I bought a 7.3 idi just engine. When I went to buy it the guy said that it was in a 78 truck and it smoked a puff of black smoke when started but that was it. When I pulled the drain plug it drained out some water. The guy told me he was going to scrap it be cause I just finished explainin cavitation. Before I left with the engine he told me he left it out in the rain without the air cleaner. Could rain have gotten in threw the intake manifold and worked it's way down to the pan? I know that oil sits on water. Also what kind of damage can I expect from the water? The guy said it had been sitting out for a month. I don't think it's cavitation or a blown head gasket because years ago I pinched the o ring on my grandpas 95 powerstroke and the oil turned to a grey green sludge that looked like puke. We had to flush and replace orings and all good. The oil on the dipstick is normal and black, just a crazy idea that maybe water could get though thr intake and work it's way down to the bottom of the pan. I only know enough to get myself into trouble. I figured that at 100$ I couldn't loose just because all the parts. It's a v belt set up and I'm going to change it over to a serpentine.