Brown/Black radiator fluid

[The Mad Bishop]

Hi everyone, been a while since I posted, hope all are well. My 93, 7.3 has been running hot so I checked the radiator and found that the fluid is dark and thick. Manual said to check the oil cooler first since oil may be getting to the radiator. Can’t find it in the manual. Going to start in a few by draining and flushing the radiator. Any suggestions would be helpful. Thanks Mike

 

[OLDBULL8]

Yes, the oil cooler can leak oil into the cooling system. Cooling system pressure 13-16# Oil pressure 40-80#, and visa versa. With engine off and hot, cooling system pressure raises, check your oil for coolant also. After repairing the oil cooler, fill the coolant system with clear water and Dawn detergent, run engine til hot, then drain and flush, may take several times to get the oil out. Leave the cap off the degas so pressure don't rise when doing that.