Cummins 8.3L

This is neither antique, nor tractor, but I wanted to get exposure to as many opinions as possible. I have a CaseIH 1660 combine I have run for two small grain harvests and one corn harvest. It has over 5000 hours on it. It consumes a tiny amount of coolant. When parked it will occasionally leave a gob of gray sludge(typical of an anti freeze/oil emulsion) from the breather tube. Yet when I check and/or change the oil I get no sign of coolant. Is it possible I've got a crack or leaking soft plug in the head that leaks such a small amount up high only when running that it vaporizes? I've never seen anything like it. Any coolant leak into the crankcase I ever worked on was a sleeve, it wasn't tiny, and it didn't stop when the engine did. The oil cooler has obviously been worked on as there is no paint on it. I don't know if someone went after this problem, or what? Again, my experience is the much higher oil pressure in a leaking cooler will rapidly push into the cooling system, not the other way around. With the engine buried in its house up on top of this machine, I couldn't get it out of there in my shop if I wanted to. I am reluctant to start pulling the top of the engine apart blindly, only to find nothing and/or have to pull it anyhow.

The head gasket is out. With the newer headgaskets there is no real give and overtime they seep and then sealup when warm. This is a common problem with this engine in trucks not a big hassle.

I agree with this response given my experience.

Wouldn't hurt to run an oil test to see just how much AF is in your oil.

Hello Bob Bancroft,
The amount of leaking you are experiencing seems minimal. An easy thing you can do, is retorque the heads. A big leak offender are the head gaskets. Newer materials will cure most of the leaks from the old gaskets setup.
You can also do a coolant pressure test.
Look at the radiator cap, and pressurise the system with 10% more pressure then the pressure stamped on the cap. Any more you may couse coolant componet damage. Do the test with the engine (OVERNIGHT COLD). When the engine is warm the heat expansion has a tendency to seal the leaks, and you won't fid them.
Good Luck..............................Guido