Hi. I have a '92 Explorer with the 4.0 V6 EFI engine (pushrod type). It has 280K miles on it. When I first start it up I get a lot of white smoke from the tailpipe and it runs rough. After a while the smoke gets to where it's not really noticeable and the engine runs smoother. Recently the radiator burst and lost all it's coolant. I started the engine and ran it briefly with the low coolant level and there was no white smoke and it ran smoothly. I could find no signs of water in the oil. I drained about a quart from the engine into a clean bottle and checked for condensation on the dipstick and fill cap. The oil looks normal and not foamy or frothy etc.
My question is if it has a blown head gasket, cracked head, or cracked block would there definately be water/coolant in the crankcase or could it have one of these conditions and NOT have oil in the crankcase? It seems to me that coolant is getting into the top of the cylinder and causing the white smoke and rough running. If I do a compression test should it read low on one or two cylinders and would this be conclusive, or with an engine this old would it be a waste of time and money? What else could cause coolant to get into the engine? Bad intake manifold gasket?
Thanks.
Jim