'95 F3, Coolant in oil, NO oil in coolant
 

I've tried almost everything, and it hasn't worked so far so any suggestions are welcome.
The oil is very milky and clearly mixing with coolant.

I replaced the head gasket with an OEM replacement and flushed the oil 2 times with no change. I did everything according to the manual, using a torque wrench, and ensuring the mating surfaces were clean.

I did a full "rebuild" of the oil cooler, which included all new orings and even the little metal collars. I ran the bike, then parked it for a few weeks; when I came back, I drained the oil cold, and got a small stream of coolant before milky oil started draining. Flushed the oil 3 times, allowing the bike to warm up thoroughly and giving it some revs to cycle the oil, and it still comes out as a very light brown that's far too thin.

The weep hole on my water pump indicating a bad seal is completely bone dry. I removed the pump and it looks fine. I cannot find a new replacement, but there are some used ones on eBay. I'm hesitant to buy them because who's to say the same problem doesn't affect those?

The bike runs great aside from some mild rattling that I'm confident is just the CCT. The exhaust doesn't blow smoke. There are no unusual leaks anywhere. I have not replaced the oil filter because I didn't want to waste a new one while flushing the oil. I doubt that the small amount of contaminated oil in there could contaminate 3.4 liters of fresh stuff 5 times over.

The coolant is very clean with no contamination visible. The rad cap DOES have a little "sludge" stuff on it, but it seems more like dirt/grime from the bike's age rather than oil. I drained the coolant tonight to remove the water pump, and it looked very clear and clean.

I fear the worst, that the head is cracked or warped, seeping coolant into the oil, but I don't understand how it wouldn't go both ways even a little bit. I understand the concept of one pressure being higher than the other, but at low temperatures, wouldn't oil run at a higher pressure than the coolant, pushing oil into the coolant instead? I guess my next course of action is to buy another water pump, and getting another used one is a gamble. If anyone knows any better solution or where to get a new pump, please let me know.

When you had the head off, did you have it checked for cracks and the surfaces checked for warping?

There are only a few ports that the oil has pressure through the head. The rest of the head has oil just there and return ports are just use gravity to get back to the sump.

I didn't check, no; I'm considering removing the head again and inspecting everything, but I'm not sure how to detect warping.

I also just discovered upon further inspection that the cooling system does seem to have a thin film of very thick gunk lining some areas like hoses and the thermostat had a thin film as well. Not sure if this helps, but I guess it further proves that I'm screwed...

You need a very accurate straight edge and feeler gauge to check for warping and low spots. It also helps if you can "read" the old gasket and see the failure point, if there is one. When you took it apart, did you find the problem?

Water pumps can still mix without showing signs from the weephole. Can you pull it out without disconnecting the hoses and apply pressure to the cooling system and see if its leaking?

What's the history of this motor? Has is overheated or been wrecked?

Hadn't thought to pressurize the cooling system with the pump out, that's a great idea, but what would I need to go about that?

I don't think the bike ever overheated, and there's no signs of previous damage or wreck. It's been down before, but the fairings show only minor scraping; the previous owner said it happened in the grass and I believe it. I've had a hose come off and dump coolant while riding, but I noticed at a stoplight and caught it while it was still draining. I filled it up before starting again.

Once I find out how, I'll try testing the pump like you said before tearing down the head. Thanks

Cooling system pressure tester.

You may be able to borrow one from a local auto parts store that loans tools. They can get pricey to buy, but may be able to find one at a place like Harbor Freight, depending on where you are. If you were close to me, I'd let you use mine.

​​​​ Borrowed one today, here's what I found: removed the water pump from the engine, but left connected to the cooling system obviously to check shaft leak, filled with distilled water to avoid coolant clean up, drained oil and removed drain bolt, and pressurized system to around 19psi.

Once pressurized, every few seconds a few drops/little stream of water came out of the oil drain hole. The water pump didn't appear to leak.

I'm pulling the head tomorrow to inspect, and if I don't find and cracks, I'll try another head gasket. Will update

Update: fixed it. Absolutely the dumbest, smallest thing that cost me way too much time and money.

Turns out the two sealing plugs in the head had backed out so far that coolant was weeping right past the threads. Torqued them down and the system has been holding steady pressure for ten minutes.

Glad you got it squared away. It may seem dumb, but its better than replacing a bad head.

True that.

Do you know why those plugs even exist? As far as I can tell, they're just bolts sealing the water jacket from the valve cover for no apparent reason