I bought a golf 2.0 diesel a week ago and have just started to notice that when I shift from 4th to 5th gear there is a noise like metal on metal just a very quick buzz sound. It only happens when I am releasing my foot off the clutch. Only going from 4th to 5th. all other gears changes are fine and the car drives fine in every gear. Can anyone tell me what this problem is, and also what I will need to do in order to remedy the problem. Thank you.