your time is much better spent worrying about what Alan Greenspan's going to do at the Federal Reserve than worrying about your timing chain.

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