Hi, first of all apologies if i`m going over old ground but although i did find other posts i did`nt find anything specific to my engine. When i gave a friend a jump start today i noticed a tapping noise coming from either the top or possibly front of the engine that i can only hear with the bonnet open. The car is a 1998 A4 Avant 1.8 petrol. Sounds like tappets to me although i`m not expert! Any ideas?