After a bit of searching i couldnt find any coherent info on what can cause Knocking in the 1.8TDCI
this only happens every now and then but on start up you can hear it knocking very clearly as did a passer by who threw a funny look . thing is as soon as i put it in gear its gone and wont come back untill the next journey, maybe not even then its been so intermittant that ive not paid any attention to it.
Any ideas what it could be? car was serviced in April by myself, did Air, Fuel and oil filters plus oil change, slightly overfilled. was knocking before this however.