2005 Audi A8 • 10,700 miles

Two questions; Firstly all my mileage is around town, mainly low speeds. I have bought from a dealer a lovely condition Audi A8 TDI SE Quattro. Every so often I hear from the engine compartment when driving something like a compressor or other engine running, quite loud, with some vibrations for about 30 seconds then it stops. By the time I stop to open the bonnet it has stopped. This does not happen when left running stationary. Secondly sometimes when I stop the car ` vents ` deisel smoke grey from under ther front offside underneath of the car.I can see and hear the car settling as it has the 4 stage variable suspension system, what could be the noise and why does it vent diesel? This doesn not happen every journey?
March 24, 2013.

The noise is the air pump and it is working the way it should. Have the dealer replace it if it is that loud. Assume you have a warranty.

The smoke could be a exhaust leak. Have it checked to verify


Mar 24, 2013.