White smoke from exhaust or blow by tube usually indicates that the head gasket is blown, or that the cylinder head or block is cracked(true for gas engines, assume the same for diesels). White smoke from the vent tube makes me think that you may have experienced a gasket failure or worse /forums/images/graemlins/blush.gif. Check the oil. I mean drain it into a clean drain pan. look at the oil. Is it white/gray and foamy looking, or discolored? Look at the oil fill plug. Is there a heavy coating of slimy gunk on it?If so, water (or antifreeze) has been mixed with the oil and made an emulsified mess of it (note that if run cold in the winter with a bad t-stat you may see gunk on the fill as water condenses in the engine). If not, decant the oil out of the drain pan and make sure that you don't have antifreeze at the bottom of the pan. If either condition presents itself, I'm guessing you have a leak between the cooling system and the crankcase. How much blow by is there? Is it a small amount or is it really pouring out? The vent tube (I assume the crankcase blow by tube) vents the crankcase to the atmosphere to dissipate pressure within the engine block. With no vent the combustion gasses that seep past the rings would pressurize the crankcase. blow by in a new engine is minimal, indicating that the rings are seated and the cylinders good. Excessive blow by indicates a worn engine in general or failure of a ring set, piston, gasket, casting,etc.
Guess the best bet is to start by checking the oil. If its not discolored, pressure test the cooling system and inspect the coolant. Pressure drop should be minimal if all the external parts (hoses, radiator) are not leaking. A film of oil on the surface of the antifreeze indicates that oil is being forced from the crankcase into the cooling system. Also good would be a compression test. If one cylinder is lower that the others by a significant amount, it is a pointer to problems. If you have kids, don't discount the possibilty of one of them "filling the oil up like daddy does". Believe me, I've seen things like that happen.
Take your time, walk through it and you should be able to diagnose your problem.
Good luck.
DaveL
