Dear Tom and Ray:

I have a '92 Honda Civic LX sedan which developed a vibrating noise a few weeks ago. My mechanic said it was probably a loose heat shield, and I figured he would tighten a clamp or something. So imagine my surprise when I came back later to find he had removed the heat shield entirely. I asked him if it was safe, and he said it's perfectly safe. I'm not convinced, however. Why would the Honda engineers have put it there if it wasn't necessary? -- Robert

Ray: Well, if you took your car to 1,000 different mechanics, Robert, 999 would probably do exactly what this guy did, and charge you $25.

Tom: And the other guy -- the one who'd been sued because a customer's car caught fire -- would have installed a new heat shield and charged you over 100 bucks. And we'd have to endorse that guy's action, mostly because our lawyers insist upon it.

Ray: Most cars have several heat shields ... .some more important than others. The one most commonly removed by mechanics fits just below the catalytic converter. It's designed to keep a hot converter from igniting stuff underneath the car, like dead leaves and tall, dry grass you might park on top of.

Tom: So if you live in a city, and never park in a dry meadow, you can probably get by without that heat shield. But there are situations where something is wrong with the engine and too much fuel pours into the converter, causing it to overheat. And under those circumstances, the converter gets red hot and can ignite something and set the car on fire if no heat shield is present. And that's really why the engineers put it there.

Ray: Not that having your car catch fire is always a bad thing, Robert. My brother's car doesn't even have a catalytic converter, but he installed one hoping that he could get his car to spontaneously engulf itself!

Which is cheaper, buying or leasing? Should you keep a car forever or dump it after three years, before trouble starts? Find out in Tom and Ray's pamphlet "Should I Buy, Lease, or Steal My Next Car?" To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1998 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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