Well, If I had to guess, i suppose its possible that the no. 4 piston was damaged from, I dont know, maybe a blown head gasket, and valves hitting the piston.. I would also check the radiator to make sure its not leaking and also would pull the oil pan and check the bearings for wear, even know you might think its a good idea, dont worry about inspecting the pistons just becuase they all have 'eyebrows' in them from valves hitting them.. And while you at it, you might want to replace the heads because I am sure they are bad too,, the good news is..... it only cost 6500 bucks to get rid of the bubbles in the coolant.. I wonder how much toget rid of smoke rings?!?!!?
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