i wish i could belive it was an easy fix. i have foamy oil and oil in the coolant i didnt know these had an oil cooler, where is it? could that cause the oil coolant mix of is the block doomed? i too thought it was, if not impossible, VERY difficult to cracka block. i was told by a local mechanic that if it had been run for very long with un treated coolant it could "cavitate" the cylinder walls

 

Oil cooler is behind the oil filter. If it fails, it can mix you fluids for you.

 

Alright, so I pulled my oil cooler. Nothing obviously broken. My question is, could a bad oil cooler cause HIGH pressure in the coolant system? As soon as it fired I had coolant coming out of the upper and lower hoses and the overflow bottle. The upper hose was noticeably hard with pressure. When I drained the coolant I pulled the lower rad hose and foamy oil/coolant flowed out.

 

The symptoms of high pressure are, as said before, the result of air in the block. If you just filled the completely empty radiator, without bleeding, it results in these symptoms. I think the pressure and oil are 2 different issues...Mark

 

You test the oil cooler by submerging the "radiator" part on the inside face down in a couple inches of water. Apply a small amount of compressed air to one hole while plugging the other with your thumb. If a bunch of bubbles come out from underneath, the cooler's kaput. If it's broken it will instantly mix oil and water in both systems.

When the head gasket blew, was the coolant system contaminated by oil at that point or is this new ? If so, you got all the oil out of there and flushed it repeatedly ?

How about the head gasket ? Is it a Cummins brand gasket or cheap aftermarket one ?

How bout the head ? Is it straight or warped ?

I would suspect any of those things before a cracked block. Rarely if ever do you hear about one of these early 5.9 blocks cracking, they are really overbuilt. But yours could be the exception here. And there are people on here a lot more knowledgeable than me...

 

when this originally happened i thought it was the head gasket because it is so rare to crack the block. the symptoms are exactly the same now as when it happened. it was running rough, then when i pulled over there was a huge puddle of coolant and oil on the ground. there was a mixture oil in the coolant and a little coolant in oil. i figured it was the head gasket and i put a brand new head on with a gasket from cummins and arp head studs among many other mods. when i went to start it it did the exact same thing, it almost blew the upper rad hose off and after i drained the coolant i pulled the lower hose of and a LOT of foamy oil came out. so with a NEW head and cummins gasket with arp studs is my block the only other answer? im talking a lot of pressure in the coolant.

 

Have you tested the oil cooler yet ?