abcxyzzz

Hi, I have an 2004 A4 3.0L Avant Quattro. When I press the gas gently and a little harder, it makes this intermittent screeching whistling noise, like a metal on metal screech. I didn't notice any loss of power or anything when driving.

I parked in my driveway and opened the hood and had my wife press on the gas gently. The noise sounds like it's coming from the front of the engine or under the plastic cover that I circled in the picture. I took the cover off thinking that maybe the serpentine belt is rubbing on it or something, but the noise was still there, not sure exactly where it's coming from.

CLICK HERE FOR PICTURE

Anyone have any ideas? Thanks!

twentysevenlitres

Similar noise in both my Audi's was the auxiliary (thermo) fan.
They whistle/screech as the bearings wear.
Press 'Econ' on the climate control and see if it stops (this may not work if you don't have an engine driven primary fan).

If it revs with the engine, I'd start looking at idler pulleys, or auxiliary items like the alternator.

abcxyzzz

I tried the ECON button and the whistle was still there. It even does it when I'm coasting, so not just when I push the gas pedal. it's not constant, but maybe every 5 or 10 seconds... if it's the aux thermo fan, how much is that to fix?