1993 940 Oil spewing out the coolant expansion tank

[98T5]

I know this is not normal. I didn't see any "chocolate milk" on the dipstick or under oil filler cap, but it's filled up my coolant tank. so my 2 questions are: what happend? and what do I need to do to fix it?

[98T5]

to note, Recenlty as far back as a month ago, I put some bar's leak seal in the coolant expansion tank to stop a heater core leak. not good. later found clumps of the stuff floating in the tank. fished them all out and kept going. end up re-routing the hoses for now. fix core later. but now this? could bar's leak messed up something?

the radiator isbrand new not even 2 months old. water pump is less than 2 weeks old.

cam seal oil leak since forever. could that have something to do with this?

again, no "chocolate milk" anywhere. even put a light inside the valve cover and the oil looks fine in there. but oil is IN the coolant tank.

[lummert]

ATF?

[precopster]

The way I dealt with this on my 960 was to shove a rag as many times as I could in the coolant reservoir and soak up the ATF. Then I let the rag dry so I could analyse the oil on it. The smell led me to believe it was ATF and that I had a breached ATF cooler.

I then bypassed the cooler with a B & M aftermarket cooler.

[98T5]

But it's OIL in the expansion tank not ATF fluid.

[precopster]

I would LIKE it to be ATF for your sake, however.......

Unless you have an engine oil cooler which uses coolant it will have to be a head gasket problem.

[98T5]

Ok, let me see if I understand,

IF it's not looking like "chocolate milk" and not under the valve cover or on the stick, it's ATF fluid?

can somebody verify this? and what about my leaking cam seals? would that dump oil into the coolant expansion tank somehow?

I need to know which way to proceed before I start buying parts. thanks

[precopster]

Is it OIL or ATF?? You seem certain then uncertain. They both look very similar when mixed with coolant, especially when ATF has darkened with use. The way I determined that it was ATF was that it would hardly stain the concrete when dry after I wiped it off my rag onto my driveway. Engine oil always leaves nasty stains.

The pressure in the crankase is around 20-25psi. The pressure in the cooling system is typically less like 15-18psi. If there is a pinhole in the head gasket the oil will naturally go into the cooling system from the oil system.

However be careful as ATF pressures vary depending on whether the car is idling or in use. Flow can go from the ATF system and vice-versa ruining transmissions.

[lummert]

Is it OIL or ATF?? You seem certain then uncertain. They both look very similar when mixed with coolant, especially when ATF has darkened with use. The way I determined that it was ATF was that it would hardly stain the concrete when dry after I wiped it off my rag onto my driveway. Engine oil always leaves nasty stains.

The pressure in the crankase is around 20-25psi. The pressure in the cooling system is typically less like 15-18psi. If there is a pinhole in the head gasket the oil will naturally go into the cooling system from the oil system.

However be careful as ATF pressures vary depending on whether the car is idling or in use. Flow can go from the ATF system and vice-versa ruining transmissions.

If this is a turbo car it should have an oil cooler with coolant hoses connected to it. The oil cooler should be where the oil filter is located. An internal oil cooler leak would cause oil in the coolant, but at the same time it could cause coolant in the oil.

[precopster]

Is the turbo 940 oil cooler a air to water cooler? I had a 740 turbo and don't recall water lines going to the oil filter area.