Have had problems with white smoke on these,if you look at the back of the head there is a stainless steel water cooled tube linked to your egr valve and had them leaking internally drawing coolant through your engine and exhaust,they are quite awkward to do due mainly to seized/rounded off nuts and bolts but if you manage to get it off blank one coolant pipe off,immerse it in a bucket of water and try pressurising the other pipe,you shouldn't see any air bubbles at all,it is not to say that is your fault but it is worth a look,good luck
cdc, March 2015
