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 cars.com on the World Wide Web.
?(C) 1999 by Tom and Ray Magliozzi and Doug Berman
Distributed by King Features Syndicate, Inc.