Dear Tom and Ray:

I have a 1992 Suburban with approximately 50,000 miles on it. When we accelerate up hills, usually going between 60 and 65 mph, the front end of the vehicle shakes violently. We have taken the vehicle to our authorized dealer and they can't find anything wrong with it. Since it began shaking this way, we have changed the tires and have had the front end inspected and aligned twice. Nothing is wrong, according to the dealer. A friend of ours also had the same problem with his Suburban. He eventually traded his in for another make of car. Since the problem occurs haphazardly, we have had a hard time identifying it. Do you have any suggestions for us? -- Charles

Ray: I don't know exactly what the problem is, Charles, but I'm going to suggest it's not a front-end problem at all. Your dealer has checked the front end twice, and I'm going to take his word for it that the wheel bearings, steering components and structural elements are all fine. In which case, I think it's an engine problem.

Tom: If you had a severe high-speed miss -- something that caused the engine to skip and chatter at high speed -- you could certainly experience that as a shaking front end. After all, the engine is where? In the front end!

Ray: And if you simply reported a "front-end" problem to your dealer, he would interpret that as meaning the front suspension and steering components, which is what "front-end" means in mechanic-ese.

Tom: Rear end, on the other hand, is the rear suspension and differential, or, in my brother's case, where the mechanic's brains are found.

Ray: Anyway, if the problem never occurs when you're going DOWNhill at 60- 65 mph, that also points to the engine. And it's certainly conceivable that a miss would occur when the engine was working the hardest, which it would be pulling this tank up a hill at 60 mph.

Tom: Go back to your dealer and ask him to check for a "high speed miss under load." That should send him in the right direction. Good luck, Charles.

Changing your oil is the cheapest insurance you can buy for your car, but how often should you change it? Find out 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.

© 1996 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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