Recently purchased 1999 7.3L F-250 truck knowing that it would need some work. (Clear Smoke) Mixes the oil and coolant while running, coolant then becomes pressurized and overflows from the reservoir. Pulled off the oil cooler replaced gaskets and the two very busted inner O-rings. Thought that would fix the mixing issue. Started it and it mixed again just idling, dripping from the front of the oil cooler where it meets the block... Im going to tale off again in a week or two when I have the time to make sure that the front gasket was not damaged during installation and to double check the pipe for cracks. In the mean time does anyone know if something else could be causing this problem?

2nd issue, some diesel leaks when engine runs. I re-tightened the fuel filer assembly. No change. ???

 

Did you flush the system after you did the oil cooler change?
Where is diesel leaking from?

 

Yes, let the oil drain for a few hours to clean it out. Drained coolant and then rinsed it out to get all of it. Cant quite tell where the fuel leaks from you cant run the engine long enough to find out because of the leaking and mixing. The fuel drips down from the center of the engine so I have been checking seals and such in that region.

 

Injector cups

 

Is it possble the oil cooler has a ruture in it, anyway to pressure test it.

 

It could? Not sure how to test it

 

Has the truck heated recently, if so may have popped the sleeve orings?