Hi all,

I have a problem with my Golf TDI 150, basically now & then when i start the car either hot or cold, i will get a knocking sound that last a few seconds.

When i'm doing around 50mph in 5th gear put my foot down the car will judder, also when the car is at 4k revs the knocking sound is heard although isn't that loud.

I took it into a garage last week, and because it never knocked, i was told to bring it back this week when the vw mechanic was in.

So today i ran it back, left it there, then get a phonecall to say they have removed the rocker cover and the camshaft has worn.

My question is, why does it only knock now & then (hasn't done it for over a week) if the camshaft has worn would it not knock all the time?