Can you think of any reason why a catalytic converter would catch fire while driving?

Dear Car Talk

Dear Car Talk | Sep 01, 1999

Dear Tom and Ray:

Can you think of any reason why a catalytic converter would catch fire while driving? -- Sharon

TOM: No.

RAY: I've certainly never seen it happen. And I've had cars come into the shop
with converters that were absolutely glowing red.

TOM: But it's possible for things AROUND the converter to catch fire. If your
engine was running rich or your timing was very retarded, a lot of the gasoline
could have been combusting inside the converter instead of the cylinders (those
are the most common explanations for red-hot converters).

RAY: So, if your converter was running hot and you ran over a garbage bag and it
got stuck underneath your car, the garbage bag could have caught fire. The same
could be true of a bunch of dried leaves or a flowering tulip tree that you ran
over 20 miles earlier and wedged between the converter and floorboards.

TOM: But I've never seen a converter itself burst into flames. So if you're
looking for an explanation for a fire that started under the car, look for
something the converter could have ignited rather than the converter itself.

RAY: And if the car still exists (you don't indicate in your letter), make sure
the fuel-air mixture and timing are correct and that the converter is operating
properly before you drive over your next tulip tree, Sharon.

Used cars can be a great bargain, and reliable, too! Find out why by ordering Tom
and Ray?-s pamphlet How to Buy a Great Used Car: Things Detroit and Tokyo Don?-t
Want You to Know. Send $3 and a stamped (55 cents), self-addressed, No. 10
envelope to Used Car, PO Box 6420, Riverton, NJ 08077-6420.
Got a question about cars? Write to Click and Clack in care of this newspaper, or
e-mail them by visiting the Car Talk section of on the World Wide Web.
?(C) 1999 by Tom and Ray Magliozzi and Doug Berman
Distributed by King Features Syndicate, Inc.

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