I have this 1990 Volkswagen Vanagon Westfalia camper, a top-of-the-line model with 106,000 miles on the odometer. It is in showroom condition; only one owner.

I have this 1990 Volkswagen Vanagon Westfalia camper, a top-of-the-line model with 106,000 miles on the odometer. It is in showroom condition; only one owner.

The problem is the exhaust. It produces a very bad odor. I asked five to six auto mechanics in local repair shops and changed brands of gasoline four to five times. Nothing helped. I would appreciate it if you could help me solve this problem.

— J.P., Jacksonville

Hmmm. We backyard mechanics at SYA have been mulling this one over for several months now, J.P.

We even rolled up our collective sleeves and peeked under the hood of similar vehicles. Thanks to our astute mechanical minds, we quickly eliminated the dead-dog-in-the-engine-compartment theory.

However, if your bowser has been missing since late last year, J.P., you may want to poke around the engine area for bits of fur. That was an insensitive suggestion by a SYA staffer who will not be allowed to attend our annual backyard mechanic barbecue. No, sir, we do not tolerate such remarks.

Like you, we decided to call an expert mechanic, one we will call John D., because that's his name. Although he works largely on Subarus, he is a bright fellow who knows a lot about all things mechanical. In fact, one of our number — not he of the dog-in-the-engine theory — says there is nothing John doesn't know when it comes to engines.

While that may be stretching it a mite, John has a reputation for nailing down problems. But he cautioned it was difficult to make a diagnosis without having the mechanical patient at hand.

"And we don't know what it smells like," the mechanical detective observed. "If there is a rotten-egg smell coming from the exhaust, it might be a cat."

Et tu, John?

He quickly explained that he was referring to a catalytic converter, not a fur-lined tabby.

"It could very well be a bad catalytic converter," he continued. "But I would start by dumping some fuel injector cleaner in the tank and running it through. Do that a few times. It may help clean the exhaust."

Send questions to "Since You Asked," Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@mailtribune.com.