Front end noise
 

I have 2000 A4 2.8l 5 speed m/t with 165,000. The other day I went through the car wash and after I came out I noticed a noise coming from the front end only when I accelerated. As soon as I let off the gas it go quiet. It was one of those car washes that pull your car through, but I had been through it plenty of times before this with no problems. The noise sounds like it coming from the front drivers side but as with any noise it is hard to tell. It is kind of a low grinding, scraping noise, with a slight vibration. It only seems to be in gears 1-3. Around 2-3k RPM although it will do it at higher RPM it doesn't seem as noticeable. It is not affected by turning so that leads me to believe it is not the CV shafts but I could be wrong? On the highway in 4th and 5th it doesn't not seem to make the noise. I had it up on a lift for a few minutes and could not find anything visibly wrong anywhere, front or back. I checked the rear diff fluid it was at the correct level a little dirty but not bad. I didn't check the transaxle fluid though due to time but that is my next stop. I would think if it was trans fluid it would be in all gears all the time though. I could be wrong. Someone had put used Cv axles on the front end before I bought it, but since it is unaffected by turning and it's not a "clicking" noise I was kind of steered away form that. Any ideas to point me in the right direction? My next step after checking the trans fluid is to get it on a lift again and run it and see if it doesn't make the noise. Any help is greatly appreciated, Thanks!

Wheel bearing? They make a grinding noise when they're on the way out. But I think they make the noise as long as you're moving regardless of if you're accelerating or decelerating.

I am with jeckel on this one. Sounds like a wheel bearing. Jack car up, to get specific wheel off the ground, and place hands at 12 o'clock and 6 o'clock position. Rock it back and forth. If you get any movement, you sir have a failing wheel bearing. Check to make sure your brake calipers aren't sticking slightly to the rotor. Could be something stupid like that.

could be a wheel bearing, but not necessarily. OP stated the noise doesnt change while turning. a faulty wheel bearing noise is load-dependent so if you are hearing the wheel bearing, it will typically change in tone/volume when you turn left/right. Not ruling it out, as the noise OP described is usually indicative of a wheel bearing, but the noise "should" change when turning.

I would look at the CV's again, check the boots carefully for rips or tears to make sure theres still grease in the joints. if you can get a second person to help you out, have them rotate and wiggle the wheel and other components up front while you hold your hands on the joints. feel for any slop/play in the CV's.

But like MrSnickelsnizer said, it can always be something stupid and more often than not it is so try not to over-analyze the problem.