Water in oil in M925A1 - New addition

[Truckoholic]

So I just today finally bought me another M925A1 after a three year hiatus of not owning any military vehicles. I bought a house and property here in northwestern Oregon a year and a half ago, and there was no extra money or time to be messing around with military trucks for a while. ha ha
But here lately I'd been dying to get my hands on another M925, so I started scanning craigslist, and the auction sites, and finally came across one for a good price not too far from me. Went and looked at it, and ran it a little today, and decided I definitely wanted it for the price asked.
It is a 1987 M925A1 that was rebuilt in 2005 and has 2,300 miles showing on the odometer. So it's in really good shape. Has ABS and the spare tire rack and crane together with new spare tire which I was happy to see. It has really nice 14.00-R20 tires on it. The guy I bought it from, bought it 3 years ago to turn it into a water truck, had it hauled from the base to his house, and there it sat ever since. Well, he's moved it around his yard now and then, but when he discovered the water in the oil, he didn't run it much anymore, and then after a while decided to sell it.



So, the water in the oil doesn't concern me so much on that particular engine. I have read multiple threads here in the forums using the almighty "search" feature, and have learned a lot about the usual culprits such as the oil cooler, and cylinder liners, and freeze plugs in the heads. While I was there looking at the truck, I pulled the oil cooler off to look at it, and it did look quite corroded and very clearly a possible suspect. But I covered one of the oil passages and blew into the other one, and could not detect any air escaping through the water passages. But the reason I highly suspect that that probably is where the problem is, is because when I took one of the coolant lines off specifically to see where the water level in the engine was, to get an idea of where the problem is, the water level happened to be right at the level of the bottom of the oil cooler. So I'm pretty sure I can rule out freeze plugs in the heads, or cracked heads or head gaskets. The water level was right smack, level with the lower part of the oil cooler. Which would make perfect sense if there is a hole in it, and the truck sat there slowly leaking water into the oil pan through that hole. And over years, of the truck sitting there, it could have leaked through a hole that I couldn't detect by blowing on it.

But what sucks is....I also realized that the oil cooler sits at about the same level as the cylinder liners do. So if there is a hole in a cylinder liner, or bad cylinder liner o-ring, I am guessing the water would have been about the same level. I'm trying to look through the TM's for that engine to see if there is an exploded view of the engine, that shows the water passages, so I can verify that the water level would be at the same spot whether it was a cylinder liner, or the oil cooler that was bad. I'm having the truck hauled home, since I don't know yet where the water is coming from. I am tempted to bring new oil, and changing the oil where the truck sits, and put more water in and drive it the 180 miles home, and hope it is just a small enough leak that it would make it home fine, but I don't want to take that risk, and want to just have it hauled home and take the oil pan off, pressurize the cooling system, and see where the water is really coming from.

Had I been able to verify that the oil cooler did indeed have a hole in it, I most definitely would have just ordered a new oil cooler core, and taken that, together with what I needed to change the oil, and gone up there, and changed out the core, changed the oil, added water, and would have driven the truck home with no worries. But since I was not able to tell by my blow test, that the oil cooler core was indeed the culprit, I figure it's safest to spend the thousand dollars to have the thing hauled to my shop.

But do any of you happen to know what page, or have a picture, or have any independent knowledge yourselves as to whether the water level in the engine would indeed be at the same level whether it was a hole in the oil cooler core, or a cylinder liner problem? Looking at the outside of the engine, it appears the cylinder liners and the oil cooler are about the same level, but I've never had the liners out of an NHC250 before, so I don't know exactly what level on the engine the water jacket is, in relation to the oil cooler.

Anyway......... I've very excited to finally have another military truck! This will be the 5th one I've owned, but the first one purchased from a private party and not through GL. Yet at a GL price. haha. I've got a turbo, and exhaust manifold off a 350 cummins I've been holding onto for years now. I intended to put it on my last M925A1, but never got around to it. So after I get the water in oil thing figured out, that's one of the first things I plan to do to this truck. Put the turbo on it, and then straight pipe it. The paint is nice enough that I don't think I'll feel a need to sandblast it and repaint it like I did all of my other ones. And this one I plan to actually keep this time. That's what I said about my last one, but that didn't last long. ha ha. They are just way too easy to sell for a profit after they are all fixed up nice. So I think the key to keeping it, is to just not fix it all up nice.

 

[Carlo]

Does it get cold enough to freeze where the truck was parked? I'd test the anti freeze to see if it was working to spec. I'd also drain it and just see how much water is in the pan. Could be the water got there from an 'outside source'? Would thing I would not do is drive or start it till I was sure. The 250 is a old design tried and tested and tough. I'd be surprised to see a cracked liner or head BUT I've seen one thing not very often in the past, pin holes in the liners. It came from lack of non correct anti freeze and electric charge of the motor mass. A combination of the 2 factors made pin holes in the liners..
Have you started it even for a few seconds? Blow by at the dip stick? Blow by at the oil filler on the rocker boxes?

 

[1 Patriot-of-many]

I'm doubting it's the oil cooler. You'll see oil in the coolant. Oil pressure is much higher than coolant pressure. I recently changed my oil cooler because of that reason. It came from the NG with oily looking coolant, sure enough when it heats up oil gets pumped into the coolant causing the coolant to overflow oily coolant.

 

[Truckoholic]

Yes it does freeze where the truck is parked. Not a whole lot, since it is close to sea level in Washington state, but it does freeze. However, the coolant has sufficient anti freeze in it that freezing shouldn't have been a problem. The reason I suspect the oil cooler, is because this truck has been parked for years. So the reason there is no oil in the coolant, is most likely because there was no water in the oil cooler for the oil to mix with the last time it was run. It might have just sat there slowly dripping down into the oil over the years.

Yes I did run it for just a little bit after making sure the oil seemed to be sufficiently lubricant for a short run test. And there was no blow by out the oil filler cap or dipstick.

One dilemma I have, is I live out in the country, but on a road that is not lowboy accessible. So the trucking company is going to have to drop the truck off for me about a half mile from my house, and I'm going to have to go make sure the truck is up to making the short drive to my shop. If it's just a slow water leak, or if it really is the oil cooler and is going to be putting oil into the water during that short drive, that's fine. I'm not worried about that. It's not going to hurt anything at all for a little oil to get in the coolant during that short drive home so I can fix it. And if more water is slowly going to get into the oil during that short drive, I'm not worried about that either. But if a cylinder liner is bad, and I go adding water to the radiator, and hydrolock a piston, THAT is bad. So that's why I'm hoping to get a better idea before the truck gets delivered next week or whenever, what the chances are of it being a cylinder liner.

I still highly suspect the oil cooler given the circumstances of the problem being that the water apparently slowly drained into the oil as it was sitting parked. And not that it got there while it was running. Had the radiator been full, or close to full, when I got there, I would have suspected water got into the oil by some other means, like rain or something. But since there was so much water missing from the radiator, AND grey oil 3 inches over the full line on the dipstick, it seemed pretty obvious that there was an equal displacement of fluids.

 

[lindsey97]

When it is delivered not running, cage the brakes and drag it but sure you can stop it with whatever you are pulling it with. They weigh around 22,500 lbs. Or get some air fittings and a small portable compressor, plumb the compressor into the truck air system, place the compressor in the truck bed and drag the truck with someone driving and then you will have brakes.

I changed the oil cooler element in my M923A1 in april 2014. I was getting oil in my antifreeze. Hopefully you are correct in that assuming it is the oil cooler leaking and the coolant is bypassing at the oil cooler when the motor isn't running for all of those years, that would be an easy fix.

If by chance you do have to drive it as is, drain the radiator, fill it with distilled water only, and change the engine oil/filter, then make a run for it to the house. Water won't hurt your engine short term like ethylene glycol will.

 

[wreckerman893]

Cummins engines that have not been ran in a long time often do this. I had a buddy that bought two M915's that had been sitting up for years. They had the 400 Cummins in them. He got them home and both cranked and ran good. Two days later both of them had water in the oil. He explained the problem to me and it has to do the the piston sitting in one position for so long. He ended up scrapping both trucks out.

 

[machinist75]

Mine cracked, whole oil pan full of antifreeze.

 

[Scar59]

Mine cracked, whole oil pan full of antifreeze.

Been watching this thread, had a low mileage M931A1, cracked #3 liners, ran good, made a little steam, you could smell the coolent in the exhaust.
Good luck
JC

 

[Truckoholic]

Well..........Found the source of my water in the oil Went up to where the truck sits today to change the oil, and see if I could make the thing road worthy enough to drive it home. When I took the oil drain plug out, I found only the normal tiny bit of metal substance stuck to it like you would find on any good condition diesel engine, so I was quite happy about that... But after the oil drained out, I decided to stick my finger in the drain hole and feel around, and to my horror, I felt multiple large chunks of cylinder liner, together with multiple cut up chunks of cylinder liner o-ring. DAGNABBIT!!!!! What do you guys suppose the chances are of the liner being destroyed to that extent and the block still being good? I'm betting slim, with that connecting rod and piston bashing around in there, and who knows how long it was run like that. But, I'm having it hauled to my place, and will drop the pan, and look up in there and asses the damage.

 

[Carlo]

Wow I did not expect this kind of damage. Didn't the previous owner drive it around some?
Sorry about this news. I would think if you have liner pieces in the pan as you say then metal parts have circulated throughout the oil system.
I've seen cheap complete motors on the site that might be worth looking at before considering rebuilding a motor that has chunks of metal in the pan.
I wish I lived closer to you. Together we could swap out the motor in a day.

 

[Truckoholic]

I wish I lived closer to you. Together we could swap out the motor in a day.

Yeah, I am really curious to get that oil pan off and try to see what happened up in there. I can't understand why that would have happened. And yeah, what sucks is I currently have no way at my shop to lift the old engine out, and a new one in even if I did find a replacement engine if I need to go that route. I used to live close to my parents and had use of my dads big John Deere backhoe for those kinds of things, but now I live 500 miles away from them. Yeah, there is no telling what damage is done to the inside of that engine block. Last time I had a cylinder liner and piston come apart on and engine, it was on my 8V92 Detroit in my 67 Kenworth, and the connecting rod punched a great big hole in the side of the block after annihilating everything in it's path inside. This engine did still have 40 psi oil pressure at idle according to the pressure gauge when we were running it the other day before I knew the extent of the damage. So, I don't know. Maybe there's some chance is it salvageable.

 

[mikey]

Sorry it didn't go as well as you hoped.

Looks like you need to buy a wrecker to get that engine out

Mikey

 

[Sephirothq]

I have an engine in pa for that truck. It is a bit far away from you. Some guys would repair what you have and some would replace it with a different one.

 

[machinist75]

Mine busted off at the bottom of the liner on the #5 cylinder where the water passage was. The motor was running fine would have never known anything was wrong till I changed the oil.

 

[Truckoholic]

Mine busted off at the bottom of the liner on the #5 cylinder where the water passage was. The motor was running fine would have never known anything was wrong till I changed the oil.

I'm really hoping something like that happened and that the block is okay. That would be very nice. But what scares me, is because I also was able to pull through the oil drain hole, pieces of liner o-ring.....both orange and black pieces, indicating both top and bottom o-rings as if the entire liner broke up and came out.


There she is, loaded on a trailer headed my direction right now. Can't wait to get it here and get that oil pan dropped and see what kind of mess I'm really dealing with up in there.

 

[Carlo]

I know what your feeling. I've been there before. Hope you find little damage.

 

[todds112]

That's a good looking truck. Hope it works out OK for you.

 

[Truckoholic]

Well, the truck got delivered this afternoon. Went great! Used an air hose I made up to charge the air brake system using the delivering trucks air system so that we could offload safely with foot brake even though the parking/driveline brake was working good. Then used my Chevy Suburban to pull it off the stepdeck trailer. Then the truck driver was a really nice guy who offered to help me get it to my house which was about a half mile away from where I had him drop it off. Because I knew there was no way he was getting up the driveway to my house and shop with his truck and trailer. So first I drove my suburban and he steered the M925, til we got to my driveway, and since there was no power steering, he was having a hard time getting the truck turned sharp enough to make the sharp 90 degree turn, so I had to unhook, and pull the truck backwards to get another go at making that sharp right turn, and I steered it this time. So got it back to my shop, and used my suburban to pull it into my shop so I can start working on it. Real anxious to get that oil pan off so I know what I'm dealing with.

 

[Truckoholic]

Well here's what I found.

Dropped the oil pan this evening..........and discovered that sure enough, only the bottom section of the Number 6 cylinder liner broke off, so I did not have a wild, uninhibited connecting rod and piston bashing around in there. I am so incredibly relieved! All of the other liners, and bottoms of the other pistons appear to be in good shape. It's just number 5. Thank heaven!!!! So I'll be replacing that. Although according to some other posts here on Steelsoldiers, it sounds like my excitement might be for nothing. Since some guys say there is a reason the bottom of the liner broke off, and the engine most likely has more problems. I sure hope not. Also, it had anti-freeze mixed in with the oil for who knows how long, and yes it had been circulated through the engine. So, I guess when I go to replace this piston and liner, I'll look close at the journal and bearings, and see how they look. Not looking forward to doing a whole rebuild here.

 

[elkhtr]

Piston and liner kits can be had for around 100.00. Pull what's left of it, if it doesn't show large amounts of cavitation erosion replace it and be on your way. Either way you go, repair or replace , it's not as bad as you'd think. Follow the technical manual, next thing you know you're done.