M923A1 Coolant in Oil

[sd39u]

Went down to the shed to do some minor work on my M923, replaced the oil pressure sensor on the motor and the oil pressure gauge on the dash and put a new mirror on the truck. Easy enough right?

Before I started the motor, I did my usual checks of the oil and coolant levels. Noticed that my burp tank was not as full as the last time...hmmm. Checked the oil...black as could be...hmmm. Fired up the motor for the first time in 30 days and had lots of smoke so I wasn't initially concerned as we've had a lot of rain and there was probably a lot of water sitting in the muffler. I let the truck idle for about 5-6 minutes to build air while I did some other chores.

Came back to the truck, exhaust has a faint grey color to it. I figured I'd take it down the road 2-3 miles and come back to make sure everything is all OK. I get back to the shed and notice that the truck still has that faint grayish exhaust. I shut the truck down, wait about 15 minutes to let it cool. Checked the burp tank...just a hiss of steam...tank is empty...crap. Check the oil...it's all milky white...double crap. Checked the oil fill...milky gunk everywhere...triple crap.

I'm probably going to have the truck towed to the same shop that did my engine swap about 45 days ago. I'm not going to risk seizing another motor. It's only a 8 mile drive.

So...fellow 5-ton owners:

Head gasket?
Oil Cooler gasket?
Cylinder liner?
Cracked block?

Looking for some advice/help here.

Thanks!

 

[osudieselguy]

It's deja vu all over again. Just finished my in-frame rebuild in june with similar problem. The initial cause of coolant in the oil is the O-ring seals of the cylinder liners (wet sleeves). No mystery here. The real puzzler is why. My NHC-250 had a piston meltdown and o-ring failure. Could have been the injector creating a hot-spot (poopie fuel), could have been poor install of the liners (recent rrad rebuild). In any case, the piston went mushy, the piston rings disintegrated, the crankcase filled with oil, the coolant-water-milkshake ruined the rod and main bearings, the hard ring bits damaged the 1-2 head, and I got a long-term project. Check out my pix on my earlier post.
Advice? Don't run your motor. Drain your oil, drop the pan. Put some water in the coolant tank. Crawl under with a flashlight, see where the rain comes from.

 

[sd39u]

Well. Big Dog is on his way to the vet.

 

[JohnnyBM931A2]

View attachment 576453
Well. Big Dog is on his way to the vet.

 

[Vintage iron]

Good thing you caught it. Cummins hate to be lugged and the Allison will bring the RPMS to low. Always keep the RPMS between 1500 snd 2000. It was probably the o-ring at the bottom of the liner. Mine did the same thing. But I put a Big Cam 290 in mine

 

[osudieselguy]

Let us know what the doctor says.

 

[sd39u]

Well...it's taken some time...but we now know what was wrong. Good news is it's fixable. Lots of moisture in the top end of the motor, but none present in the oil cooler. I must have caught it real fast.

Definately had a blown head gasket on cylinders 3-4 and 5-6. Contributing to the issues were a bad injector on the #5 cylinder which in turn created its own set of issues. Then sleeve is all scarred up so I'll be putting a new sleeve, rings and injector in that hole. The rest of the motor looks good from the top end.

We'll get all that done and put some fresh fluids back in and we should be back in business! This will probably mean that Big Dog won't get painted this fall...but at least it'll get me to deer camp and back!

Eric

 

[MWMULES]

Man Eric some how I missed this when you first posted. Saw Jim this weekend at the air show and he told me about it. I hope this is the last of your woe's on owning a MV.

http://www.steelsoldiers.com/showthread.php?141648-M923A1-Engine-Swap-Progress&highlight=

 

[sd39u]

I'm ready for some good luck.

Bad motor...replaced...followed by head gasket and bad injectors...

I could have bought another truck for all this $$$$

 

[sd39u]

Big Dog is back home. My pocketbook is empty. but we are back in business and hoping for no more major ailments. My wife is about ready to kill me!

 

[JohnnyBM931A2]

Big Dog is back home. My pocketbook is empty. but we are back in business and hoping for no more major ailments. My wife is about ready to kill me!

I'm still a little confused about one thing.. You mention doing a previous engine swap in the truck. Was it a used engine, or rebuilt? If rebuilt, shouldn't the shop/engine rebuilding company be held responsible for the engine failure?

 

[sd39u]

You read correctly. First motor went to crap...then I bought a takeout motor from a guy here on the site that was scrapping out a truck. The replacement motor made it about a month before the head gasket blew out. Discovered a bad cylinder sleeve once we got the heads off...then replaced the sleeve, piston and rings. Also discovered some bad injectors. Basically, we did a mini in-frame rebuild of the motor to insure we don't have any more issues!

I'm still a little confused about one thing.. You mention doing a previous engine swap in the truck. Was it a used engine, or rebuilt? If rebuilt, shouldn't the shop/engine rebuilding company be held responsible for the engine failure?

 

[JohnnyBM931A2]

You read correctly. First motor went to crap...then I bought a takeout motor from a guy here on the site that was scrapping out a truck. The replacement motor made it about a month before the head gasket blew out. Discovered a bad cylinder sleeve once we got the heads off...then replaced the sleeve, piston and rings. Also discovered some bad injectors. Basically, we did a mini in-frame rebuild of the motor to insure we don't have any more issues!

Geez.. That's rough. Forrest Gump says "used engines are like a box of chocolates... You never know what you're gonna get.." Shame you guys didn't end up rebuilding the replacement engine before you put it in the truck