I am the happy 2nd owner of a 1999 Audi A4 at a terrific price. Among the few items that need attention is a growling sound that occurs constantly and rhythmically from the driver's side rear wheel. Handling is not affected, and braking and/or turning don't change it either.

As speed increases, so does the occurrence of the sound, best described as 'whom whom whom' - apparently happening once per revolution. My first thought is that it's a wheel bearing, since the tire itself shows no missing tread or excessive radial belt wear; also I believe I'd feel it in the brakes if they were the cause. Of course I'm scheduled with the dealer to have it looked at next week, but forewarned is forearmed as they say, and I'd like a best guess on what the cause might be. Any other ideas? Thanks.

 

Definitely a wheel bearing. Both of my rear ones are shot and the left rear one makes the pulsating "whom whom whom" sound you describe. Blauparts has a special right now (assuming you're quattro) for two rear wheel bearings at $110 with free shipping. It also includes new hardware for the control arms and such that will need removed to change the bearing out. Here's the link: http://www.blauparts.com/proddetail....od=F7W1006-1-A

 

when you make a right turn, does the sound get louder? if not it's the brakes. the caliper is probably dragging. go out for a 5 minute drive then get out and touch the center of both rear wheels with bare hands. if the driver's side wheel is warmer, it's definitely the brakes.

 

Best guess it's the wheel bearing. The sound should change as you turn. I had the same with my right rear.