Thanks in advance to all replys. I have a slight grinding noise in the accessory area. 1999 A4 1.8T 50,000m(no documented TB change). Noise not audible in vehicle. Noise very audible outside of car. Used a hose to try an pin point accessory bearings, unable. Noise is directly perportional to engine speed, no lag as if turbo bearing. Noise sounds to be coming from passenger side accessory area. Going to try and remove access belts to eliminate external bearings(assuming this can do zero harm for 1 minute, as water pump is internal drive). Initially noise would go away as vehilce warmed up, now constant. Does water pump have a weep hole if water has entered bearing? Any trouble shooting greating appreciated. Would like to get another 10,000 before TB change, but woun't risk it.

 

Its a grinding noise that increases in speed as the rpms increase?

It does it both in nuetral, and while driving?

hmmm.

If its more toward passenger side, that side is where the A/C compressor is, so thats a possibility.

Or, if it sounds like a dentist drill, thats a sign that the turbo may be on the way out.

 

Sounds like you have more technical skills than most here. It isn't the electric fan because the grinding noise changes with engine speed.

Have you turned the AC on and off to see if this makes a difference.

Have you tried listening from under the car rather from on top. Remove the plastic cover below and that will give you better access.

The other possibility is that it isn't a grinding noise but an exhaust leak. Check the flex hose connector on the exhaust, as these wear oout.

 

Will check under car, flex hose and A/C compressor today. Is there any way to tell if its the TB, TB tensioner, or water pump? Thanks for additional trouble shooting. Found power steering low, will get pen 11 monday, but thats not the noise maker.

 

serpentine belt tensioner bearing is a good place to start when it goes you loose the power steering/alternator because it drives the lot