Hi all,i've never explored the net in search of answers before but i am at my wits end. I have a 311 cdi which i use for work,i recently heared a noise and later discovered that the "cam carrier caps" had broken and therefore replaced the entire head. However the same knocking noise still persists and it gets quieter as the revs get higher (it virtually dissapears at 3000rpm). I've not driven the van since i've replaced the head as i dont want another one getting damaged but it has lost me work for the last three weeks and can't afford mercedes prices.I have noticed vapour spraying from an injector,could this cause a loud knocking and if so do they need any sort of calibration upon fitting? p.s-i used the same injectors from the previous engine.