Is it safe to remove the "heat shield"?

Dear Car Talk

Dear Car Talk | Jul 01, 1991

Dear Tom and Ray:

I hope you can advise this 61 year old widow with a car problem. I own a 1986 Ford Tempo. Last year, I had the whole exhaust system replaced. A few months later, I noticed a buzzing sound coming from under the car, and I took it back to the place where the exhaust system was installed. They said is was probably the "heat shield" coming loose, so they removed the lower part of this heat shield. The noise is gone, but I'm wondering if this was a dangerous remedy. Is there a danger of fire?

RAY: Good question, Jean. The thing they removed--the heat shield--is a thin metal covering that surrounds the catalytic converter, which gets very hot when the engine is running. The upper part of the shield keeps your passenger compartment from turning into a sauna, and the lower part keeps things under the car--like leaves and grass--from being ignited by the heat of the converter.

TOM: And 90% of all mechanics will do exactly what your mechanic did--they'll just rip off the piece that's rattling. But we think it's our moral obligation to tell you that removing any part of the heat shield is potentially dangerous.

RAY: Although it's quite rare, there is a danger of fire. In the city, it doesn't happen very often, but we do hear about an occasional car parked over grass or leaves that catches fire.

TOM: If you were my widowed mother, I'd want you to have the heat shield replaced or re-welded (which they could have done before they tore it off).

RAY: And that's really what you should do, Jean. In the mean time, just try not to park over any leaves or tall grass. Or if you do, at least make sure you're carrying your emergency supply of marshmallows.

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