I have been searching for the right answere to this question forever, my 00 Audi Avant A6 2.7 engine could sound a few diffrent ways LIKE A DEISLE, SOME TYPE OF METAL CIRCULATION SUCH AS A CHAIN, Ive seen on line it could be due to a mechanical issue in the timeing area? now i know im not the only person to try and figure this out but i would greatly, GREATLY appreciate any direction that you could point me in. Thank you so very much