Hello all, I have an issue with water in the oil of my 951C 86J with 3304 engine. I wasn’t sure if I should have started a new thread or added to one of the others about this issue. I have searched forums and gotten some good ideas on diagnosing this, but now I am at a loss. Sorry for the long post, but this thing has me stumped and wanted to supply as much information as I could to the best of my memory in the order I did things.

• Changed oil, had a bit of a grey color to it, noted to self to keep an eye on engine oil for possible trouble.
• Drained coolant, no oil was present, but it was thinned down looking. Removed plug from block, last bit of coolant was a little dirty. New coolant added. I noticed the next day coolant was a little low and figured it was air pockets working their way out. Decided I would wait till I had run it a little bit and then re-check and top off.
• Machine sat for about a month with just some intermittent running while I removed both track frames and replaced recoil spring, track adjuster, removed broken track frame mounting bolts and rebuilt hydraulic cylinders….all went well.
• Ran the machine for about an hour to check and top off new transmission fluid change, top off hydraulic fluid and drove a few hundred yards to check that everything in the tracks were working properly.
• Few days later I checked the coolant level, was very low, could not see coolant level in radiator. I cracked the oil drain plug and yikes, out came almost 2 gallons of nice bright green coolant. I then drained the radiator and block to try and salvage what coolant I could. The coolant was clean with no oil in it.
• Drained the oil after most of the coolant came out, the oil was still “clean” and had not appeared to have mixed well with the coolant to get a grey or chocolate milk color.
• Dropped the oil pan sump (plate is still in place) and filled cooling system with water, no obvious leaks found. Installed pressure tester on the filler neck were the pressure relief cap goes, noticed the large filler neck was leaking air even after making sure it was tight, the rubber gasket was not in good shape so I don’t think the machine was ever building up pressure in the coolant system. This would probably explain why when I went and looked at the machine before buying and I removed the cap to check for air bubbles in the radiator there was no pressure even though the machine was well warmed up. I could not ever get the hand pump pressure tester to keep a good seal so I removed it, installed the radiator pressure relief cap and piped in compressed air to one of the spare ports on the water pump I used a local regulator, shut-off valve and 0-15 psi gauge . Still no signs of a leak with 15 psi. Removed pressure and gave up for the day.
• Was looking like this may be a really slow leak that may be hard to find and since there were still green coolant drops showing up the every now and then I decided to drain the water and mixed up some blue dye in fresh water and added back to the system to try and distinguish what was residual and what may actually be the leak. Pressurized the system to 14 psi and crawled back underneath…nothing, checked every few hours…still nothing coming out of oil pan area. Removed the injectors and turned motor over with the starter, nothing blew out of the injector holes. Removed the cover on the back of the water pump, nothing. Removed valve cover…nothing. Removed oil filter...nothing. I had used the shut off valve and disconnected supply air to see if it would hold pressure, held fine for several hours before I called it quits for the day. It has been holding pressure for 3 days now, varying up and down a couple psi depending on the ambient temperature.

I did notice right before I discovered this problem that there was some black nasty liquid that had dripped out of the weep hole in the muffler and onto the manifold and could see some dampness in the exhaust manifold after removing the muffler. It does not have the sweet smell of coolant and there was no visible steam coming out of the exhaust stack. Not sure if this is related or not.

Is it possible that the leak will only rear its ugly head when the engine is running because of some force or vibration? Any help is greatly appreciated!

-Ed

Hi Ed,
seeing you are not seeing any leakage inside the engine with a pressurised system--on the off chance maybe check that the water pump weep hole is not blocked--water pump seal maybe could leak in operation so if the weep hole is clogged it would then pass into the engine but only when the shaft is turning if the water pup bearings and seal are suspect.
I stand to be corrected.
The C's we have in Australia come from Japan and have the big bore D330 engines--they have a Chevy 6 pressed tin type valve cover and a gear driven water pump on the timing gear cover.
If yours has the older small bore D330--cast aluminium valve cover--then they have a belt driven water pump and makes what I said above redundant.
Cheers,
Eddie B.

Seems suspiciously like leaking liner seals. Requires operating temperature and liner vibration for leakage at this point. Might try a coolant sealer and see what affect it has.

Thanks for the recommendations guys.

erb - I had already checked the water pump weep hole, was really hoping it would be that simple, but no such luck.

Old Magnet - I was thinking along those lines as well. I hate to use stop leak, but in this case I am leaning more and more towards going that route.

I have used Bars Leaks before in an automotive radiator emergency with good results, I am going to do a little research on the different types available these days and what may work better for a liner seal leak as opposed to a radiator leak. Anyone have any recommendations? I really don't want to end up plugging up the radiator cores!

I use the Bars Leak Silver stuff and seems to be ok. I think it was ccjersey on here that recommends a product called"Dike".

You might try rolling the engine over by hand keeping pressure on the radiator,
liners have been known to pinhole.
Bob

I did rotate the crank 180 degrees by hand when the injectors were out and saw no change

I would probably have a go at replacing the oil cooler if this is the same as the 3304 on the D4.
Have had oil coolers, both engine and trans, that at 6-7 bar air pressure will not show a leak, yet when at operating temperatures will tranfer fluid.
Its a simple at relatively inexpensive start before tearing into the deep end.

If the oil cooler had a leak, wouldn't I see oil in the water as well since the oil pressure is greater than the water pressure when running? If it is possible they will sometimes pass water to oil and not oil to water, I may try replacing it before going the "stop leak" route.

"Curly71" wrote:

If the oil cooler had a leak, wouldn't I see oil in the water as well since the oil pressure is greater than the water pressure when running?.

One would think so, but I have seen more than one case with these coolers of water in oil but not the other way around.
And even if you decide not to replace the cooler, its a good opportunity to cĺean the crud out of the tubes and at least try to test for leaks at a higher pressure.