250 Cummins Engine

I purchased a M817 from GSA. The engine is locked up. The starter works but engine will not turn. I pulled all six injectors so it is not hydrostactic lock. The rocker lever housings looked like new. I'm now working on pulling the pan. There is no evidence in the oil of any water. There seems to be no way to get a tool on this engine and attempt to turn it backwards to see if it will move.
Has anyone had any experience with this king of problem? Also, anyone know where I can get a manual on just the engine?

Thanks
Dennis

I have heard some guys put the truck on a hill in gear and squirt some marel mystery oil in the cylinders, then wait. I have heard it works from more than one source. One day you will go back and it will be at the bottom of the hill, freed up.

Re: RE: 250 Cummins Engine

gimpyrobb said:

I have heard some guys put the truck on a hill in gear and squirt some marel mystery oil in the cylinders, then wait. I have heard it works from more than one source. One day you will go back and it will be at the bottom of the hill, freed up.

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Make sure your house and anything else you value is not at the bottom of this hill before trying Gimpy's method.

RE: Re: RE: 250 Cummins Engine

you cant put a pry bar thru the bellhousing inspection hole and turn with a lever?

RE: Re: RE: 250 Cummins Engine

Use the nut on the accessory drive pulley. I might have some manuals on the engine.

Hey Turboman,
The TM for the nh250 cummins is in the tm section on the 1st page.

http://www.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=218

Tony

Turboman,
The teardown and assembly is located in 9-2320-260-34-1. This is available here in Tech Manuals.
Good luck......

I know you can use a Barring Tool to turn over a Cummins B and C series, but I'm not sure about the 855. Will?

put a pipe wrench on the harmonic balancer make the wrench as tight as you can to keep from damagein the balancer it shouldnt take much effort to turn it if it does prolly aint good make sure that the tranny aint locked up before ya get real involved make sure the clutch and locked up too 855 cummins r bad to stretch head bolts and then leak water into the cylinders if they arent replaced with new ones if it was parked like that it could have locked it up good luck

NO, don't pry on the damper...unless you like broken camshafts. Get yourself a 3/4 drive ratchet, a 1 1/8 or 1 5/16 socket...depending on what it's built with. The engines used in the military trucks were a hodgepodge of stuff, some old style, some new style. and try to bar it over by the accessory drive pulley...the nut in the center of the pulley that is in front of the air compressor. If it won't turn with the injectors out of it, It could be rusted, or have a spun bearing. Take the oil filter out and see if there's metal in the media.
HTH, Will

if ya break the crank by turnin it with a pipe wrench id say ya need a new crank anyay as i said perveously it shouldnt take much effort to turn the engine over with the pipewrench ive worked on alot of 855s and own one it wont hurt anything and its the easiest way to do it if ya put a ten foot pipe or something on it and try to turn it ya might break something

Tony; I had reviewed that manual and it is for the new Cummings engine and 939 series 5 tons. This ia a M817.

OK, let's review...... This ' . ' is a period. It ends a sentence.

I had a boat motor 350 gas that was locked up tight. I used a lot of spray oil and a huge prybar through the crankshaft and rocked it back and fourth it finally freed up my guess was condensation locked the pistons by rusting the walls because after getting it free it ran good

armyman more than likely hit it on the head, common problem in 800 and 900 series that sits a season or more, if they are not moved, started or fogged prior/during storage, guess what will happen, the rings will sieze to the walls, making it difficult to get turned over, i personally go out there with a can of wd40 and have at it, do it on a friday come back monday, let it free crank with the injectors out, put it all back together reprime the injectors and once you got it running, be sure to change your oil as id bet it has a large amount of condensation in it.

Alternatively...if you personally never started the truck yourself...and this is HIGHLY unlikely, the dowel pin inside the timing cover backed out and fell into the guts...thats a bad bad thing and im still not sure if that isn't just the dowel pin on the 900 A2 5 tons...since that motor is much like the B series with that particular dowel pin that sometimes grenades dodge pickups.

Im under the assumtion and always pull, plugs/ injectors of any motor that has thought to not have been turned over for a year or more, and spary some luby in there too, I do it with the boats every year too, the Mil trucks I run every couple of weeks for half an hour or so at least once a month, I used to pull the bats for the winter, but now leave em on the maintainers, may make no sense for this thread but it made me think of this, Randy

Break fluid works wonders in stuck cylinders, the real stuff not "sillycone"
I had a D-4 Cat that had sit in the rain for years, poured a gallon of break fluid in the exhaust, intake and the same for the pony starter. 30 days later it started, blew break fluid every where but ran.

I have always had good luck with Marvel Mystery oil, and brake fluid. We freed up several engines at the railroad museum that way, one was an engine that sat buried up to the running boards in sand for about 20 years, did the MM oil in the cylinders for a week, barred it over, than she cranked right up. But you have to do that with the injectors out, or you will just hydrostaticly lock it when you bar/crank it over. I know it should be obvious to most of us, but we had 'trained' diesel mechanics on the ship try again and again to start a hydrostaticly locked engine until the air starter flew off and the flywheel shattered. Boy was that fun! you think it's hard separating a Multi from a tranny, try a 12 cylinder Alco 251C, and a 2,000Kw generator! Then line everything back up and get them matted back together again! Whew, long nights on that one!

I had a rebuild that came in for a simple oil change. After the change it wouldnt turn over. Tried to bar the motor over both directions and no movement at all. after a tear down found a washer jamed between the timming gears. Someone was not very carefull during the build.

quarkz said:

Hey Turboman,
The TM for the nh250 cummins is in the tm section on the 1st page.

Steel Soldiers

Tony

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I never realized how well made the NHC250 is until I read the parts manual.