My 2000 A6 2.7T makes a strange noise up front only on cold starts. Sounds like a pulley bearing or something rattling from the front of the engine plus the engine runs rough. It disappears after about 60 seconds and the engine runs smooth. Had new timing belt kit installed 4000 miles ago. Mechanic says it's not the timing but it may be the accessory belt tensioner going out. You would think that a worn bearing in the thing would not repeatedly heal itself in 60 seconds after each cold start.

I posted a video of it at

VID_00000004.mov - 4shared.com - online file sharing and storage - download

Anyone else had something similar? Thanks.

 

Only thing that I can think of making noise at cold start up is the secondary air injection pump. Normally a high pitched whine, but it could be that the bearing went out or something.