Yesterday my 300 tdi DC started to make a tapping sound from the engine, on further investigation is sounds to be coming from the top somewhere. Its loud in the cab and you can also hear it in the exhaust.
A mate of mine said it could be the shim under the rocker and on top of the valve that has worn or come away.
I have a slight loss of power, but it starts fine cold or hot. Fuel consumption is up and it does not run as smooth as it did( for a diesel!!).
Any ideas boys??