Going to look at a truck this weekend, guy said it's pressurizing the coolant system. I don't know anything about the detroits but just guessing it's a head gasket. Anyone been in these motors and can help? Thanks
Don't overlook air compressor, it can put air in coolant
Double check that there isn't diesel in the overflow tank. Blown injector orings can pump fuel into the cooling system causing them to overflow.
Ours blew an oil cooler. Ton of oil in the coolant but i dont know if that would pressurize a system like that......