Pontiac Repair: Odd noise with my Pontiac Grand Prix, pontiac grand prix, michael donaldson


Question
Hi Scott,

I too am an Allexperts volunteer (Travel: Alaska & Niagara Falls), but now I need a little help from another volunteer.  

It involves a perplexing noise coming from the front end of my '91 Pontiac Grand Prix.  I've taken it to two dependable service departments already, and even the lead mechanics or specialist cannot figure out where the noise is coming from nor what could be causing it.  It's driving me batty personally...especially since it just started up about 2 weeks ago.

The noise sounds like a light-sounding buzzing (or what a tiny propeller would sound like if there was one attached to my vehicle).  It's coming from the front end somewhere, and the pitch goes up as I speed up and just the opposite as I slow down.  I'm far from any auto expert (I work on aircraft), but I've tried everything I can thing of like: weaving my car back-n-forth slightly seeing if it could be a wheel bearing going bad, and putting it in neutral seeing if it's the transaxle, or shutting off the engine while it drifts, but the sound is there no matter what!  It even has about 3-4 mechanics puzzled after they spent an average of 4-5 hours with it on two separate days.

So would YOU or any of your partners have a clue on what it might be?  Could you give me some more hints on other methods I can try to isolate the noise and pinpoint it.  By the way: the mechanics all checked over my tires, brakes, transmission, and axle area on the ground and on the hoist and told me everything is fine.   ?   Any help you can provide me will be greatly appreciated Scott.  Thanks!

 Michael Donaldson  

Answer
It's one thing to have a sound described to you than to actually hear it yourself so I'm afraid all I can do is offer suggestions as to what your problem may be. If your car is working fine mechanically then that eliminates a lot of possibilities. It may have something to do with your charging system, perhaps a bad belt or a whining alternator. It may also be something as silly as something being loose inside your engine compartment and as you go faster and slower it is being buffeted by the wind. But if your car is still making that noise even at a standstill then of course that wouldn't be the cause. If the noise only occurs at speed then I would definitly lean towards your steering and drivetrain system. A friend of mine had an odd noise occuring with his car and he tracked it down to low transmission fluid. Maybe you could double check that to be sure it's ok. Keep me posted on how this is going for you and in the meantime I'll ask around and see what else I can find out to help you. Good luck!