The engine makes a knocking every time I coast in while in gear (it's a 5 speed manual). Doesn't do this any other time. Also, there's a clicking sound every time I go in reverse. I don't know if these are related issues or not. Any advise would be greatly appreciated.
Knocking and clicking noises on 1999 Volkswagen Cabrio
Noises are so very hard to ascertain over the internet, best to have a good shop, most likely a transmission shop go on a test drive with you, since you say it happens only in 5th gear etc and clicks in reverse, could be a worn mount etc.
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This same thing was happening to my car and it recently broke down. It wouldnt let me change gears and a loud crash sound occurred and the wheels wouldn't rotate with the vehical. The mechanic said that bolts had broken off and fell into the transmission.