M923A0 coolant in oil ... it's rebuild time for me!

[manders]

Hello to all!

Long story short ... a handful of back-to-back lengthy out-of-town work assignments had my truck sitting for too long, and when I finally got around to givin' it a little love, I ended up with coolant in the oil. It was discovered during a "routine" fluids change, and the mechanic sliced open the filter and found pieces that he assumed were liner.

[NOTE: I'm not going to try and excuse my irresponsible behavior, it was a dumba$$ rookie mistake. Hopefully, the large dent in my wallet will serve as a great dissuader of a future recurrence. ]

I've read a bunch of the the posts describing similar situations, and while I haven't yet dropped the pan, pulled the heads, etc., to gauge the full extent of the trauma, I'm leaning towards doing a complete 6 cylinder in-frame rebuild anyway, rather than just a cylinder or two, mostly 'cuz I've read a couple stories of guys doing a partial, and then 6-9 months later doing it again!

I've got time off for the holidays to do the work, and by a happy coincidence of timing, I will be able to employ the services of a friends' son who is a heavy equipment diesel mechanic with a wee bit of experience on the 855 engine.

My apologies for the rambling intro ... on to the questions!

As both my time and my "Soldier B" time is limited, I want to get all the parts ordered in advance. I found the "3801795" Piston, Liner, & Ring kit part number in the 5ton6x6PartsReference.xls spreadsheet, and sure enough, a Bing search returns a handful of places selling the in-frame rebuild kit which references that number (probably all from Interstate-McBee), but they also need the rod and main bearing sizes. Are these both "standard" for our vehicles?

Aside from the rebuild kit, is there anything else I might want to acquire in advance, which might have a long lead time and/or merits replacement at this same time? Seeing as I already got the dang thing apart and in couple hundred pieces anyway ...

My evenings are being spent plowing through the TMs and this site, but any and all additional guidance is welcome and appreciated.

Thanks.

MAnders.

 

[simp5782]

Is the truck running bad at all? A bad oil cooler can cause the same symptom of coolant in the oil. Sometimes it puts oil in the coolant.

Will Wagner will be along here shortly to give the expert opinion on a rebuild. I have takeout small cam engines for $1200. Shipping might be a little high.

Or go ahead and bite the bullet and put a big cam 350 or something along those lines and less desirable on the market of the big trucks for a little more than what a rebuild would cost you. Plus you get the extra power.

 

[porkysplace]

Is the truck running bad at all? A bad oil cooler can cause the same symptom of coolant in the oil. Sometimes it puts oil in the coolant.

That doesn't usually leave pieces of metal in the filter though.

 

[simp5782]

That doesn't usually leave pieces of metal in the filter though.

Oil coolers are made of metal. i have had a few blow holes right in em and the metal returns to the oil pan and gets sucked up. the NHC250 has a screen on the suction line for the pump so be hard for anything other than really small stuff to get to the filter.

 

[manders]

I was able to drive it to the mechanic, and aside from what I ***thought*** was a slightly louder than normal diesel 'clunking', there was a decent amount of blow-by coming out of the crankcase breather tube once I stopped.

When the mechanic drained the oil, it looked like malted milkshake, so he seemed to believe it was more than just secondary traces.

I had thought about just doing an engine swap, but the cost seemed to be a bit more than a rebuild, especially since a) I've got a helper who is smarter than me, and b) I'm going to get a chance to learn A LOT more about what makes these things go!

 

[simp5782]

I was able to drive it to the mechanic, and aside from what I ***thought*** was a slightly louder than normal diesel 'clunking', there was a decent amount of blow-by coming out of the crankcase breather tube once I stopped.

When the mechanic drained the oil, it looked like malted milkshake, so he seemed to believe it was more than just secondary traces.

I had thought about just doing an engine swap, but the cost seemed to be a bit more than a rebuild, especially since a) I've got a helper who is smarter than me, and b) I'm going to get a chance to learn A LOT more about what makes these things go!

I could ship you a core short block assembly for rebuild if you wanted it for free. Just cover the shipping. It is a red river rebuild engine that dropped a valve and popped a piston. would give you something to rebuild before taking yours out so its a pretty quick swap. just swap your heads and everything else. For what a Big cam 300 or 350 cost at around $2500 on ebay I would go that route for the work involved. it is well worth it.

 

[manders]

I could ship you a core short block assembly for rebuild if you wanted it for free. Just cover the shipping. It is a red river rebuild engine that dropped a valve and popped a piston. would give you something to rebuild before taking yours out so its a pretty quick swap. just swap your heads and everything else. For what a Big cam 300 or 350 cost at around $2500 on ebay I would go that route for the work involved. it is well worth it.

Let me have a chat with my Soldier B "helper" ... I might just take you up on this offer!!!

 

[manders]

I found the "3801795" Piston, Liner, & Ring kit part number in the 5ton6x6PartsReference.xls spreadsheet, and sure enough, a Bing search returns a handful of places selling the in-frame rebuild kit which references that number (probably all from Interstate-McBee), but they also need the rod and main bearing sizes. Are these both "standard" for our vehicles?

Are these both "standard" for our vehicles?

Aside from the rebuild kit, is there anything else I might want to acquire in advance, which might have a long lead time and/or merits replacement at this same time?

Anyone? Anyone? Bueller?

 

[doghead]

If your motor has bean rebuilt it should have a tag/label on it showing if it has standard sized rod and mains, or not.

 

[manders]

If your motor has bean rebuilt it should have a tag/label on it showing if it has standard sized rod and mains, or not.

Would that be the Cummins data plate attached to the engine below the power steering reservoir? If so, I'm gonna need a strong pair of reading glasses ... ;-}

 

[doghead]

No, I'm refering to a military applied rebuilt tag on the side of the block.

 

[doghead]

It will be similar to this, typically on the passenger side of the block.

 

[simp5782]

It's on the bell housing at the rear of the engine if it has one. If not pull the pan and see what is stamped on the crank or rod caps

 

[manders]

It will be similar to this, typically on the passenger side of the block.

Thanks for sending the pic, it helps. Unfortunately, nothing like that ...

 

[manders]

It's on the bell housing at the rear of the engine if it has one. If not pull the pan and see what is stamped on the crank or rod caps

Nothing there either. I guess I'm getting dirty tomorrow ... ;-}

 

[doghead]

There will not be any tag like that if your motor was not rebuilt by the government.

It is usually pretty obvious if there is a tag.

No tag just means your rods/main and bore is standard.

 

[manders]

There will not be any tag like that if your motor was not rebuilt by the government.

It is usually pretty obvious if there is a tag.

No tag just means your rods/main and bore is standard.

This is excellent news! I'm still going to do another thorough look-around, just to be sure I didn't miss anything.

Thank you!

 

[WillWagner]

I read thru this, saw no troubleshooting. A freeze plug in the top of the head will but coolant in the oil, a fast easy fix. If it is apart, well, guess you better check things over very carefully or you Will be doing something over again. How far torn down is it?

 

[manders]

You are correct, I briefly mentioned in my original post that I haven't yet dropped the oil pan, but I'm gonna find the time to do that any day now ...
The original diagnosis was performed by a heavy truck diesel shop in North Bend, but the rate he quoted to prepare a "complete" diagnosis and repair estimate was over $2000. I figured I'd better off doing it myself. That way, at least, I'm teaching myself to fish!

A freeze plug in the top of the head ...

I recall very clearly rivercreek's thread https://www.steelsoldiers.com/showt...e-and-Fix-Unusual-Cause-Coolant-Leak-into-Oil and believe me ... I would like nothing better than to have that be the problem.
I'll definitely report back once I've got the pan off.

In your experience, would you agree that that the absence of rebuild tag is a very good indicator that the rod and main bearing size is Standard?
I bought this truck from JBLM back in 2013, so I'm the only owner ... if you ignore all the maintenance units who've had their way with it since the original paint was shiny ... ;-}

 

[WillWagner]

Unknown on the bearing size, but if/when you drop the pan, look on the #1 rod counterweight. IF it is not torn apart, do like you said and drop the pan, use a cooling system pressurizing tool and put 15 or so PSI on it and watch where the drips come from