I have a 7.3 1994 f350 IDI turbo that is getting coolant in the oil and oil in the coolant. My dad is a lisence master mechanic and he is stumped. The first problem someone should think is the oil cooler and that is what my dad thought also, but that's not the case. We had the cylinder pressure tested to see if that was our problem but it doesn't seem to be. We replaced the o rings on the Cooler twice now. After replacing them, we pressure tested the coolant system and it's loosing pressure and forcing water into the oil and into the pan. We have no clue what to do. Someone help us. We talked to many people and they said that 99% of the time, it's the oil cooler but it's not. They also said that in this engine, head gaskets are not a cause. Help please.

 

Sounds like good ol cylinder cavation. AKA the block is JUNK

 

Could be cavitation. Search for "block worm" on oilburners.net I think that's where the article is that defines it.

 

How fast would the pressure drop in the coolant system if it wa a cavitation?

 

Could it be the intake gasket?

 

None of the signs match what my truck I doing. I don't have white smoke coming from my exaust and there is no excess water in the tail pipe. Plus in a cavitation, fluids only travel one way across the cavity, not both.

 

Yeah, you are correct, cavitation wouldnt let oil into the coolant. I think ive heard of oil coolers failing... the cooler itself not just the o rings.

 

We had the oil cooler pressure tested and the mechanic said it was perfectly fine.

 

Head gaskets could do it, but I would put a new oil cooler on just because it is cheap and easy

 

It can't be the head gaskets on a 7.3. The two don't run next to each other for them to exchange

 

Does the truck use one of the side tanks on the radiator as an auxiliary oil cooler? I'm not familiar w/ the ford diesels, I have dealt with this issue on VW diesel cars.

 

It literally has a brand new radiator. Not even 100 mile on it