May 1991

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Dear Tom and Ray:
I really enjoy your column! I own a 1985 Nissan Maxima with a curious problem. Whenever I turn on the defroster and put the air selector on "Recirculate," it's fine. But when I select "Fresh Air," I smell exhaust gas. This also occurs with the air conditioner. What could it be?
Aaron

RAY: You may have two problems, Aaron. First, and more importantly, you have an exhaust leak. Somewhere under the hood--possibly at the exhaust manifold--exhaust gas is leaking out. The first thing your mechanic has to do is find the leak and fix it.

TOM: Your second problem is that the exhaust is getting into your ventilation system. When you switch the selector to "Fresh Air," outside air is brought in through those vents on the hood right in front of the windshield.

RAY: And there's a gasket that's supposed to seal off the engine compartment from that fresh air intake. It's there to keep engine fumes--like exhaust leaks or burning oil--from getￂﾬting inside the car. It may be that your gasket isn't making a tight seal and needs to be replaced.

TOM: And this is something you should take care of right away, Aaron. Exhaust gas contains carbon monoxide, which, when you breathe it, makes you stupid, and then kills you. And the first sentence of your letter indicates that you may have already been affected!

Back to the May 1991 index

© 2008 by Tom and Ray Magliozzi and Doug Berman. Distributed by King Features Syndicate, Inc.

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Auto repairs can be costly! Save money by ordering Tom and Ray's pamphlet: "Ten Ways You May Be Ruining Your Car Without Even Knowing It!" To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.