I have a strange noise coming from the front...It is like " tch tch" ...I can feel it through steering wheel... It takes only a second and only once and it only happen when I start engine and move forward (wheels are straight or left or right),never on reverse, it never happened if I stopped the car (engine on), clutch down or neutral and moved forward again.

So it only happen when engine is off and then again on... Any idea?

AUDI A4 B6 1.9TDI 96kW 2002 AWX engine, 85.000 miles