When I first bought my A4 Quattro 6 months ago it had a slight noise to it when I'd get up in speed. Last week it went from faint to loud. At low speeds it sounds fine but sounds like there is either a slight vibration in the mechanical fan or that the fan is spinning at a higher RPM than it is supposed to. I know that it is the mechanical fan because it is constant and does not stop with the electric fan. I've entertained the ideas of the fan blade having an imbalance or the bearing going bad but then someone brought to my attention that it may be the fan clutch. At high speeds on the highway (45+) it gets loud and is a howling but the weird thing is that when I'm in a turn to the right on the freeway the noise decreases almost to where it's gone, but when I'm bending to the left it gets louder. Hopefully someone can offer some advise before I have to go into trial and error mode and just buy a fan clutch to try. Any suggestions? Thanks in advance.

 

A bad wheel bearing will make a howling sound like yours. I don't think a bad bearing in the fan clutch would be as loud as what you're describing.

 

Yeah, I would guess wheel bearing as well. When the rear passenger side was going out, the noise would increase or decrease depending on the curve of the road. If it was a fan, I would think you would hear it when the engine is running and is parked.

 

I'll check all the hubs for above normal radiant heat after I drive it next time but it really doesn't sound like a wheel baring and I can't feel anything in the car that would make me think wheel bearing. Also when I'm on the highway/freeway at higher speed there is more air resistance on the fan, and so I believe that is why I get more noise at higher speeds, and so the noises increase and decrease while turning different directions could be because the shape of the fan has more or less resistance at different angles. Any other ideas?

 

Take the fan off and see if the noise is still there.

 

So I took the fan off and ran it and the noise is still there, so it's not the fan clutch. How would I isolate each wheel bearing and check them or do I have to take each one apart? I checked each hub for high temp. after driving and all were consistent warm but no hot. Would I be able to feel roughness if I jacked each wheel individually and span them? The noise sounds like I'm in a truck with some 44" mudding tires and driving through a tunnel, but that's not the case. Any other help? and thanks to all the replies so far.

 

Well, if the noise gets louder when you are going left, I would think that it's on the right side. As for which one, I don't really know how to isolate it.