Oil in radiator no coolant in oil

[CUCVmike]

I have a fresh motor from about six months ago with 6.5 gaskets, and ARP studs and manga fluxed heads with only a few thousand miles (weekend toy) it's now got a tiny tach and a banks turbo. I go back roads other than 5-10 minutes on the interstate at 2,900 rpms max on my 4.56 gears and 37" hummer tires going no more than 75 mph. It's not over heated and it hasn't hot rodded with the turbo. I had the radiator tested prior to reinstalling everything. I have battery cut offs and when I went last weekend to turn the batteries back on the black coolant in the reserve tank caught my eye. There is no coolant in the motor oil and the oil looks good. The radiator shop said they couldn't test it any higher than 20 psi or so before. I wonder if the oil cooler could be leaking in the radiator? Any other thoughts or suggestions, I parked it in my barn so I could have a few days to calm down. I really hope I don't have to tear it down again.

 

[Drock]

Well I'm not really all that familiar with these diesel engines, but I imagine that your leak would be round the timing cover. Or perhaps the head gasket. Remember your cooling system is only 16psi and your oil pressure is around 70psi so the oil will overpower the water. Again I'm not real familiar with how these engines are laid out but your leak with be between a water passage and an oil passage. I'd start by doing a leak down test on the radiator (with the engine off and cold ). That may be the best way to find an elusive leak.

 

[rickf]

Determine if it is engine oil or transmission fluid. Both coolers are in the radiator. There are dyes you can put in the oil and see under UV light, just put in the engine oil and then put fresh water in and see if the dye shows up with new oil. With clean water you sometimes can see the red transmission fluid if your trans fluid is clean.

 

[CUCVmike]

I ended up taking the radiator cap off and then applying the throttle. No antifeeze spewed out and it was pretty and green like it came from the bottle. I then removed the expansion tank and cleaned it, refilled it, and reinstalled it. Driven it a couple of times now and its not changed color. Not sure what's happened but I'm going to keep an eye on it since everything has remained the same and was cleaned when installed the first time.

 

[eme411]

I had oil in the rad on my M-1031 when I got it , engine oil clean , oil cooler in the rad went boom, runs at higher pressure so that the way it goes,