Pretz

'01 4.2 A6 58,000 mi. sometimes belches black smoke at start up. also seems to have excesive valve train noise during idle. anyone had anything like this?

ryoung

Black smoke is almost always an indication of an air:fuel mixture that's too rich (blue smoke is burning oil). The first step needs to be pulling any error codes with Vag-Com. The problem could be something as simple as worn spark plugs.

Is the valve train noise only at start-up or always? Where are you located (cold climate)? And what motor oil weight are you using? The 4.2 motor uses a (motor oil) hydraulic tensioner for the chain between the intake and exhaust cams. When the motor is first started, it's normal for that chain to rattle until oil pressure comes up and the tensioner is functioning properly. In extremely cold weather, a 15w-40 oil would probably be noisier at start-up than a 0w-40.

Kgnast-Nemo4.2

and it doesn't need to be low enough to set off the car's oil alert. Check the dipstick yourself.

Black smoke at start up??? Clueless.