Audi a4 sport diesel auto 53 plate. All appears to be fine but last few days there has been a knocking/clicking noise from front end of engine. I've just had cam belt and water pump and tensioner done also oil and filter ... I have had a few people have a listen as the sound is very intermittent and can be when car is hot or cold. I went to audi this morning and it took him 10 mins of driving and only when he pulled up did it make the noise. He suggested the garage that did the belt change 2 days before I got the car should take a look first as they had the front end off ... So I have arranged to see them but any ideas would be a great help. I can make the noise come on by putting into reverse and without touching the accelerator let the car slowly creep back and there is the noise. As soon as I break it stops. It lasts 5 seconds 10 at most. It's random and not all the time. Can happen if I let the car move forward as in creep before I accelerate. Any suggestions ?