Well... I'm stuck up in Thompson Manitoba. The oil-in-coolant problem is back. This is the first real road trip since my head gasket job, so I really didn't know until now if the job was fixed. There was always a little oil in the coolant due to residual still in the system. But now that I've driven 5000 miles, it's clear the problem is still here.

I'm looking for more areas where the oil could be leaking in. I have changed the oil cooler twice, head gasket, heads, and checked the tranny cooler.

I bought an spare oil cooler assembly last year. I'm planning on replacing the oil cooler caps, because maybe my oil cooler was fine, but the caps might have had a crack in them.

Also, can the water pump have any connection to the oil supply? If i replace that, could the oil stop infiltrating the coolant? The leak is terribly slow, so I can't really tell if it's fixed until I drive A LOT. Maybe one quart leaks into the coolant every 2000 miles. Any ideas?

 

I'd say someone is going to be on the lookout for a block ... It's likely got a small pinhole in one of the cylinders.

You either need to pressure test the cylinders at BDC or cheat and do lots of glow plug pulling ... heat it up, shut it down, after it sets pull the glow plugs turn it over, no water, try again next time until you find it. It's there somewhere.

Been there done that, Finally pin pointed it exactly with penetrating fluid inside the water jacket setting on the stand with the heads off.

-Enjoy
fh : )_~

 

It could by well be the water pump. Last summer I thought I had an oil cooler leak as I had some oil in the coolant. Then it developed a water pump leak, I had no time to work on it, so I took it to my diesel mechanic. It was all due to the water pump. At least one of the mounting bolts goes into an oil gallery, and that's where my oil and coolant were commingling. The bolt had no thread sealer. After the new pump was installed, no more oil in the coolant!

 

The water pump also seals between the timing cover, it could leak there and go behind the timing cover into the crank case/oil pan, but i am not sure how oil could be sucked into the coolant. Did you have trouble getting the oil cooler back together? You absolutely should not have to press it together if you clean it right and use th right o-ring lube and o-rings. The last one i did i took with one hand and pushed on the floor and it slid right in. I am going to make a video on the one I'm getting to reseal showing you dont need a jack, or a press, or anything to get those together if done right otherwise you risk damaging the o-rings.

 

I was just writing about this until I noticed your post. I remember reading in a topic about this water pump bolt with the recommendation to seal it with RTV or something... Do you remember which bolt it was? The topic that I read pointed it out but don't remember which one it was (upper left facing the engine?) I don't recall and way too tired to look for it.

It seems to me that if the cooling system is holding pressure, which it should after the engine is shut off, then the coolant under pressure would also be pushed into the engine oil - since the coolant level in the system is above the pump. Was that also your experience?

By the way, as this seems to be a known issue then it should be noted in water pump installation instructions.

 

I believe it's the top two bolts that go up by the timing gear for the injection pump. It's only splash oiling though so it'd be hard to get oil into the coolant there, but defnitetely possible to get coolant into the oil.

 

What usually happens is that if you don't seal those bolts, you'll get a tiny bit of oil migrating down the threads and out around the bolt head. It *shouldn't* leak inside the pump, because the gasket goes around the bolt. And, not to mention the high pressure coolant vs low pressure oil.

 

Thanks for the info on the water pump. I would think if that bolt or pump was leaking though, wouldn't I see water in my oil? I'v only seen oil in my coolant.

 

Try testing the coolant for combustion gasses ... It's cheap easy and fairly effective except in cases where the pinhole is deep in the bore as I suspect yours is.

It didn't work on my 94, Pinhole is ~3 inches down, No water in oil, No over heating, just a oil film in the coolant that wouldn't go away.

-Enjoy
fh : )_~

 

some one is not thinking,, the oil system has three times the pressure of the cooling system.. rad cap is 12 lbs engine will see 60-70 lbs cold at the cooler, before the regulator backs it down to 35-55, oil in coolant is usually caused by cooler, even in OTR trucks same same. very unlikely to get significant oil in coolant from water pump, as no oil pressure channels near water pump.

 

there are 4 bolts that go into the timing gear area.
they are the only ones that are not around the perimeter of the water pump/jackets.

 

I changed the oil cooler twice. Even bought a new one from the dealer. When (if) I get home, I'll change the oil cooler a THIRD time, but this time I'll change the oil-cooler caps as well. Maybe they have a pin hole leak, but the cooler itself it fine.

But I'm very reluctant to believe that the oil cooler is the problem. Whenever the oil builds up in my coolant, it drains A LOT more from the passenger side of the engine, rather than the drivers side. If the oil cooler was leaking, I'd expect a lot more oil buildup when I drain that side. That's why I thought I had a HG issue on the passenger side, due to the buildup when I pull that side drain plug. Since the HG wasn't the problem, that leaves a potential leak from the water pump bolts leaking into the passenger side, or the block is ****ed on that side.

I'm ordering another water pump gasket, and I'll remove and reinstall the water pump correctly. The PO replaced it right before I bought this van, so I suspect he didn't seal the threads properly, and maybe the oil is leaking into the coolant from there. It's a slow leak (about 1 qt every 2000 miles), but that builds up fast when we are on a roadtrip and driving 700+ miles per day.

If the new water pump gasket, new thread sealer on the water pump bolts, and the new oil cooler caps and gaskets do not fix this, then it's pretty safe to assume the block is f'ed. I considered doing a combustion test, but I doubt that would identify the problem. I'm not worried about combustion leaks, but rather the oil leak. And since it's not leaking coolant into my oil, I'd have to assume that the leak is VERY small so that it can resist the lower pressure of the coolant system, but not resist the higher pressure of the oil gallies.

Still in northern Manitoba. Hoping to keep syphoning the oil out of the coolant system enough to limp it back to the US.

 

Our stories sound identical ... Yup, even put on a brand new complete NOS cooler bought from that u-haul sale some years back.

I didn't mess with the water pump, it was original factory.

You'll make it home ... Have faith!

-Enjoy
fh : )_~

 

It pretty much has to be the cooler, that is the only place pressurized oil and coolant are near each other. Maybe the gaskets to the block have issues? A blown gasket often acts like a check valve-
Only other remote possibility I can think of is some sort of porosity in the block, but the less viscous coolant should be able to cross that as well.

 

You mentioned checking the transmission cooler - I assume by pressure testing the heat exchanger in the lower radiator tank. Were you considering that it might be transmission fluid? And are you now certain that it is OIL and not transmission fluid?

Aside from the beige oil sludge from blown head gaskets I've only seen transmission fluid leaking into coolant one time and that was so long ago (late 1960's) I don't remember what it looked like exactly. I don't want to imagine what it looked like because I am tempted to say it looked the same as oil from a head gasket leak but with red streaks in it - but I've seen transmission fluid mixed with water in a lot of other places outside of an engine too - pans left out in the rain, maybe mixed with oil too so I don't know what it would look like after leaking into coolant and being mixed up through the water pump. Anyone else know how to tell the difference and appearance?

In a youtube video I saw a 7.3L with bad cavitation leaks and the oil in the coolant overflow tank and under the radiator cap was coagulated, even crusty looking and BLACK as can be.

Is that what yours looks like? Probably in that truck it had not been driven long enough to mix it well with water.
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I am wondering if you can find the location of this leak - for example if it is a cavitation leak in a cylinder wall, by dropping the oil pan and then pressurizing the cooling system and keeping it under pressure for as long as it takes to detect a coolant drip. Maybe turning the engine over by hand a couple of times to change position of the pistons.

If the coolant level goes down and you don't see any coolant elsewhere then I would think that it's probably going into the oil cooler which you could then confirm. I don't know if that would work since I've never worked on an oil cooler.

You wrote that you changed the heads. Were the heads checked for cracks (magnifluxed) and pressure tested when you replaced head gaskets? That was one of my first thoughts.

I hope it's something you can economically fix.

If it was me I might try to find the heaviest oil possible for the trip back but I don't know of any options for diesel oil other than 15W40 or if you can thicken it with some straight 50 wt. (detergent if they make it) for gas engines OR if you can add some kind of sealant to the oil but probably wouldn't work for a cavitation leak due to high cavitation pressures at such a location.

Another thought, since the leak is small, it would be nice to have an effective coolant filter system with inexpensive cartridges that you could change along the way back. Might help a little bit.
That's all I can think of - actually I did think of something else if it is a cavitation leak a way to use a block sealer if you knew what cylinder had the cavitation hole - plug the injection line, remove an injector to eliminate compression and then lower the oil pressure by reducing the amount of oil in the engine and try the block seal but if it worked I don't think it would hold up for long and since it is a small leak probably just drive it back the way it is. --->
EDIT: Ooops I forgot, the cooling system will be coated with oil so that won't work