I brought 2.5 tdi A6 manual in December with a whining noise coming from the front of the car. It sounded like a wheel bearing noise so i thought would be an easy fix. I changed the nearside wheel bearing and the noise was still there. So i then changed the Offside bearing and the noise is still there. The car has just had the gearbox taken out of it and all bearings replaced thus elliminating this. Have no idea what it could now be. The whining starts at around 10mph and continues to get louder and higher in pitch the faster you get. The noise is there when its in or out of gear. No change or effect when braking. The only thing that makes it change is the velocity. Any ideas anyone ?

 

From your description and attempts at repairs, it sounds like you have good idea what you are doing. I am guessing you have eliminated the noise as a tire noise. ??? correct?
If you have not, inflate tires to about 10lbs or 12 lbs above recommended tire pressure. Does pitch change?
Put tires back to regular pressure. Does noise change on sharp turn at about 25mph to 30mph? If so, which direction? That would indicate weight being added or removed from bad bearing, axle, or hub/spindle.
I am guessing this model is fwd. Have you raised both front wheels and put in gear and drive wheels at 20mph? do you hear noise?
Do you feel a grinding or roughness if wheel is rotated by hand?
Are you sure noise is the front wheel and not a rear wheeel noise echo'ing?
Bob

 

Have changed the tyres recently and there was no change in noise and ive examined them and there are no signs of stepping or going out of shape. Sound doesnt alter if you turn left, right, up a gradient or down. It is front wheel drive. Havent raised wheels and run it so will try that when i get it back from gearboxman but having a dispute with him so not sure when. There is no roughness or grinding when you rotate the wheels. ???? Someone has mentioned that it could be the driveflange/hub being worn so all the pressure is on the outer race within the hub assembly thus causing the noise. Also had somene say it could be the drive shaft but theres no clicking noise at all. Will carry on with my quest when mechanic agrees on how much he deserves to be paid after hes mis-diagnosis.