I've done some searching and it looks like the term 'grinding' is a popular one when describing problems, but I think mine might be slightly different. This noise started out a few weeks after I bought my car (2001 A4 1.8t stock) and would only happen in the mornings when I depressed the clutch. It almost sounds like a fan rubbing up against something. Then it began happening when I turned at low speeds when the engine was still relatively cold. Now it sometimes happens when the engine is plenty warm and when I'm just going straight in 1st or 2nd gear. I don't think it's a CV boot since it happens when going straight. I've read from one moderator’s post that this could likely be a wheel bearing, but would this be the case since it happens when I go straight too?

 

My 2000 has a bad wheel bearing and it makes a "wub wub wub wub" sound as you drive, no matter straight, turning etc. Could sound like a fan rubbing on something i guess.

 

I had a 99 integra gsr that did the exact same thing, only when the clutch was engaging. It got stolen before I could figure out what it was. Could be a worn pilot bearing in tranny. I have no clue.

 

same car same problem. ive got a 2001 1.8t stock and its making the same noise? i have been told that on audis there are tons of small protective plates all over the car and if they get tapped just a little bit they will rub agianst somthing? this is the only possiblity that has made sense to me

 

Where does the noise sound like it is coming from? Does it only happen when the car is moving?
It sounds like either a wheel bearing, or tire noise if it is coming from a wheel well. If you rotate the tires and the noise stays in the same location then it is likely a bearing.

 

HA HA I told dubiousmusic that.

It is so true. You might check out the whole post to him, that was all of my ideas on it.

But the rubbing plates is seriously the most likely for little grinding noises that seem to have no apparent reason. The best way to pin down the location (other than the dealer who will fix it for 1/2 hour labor) is to have a couple of inteligent friends in the car with you and have them stick their heads out the windows and decide which portion of the car is grinding (you can tell why you need smarter friends) and then go to that side and spend a half hour or so finding little metal plates and pulling them back. There is one that rubs the rotor that is really common to get rubbing, there are two on the axles to protect axle to body, I am sure there are more. Anyway, you just kind of have to search around.

Most other problems will be more prevalent at high speeds and not go away, this one however is only noticable at low speeds because at high speeds rubbing will just be a hiss that could just as well be wind noise. My second recommend to dubious was rubbing brake pads (brand new brakes that were adjusted to tight), you might fall in this category too because used car dealers have to replace brakes with more than some percent wear.

 

dan908 you taught me everything i know