Dear Tom and Ray:

I have a 1986 Volvo 740 GLE wagon. I had the exhaust system replaced from the catalytic converter two years ago, at a cost of $486.41. Last week, I took it in to have the timing belt changed, and when I picked it up, it sounded like a hot rod. When I complained, they showed me the rusted-out exhaust system and said it would need to be replaced again. What would cause it to rust through so fast? I drive the car almost every day and park it in the street, so it is exposed to the range of New England weather. Is getting a warranty worth it? Thanks so much! -- Laurie

RAY: Well, it's not unusual for aftermarket, replacement exhaust systems to last about two years. Especially in areas of the country where they're exposed to rain, snow and salt.

TOM: Particularly if the car makes a lot of short trips. On short drives, the exhaust system never heats up enough to vaporize the moisture that's produced by the engine. So the moisture just sits there and turns your exhaust system to rust.

RAY: There's really nothing the mechanic could have done while replacing your timing belt that could have damaged the exhaust system. Not unless he was rushing to the coffee truck, took a shortcut under your car and bonked his head on the thing while moving at full speed.

TOM: A warranty is fine. But understand that most warranties cover just the muffler (or in the case of some cars, like yours, the mufflers). So, the next time your exhaust system fails, if you're even lucky enough to (A) still have the car, (B) remember that you got a warranty, and (C) remember where you put the paperwork, you'll still have to pay for the gaskets and connectors, as well as all of the labor.

RAY: Muffler warranties typically are more marketing devices than consumer-protection devices. But if they give it to you for free -- which most places do -- put it in your glove compartment, try to remember that you have it and hope that it saves you a few bucks off your exhaust bill in two years.