oil in coolant tank

Small amount of oil (engine) in my overflow tank. Pressure checked the engine oil cooler which is internal to the rad. It held 50 psi for 30 min. I am confused?? Where else can engine oil be getting into coolant. There is no coolant in the engine oil.

Any suggesstions.

Are you sure its engine oil and not tranny oil? Either way, I would still be looking at the rad, could have a pinhole leak, or weld cracks at the internal coolers, and since the oil pressure system runs higher for both engine oil and transmission oil when compared to the cooling system, oil would over come the pressure of the cooling system, and be leaking into it. I would be taking a better, more closer look at the rad only, pull it and get it pressure tested by itself.

Thanks, I stalled on that step trying to rig up fittings to test the tranny cooler (internal). I am using the same logic you mention about the pressure between the coolant and the lubrication curcuits. I think removing the rad will be my next step. Thank you for your assistance.

Rad has been replaced, seems to have taken care of the problem.

Glad to see you got it

hi there, i had the same problem, turns out my intake manifold gasket went on me, something to consider?

Rad has been replaced, seems to have taken care of the problem.'

You might want to do a coolant flush so that the oil doesn't break down/gel your coolant..Just a thought..(I'd do it)

Rad has been replaced, seems to have taken care of the problem.

I would change the oil, coolant and tranny fluid to get rid of any cross contamination.