A66 oil in the coolant

Haywire

New User
A66 wheel loader with 1983 401t started putting oil in the coolant, head was pulled and checked no issues found head gasket appeared fine, no oil cooler on the machine other than the one for the hydraulics. I am assuming a cracked block, from the topside with the head off everything looked good. No water in the oil just oil in the coolant. Any tests or things to look for before pulling the motor??
 
There should be an oil cooler for that engine, likely in the bottom of the radiator tank. This is the first place I'd look for trouble if the situation is as you describe.
 
The radiator is setup with oil cooler as you described but no lines are ran to it. I am guessing last owner swapped motor at some point and never hooked back up.
 
Are you SURE there is no water in the oil? Was there any mayonnaise on the underside of the valve cover?

Those engines are without a doubt the most likely Ford engine to pinhole, especially of that vintage. And, it always starts with mayonnaise under the rocker cover and oil filler cap.

If you are certain that there's no water in the oil, I'd flush the cooling system with Cascade dishwashing soap and run it some more, just to be certain you're not imagining things, or that someone accidentally (or otherwise) put oil in the radiator. It doesn't take much oil to make a nice sheen on top of the water level inside the radiator.
 
Hey Bern thank you for the reply's. I'm very confident with saying no water in the oil, bottom of oil cap and under valve cover is no milky residue just nice black oil and oil caps dry, I dropped some out of the bottom and its nice black oil. I did clean the radiator fairly well but I am sure there is some residue I missed but I wanted to see if it was fixed before pulling and having it cleaned at the radiator shop. When its running the water level rises in the radiator pushing some coolant out then a glob of oil comes to the top, I have been scooping that out then water level randomly drops for a bit 30seconds to 3 minutes, then it does it over again it ran for 35 minutes doing that at an idle with a few times I revved the motor some, oil pressure held steady at 65PSI motor revved it would go 75-80psi this motor has always had great oil pressure. After shut down I let it sit 20 minutes for all of the oil to drain back into pan to check level again after that time it was 2.5-3MM lower than when I started it. It sure seems like a lot of black sludge to pull from coolant with it only being that low. the sludge doesn't seem to be mixing with coolant but it looks like black cake batter.
 
If you have a genuine problem (and I'm not convinced yet that you do), then you must have a strange crack somewhere in the block that would be very rare indeed. I suppose it's possible that you could have a crack somewhere between an oil gallery and a water jacket, but again, that would be extremely rare for these blocks. Myself, I'd keep using it and watching it close to make sure I wasn't imagining things.

With regards to oil pressure, if it's a 1983 engine, then it should have a TW style, crank driven oil pump. Those pumps are notorious for oil pressure issues. If you ever have the pan off, inspect the oil pressure relief valve and bore carefully. If you don't, it's entirely possible that you might go from great oil pressure one day, to lousy the next, just because the relief valve is stuck open.
 

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