i've been working on an isuzu c240 diesel engine that smokes a whiteish blue, and runs like crap, we did a new pump and injectors and still the smoke, we compression tested and the compression was anywhere from 300 to 320, new fuel filter air filter and new fuel, the oil is WAY sludgy. do you think that there is a bad seal on one of the valves or am i missing something here. changing the timing doesn't seem to help either. any one have any idea's? all help apreciated.