Dear Tom and Ray:

I have a 1989 Oldsmobile Regency Brougham. When driving in a very heavy rain storm, suddenly a loud roar/howling sound is heard. If I press down on the accelerator pedal the sound becomes louder, but when I release pressure completely, the noise lessens and finally stops. When I push down the pedal, the sound is heard again. Performance of the car does not seem to be affected. I talked to the service manager at the Oldsmobile dealer. He has never heard of this happening, and has no idea what it could be. I hope you can help.
Jack

RAY: Believe it or not, I think we can, Jack. We recently saw the same problem on a Buick.

TOM: It turns out that cold rain water was splashing up onto part of the hot exhaust system. When the cold water hit the hot metal, the metal shrank, and made a loud vibrating noise as it rubbed up against the underside of the car. After the exhaust system heated up again, the metal expanded and returned to its normal position, and the noise went away.

RAY: Ask your dealer to see if there's a Technical Service Bulletin on this problem (that's a notice from the manufacturer about a goof they've discovered after the car has been sold). If he can't find one, ask him to check with Buick, because I know they HAVE issued one. My guess is it's the same problem. Good luck, Jack.