CG92

Hi guys I just nearly finished my first overhaul, I got everything together and fired the truck up. The engine ran perfectly but about 5 minutes after running I checked the oil dipstick and noticed a coolant oil mix basically white and milky. I am having trouble figuring out the cause of this problem. I know it could possibly be a cracked block, head, or bad head gasket. I pulled the head and saw a little coolant in one of the cylinders but the head gasket looked good. PLEASE HELP I AM STUCK! I have little money and that is why I overhauled myself. I purchased a used head from a friend do to the last head having bad rocker pads, camshaft and head bearing damage. Also the reason for the overhaul was seized engine, completely destroyed cylinder #1's rod bearing.

Thank you guys!!

spyderkrawler

ok your going to need to inspect the head gasket a little closer than just a look because the smallest crack could cause it to leak but from it being milky like your talking it could be worse than that. you could have a cracked block but don't worry yourself before double checking but if your gasket looks good its looking like a cracked block try putting the head back together and run another couple quarts of oil through it and see if you still getting coolant in there and make sure your head bolts are tightened within spec this could also cause a leak but before you put the new oil in it flush your bottom end with diesel fuel to make sure everything is out of there it wont hurt anything I do it to all my motors. if your still getting coolant in there after that its time for a new block hope this helps and wish you luck.

CG92

Is there any possibility of this problem from a bad timing cover gasket?

spyderkrawler

no because your timing chain cover only holds your oil in only. was it pure coolant that was on the piston? or a mixture of coolant and oil?

CG92

It was a mixture, the coolant added to the oil extremely fast after running it. How would I find out if it has a crack in the head or block?

spyderkrawler

if everything is right up top then its for sure your block so I would check your head for raw coolant on anything and put he head gasket in check your head bolts and make sure they are tight and within spec and crank the truck. go behind the truck and put your hand in front of the exhaust. if you smell coolant then its a bad head gasket or head if you don't smell it and your still getting an oil coolant mixture then you have a crack somewhere in the block that would be about the only way to know.

92yoterDD

Was your timing chain loose pre rebuild?if it was then it may have ate through the backside of the timing cover where the water jackets are. I experienced a similar problem on 2 of these. Pull the valve cover and look down behind the timing cover with a flashlight and mirror to inspect for gouging or leaks. A cooling system pressure tester would make this easier but only if the rest of the motor and cooling system is seales which it is not now I take it. At any rate , do what you have to in order to inspect that timing cover before you condemn the block. I have a new cover here awaitingy truck for the same issue.