I am posting this for my cousin who has a 1990 4Runner/22re/5speed/4wd with a slight problem....he discovered oil in his cooling system only. There was the cream colored mix in the radiator and overflow bottle but none in the crankcase. The motor is a used motor that has around 80000ish miles that was put in a few months ago but that was bought at least 2 1/2 years ago. And who knows how long it sat in the yard it was bought from. Apparently it has a one year warranty from date of install. We shall see.

There was no white smoke from the tail pipe, no overheating and no oil in the crankcase. He said it was down about 3/4 qt of oil and also down coolant. I believe it would be part of the head gasket that went but I'm no expert. All brain storming from the yotatech crew is welcomed. I said I would post for him so I'm sure he'll chime in at one point. He cleaned out the radiator by flushing the rad with the petcock valve open with the hose. He drove it a little today and it's back to the coffee mix. Start posting your thoughts, guys. Thanks.

 

I can't see any way for oil to get into the coolant without coolant getting into the oil too. Check the driver's side timing chain guide. It wears down and then the chain eats through the timing cover into the water pump housing, and voila! Milkshake. VERY common problem.

 

Oil pressure when running 25-30 psi. Coolant pressure when running = 15psi.

Oil pressure when off = 0 psi. Coolant pressure when off = 15psi.

However, that's only on the outlet (pressure) section of the pump. On the "inlet" side it will be 0 or minimal.
So what gaskets separate oil from water on the return (suction) side of the pump?
The only one I can think of off hand is the timing cover gasket.

 

Thanks for the quick responses.

I really can't understand it either but I saw it with my own eyes just before I posted. I am aware of the long chain guide breaking and the chain starting to cut through the aluminum cover on that side with the water jacket right there. But the dipstick was clean - no coolant in crank case. ????

Yeah, I see what you are saying xtreme, but why wouldn't the coolant would be mixing with the oil also and creating a mess in the case? I'm on the end of working a double here. I am real tired so maybe I'm not seeing it. If you could expand on your thought, I'd appreciate it. Thanks.

Before I posted here, I was searching for some answers about why just the cooling system and not the crank case also. It is puzzling to say the least. I know the head's gonna have to taken off at least to see what's going on in there. Again, thanks to any one who posts here.

 

I would if I thought my thought process behind it was completely accurate. lol. All I know is at one point I had a pin hole leak in my lower radiator hose (return). With the vehicle running it didn't leak, but when I shut it off, that's when the stream of water would come out. Which is why I had said 0 to minimal pressure.

The timing cover gasket separates the oil pump from the water pump passages in the front of the engine. And it's the only gasket I can think of that separates the inlet side of the coolant piping from the oil system.

 

Did he put in any kind of stop leak in before milk shake happened?

 

No...he was going to but I told him not to. Thanks for asking dude. Other guys I know at Advance told him the same thing. That's a temp fix but it not only clogs the leak but everything else.

 

Maybe a compression test? I'm not sure though I take it that its not running hot?. Also just wondering if before your cousin purchased motor if PO maybe put stop leak in it.

 

A compression and/or leakdown test will at least reveal whether it's a BHG or not. It seems strange to me for a gasket separating oil and coolant to fail outside of the head gasket, although I suppose stranger things have surely happened.

 

Yeah, I told him we should do a compression test on it. Like I said, at least that's what he told me - that it's not running hot. But yea, with all that crap in the cooling system you would think that it probably would run hot. The engine was purchased by his brother, who bought it from an salvage yard in Syracuse, New York. He bought it at least 2 1/2 years ago and the motor sat while the vehicle was waiting for the transplant. For entertainment value here, the reason the motor popped was me and my cousin "Hubba" had a Yota pulloff during deer season. I had my 88 4Runner with studded snows on and didn't realize the issue with studs on the bare road surface. We weren't exactly sober at the time He pulled me up the hill until he lost traction, then I pulled him down. This happened a couple times until the

 

Yeah, I told him we should do a compression test on it. Like I said, at least that's what he told me - that it's not running hot. But yea, with all that crap in the cooling system you would think that it probably would run hot. The engine was purchased by his brother when he had it, who bought it from an salvage yard in Syracuse, New York. He bought it at least 2 1/2 years ago and the motor sat while the vehicle was waiting for the transplant. For entertainment value here, the reason the motor popped was me and my cousin "Hubba" had a Yota pulloff during deer season. I had my 88 4Runner with studded snows on and didn't realize the issue with studs on the bare road surface. We weren't exactly sober at the time He pulled me up the hill until he lost traction, then I pulled him back down. This happened a couple times until the front half moon gasket popped out and he lost a ton of oil. He might have won the pull off, but I was the real winner. I drive my 4Runner home...his had to be towed.

Thanks for the thought DirtDriver. Will have to do that as well - leak down test. There are always stranger things that have and will happen...for sure.

xtreme, you might be on to something. Have to look into that.

Thanks for posting guys.