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

  1. #31
    Moderator WillWagner's Avatar
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    Use a small wire brush to clean the deck around the liners so you don't f-up the fire ring. Clean and dry, that does not mean shiny, stained blocks are normal.
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  3. #32
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    Quote Originally Posted by WillWagner View Post
    Was what was in the oil coolant or plain water?
    A little more history of my ownership ...

    I purchased this vehicle from the JBLM branch of GovLiq in Fall 2013, and it came from W8BA UTES of the Oregon National Guard. It showed 24035 miles when I bought it, and 24370 now. (Like the proverbial little old lady ... I only drive it to the market once a week ... )

    It drove off the lot at JBLM about two miles away to a local mechanic for a quick once-over where it was pronounced road-worthy for the 50 mile drive to my home. About three months later, it developed a coolant leak while out for a leisurely Saturday stroll. I had it towed to another mechanic nearer my home for a complete stem-to-stern review, including changing of all fluids, and it passed with flying colors.

    After that, I did short monthly trips for a couple of years, mostly Cub Scout-related local outings, and then work intruded on my hobby and it spent way too much time unattended and gathering dust.

    In April of this year I took it to yet another mechanic for yet another stem-to-stern, in preparation for a long drive eastward to Spokane. That's when all the current issue was discovered.

    Here is the most-recent mechanics' diagnosis:

    MechanicDiagnosis.jpg

    I was billed for 9 gallons of oil, which is just about what came out. I didn't see the original waste oil, but here's what I drained this time around:

    DrainedOil.jpgDrainedOilAfterQuickSwirlLikeWhatYoudDoToA1995Bordeaux.jpg


    Quote Originally Posted by WillWagner View Post
    See those fiber white rings? One of the things to look for when a head gasket is thought to be a problem, is to look at those grommets AFTER you pull a head. The grommets SHOULD stick to both the head and the deck, the grommet rips in half when the head/gasket is removed.
    I dug out my 3x reading glasses and found that 12 grommets showed obvious indications of being ripped, but the remainder were left seated in the block and looked to have a pretty smooth top surface. (I don't know if it's relevant, but the 5/6 head had more ripped grommets than the 1/2 or 3/4 head, which also appear to have less sealant present.)


    Quote Originally Posted by WillWagner View Post
    BE CAREFUL when cleaning the block so you do not remove/knick the fire ring.
    How prominent should the fire ring be, and is it at the outer edge of the block or closer to the pistons? I ask because I took a soft cloth and cleaned up the least grubby area of the block and could not feel any distinct line.

    Quote Originally Posted by WillWagner View Post
    No type of sealant should be put anywhere on the head gaskets or surfaces....for that matter on ANY cummins supplied gasket...NO SEALANT
    So ... did someone mistakenly put sealant between the block and the gasket, or am ***I*** mistaken in thinking that this rubbery orangish/reddish stuff is gasket maker/sealant?


    The net/net is that I am very eager to understand whether the mere presence of this ... gunk ... floating around the inner-workings of this engine is its' proverbial death sentence, i.e., would swapping in a different engine be cheaper than pulling this block, yanking everything else, then getting everything 'sonic-cleaned, etc.?

    Or should I just button everything up, replace all the fluids, spin 'er up and do a "hearty" 30 minute shakedown tour, and then drain the oil and see what surprises I find?

    (BTW ... we pulled one bearing to check for scoring and it looks/feels pretty clean, and we'll do the same for the others just to make sure that they didn't suffer too badly as well.)

  4. #33
    Moderator WillWagner's Avatar
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    There is some srt of sealant on the deck in your pictures, I am color blind, but it looks like it could be copper coat, a spray on copper coating, I think Permatex makes it. Whatever, it shouldn't be there.

    The fire ring is on the liner, about half way between the outer edge and the raised part that is the top of the cylinder.

    The report says that water was added and it went into the pan, piston debris in the filter media. The mechanic suspects melted liner packing and scored cylinder....that will melt the packing. You pressurized the system and found nothing dripping on the ground. If/when a cylinder scores bad enough to transfer piston material to the liner, there is usually a very noticeable knock that you can short out by shorting the injector and, it creates smoke in the crankcase, this can be seen when the engine is still cool, coming up from the push tube cavity of the failed cylinder, if the engine warms, the smoke is everywhere. As it sits now, troubleshooting is out of the question, you need to look carefully at things.

    Since the guy at the shop thinks it is melted liner packing due to scored piston and found pieces parts in the filter, that is an easy inspection since the heads are off. All of the liners should appear to be shiny grey color and you will see honing cross hatch in them. There should be no grooves top to bottom and they will be smooth as glass. A scored cylinder will be rough, have wavy lines top to bottom, they usually are around 2 inches below the ring land area of the piston because the skirt swells and not the crown of the piston, you will need to bar the engine around to get each cylinder at BTC to get a good look at the liner.

    What bearing did you inspect? Rod bearings determine the condition of the mains, the lower shell will show no wear, only the upper. The bearings in the 855 are a lead/tin overlay, the coolant attacks the overlay and pits it. SOME pitting is OK for reuse, some not. I think I still have a reuse guideline book around here, let me look.
    Last edited by WillWagner; 12-15-2018 at 11:48.
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  6. #34
    Moderator WillWagner's Avatar
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    Quote Originally Posted by manders View Post
    Look at 3, see in the picture how the liner is wavy and 4 is smooth? It starts just below the ring reversal area.
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  8. #35
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    Hi Will,

    As usual ... great info! I owe you a steak dinner!!!

    After you pointed it out, I do feel a slight difference between #3 and #4. I'm gonna do some more digging, I'll let you know what we find.

    Thanks.

    MAnders.

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    4 Star General snowtrac nome's Avatar
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    Mr Wagner you are a real gentleman its always nice to have a subject matter expert around to help folks out. I don't have any cummins to pick the brain of I usually use the book. but I do have a few buddys at Cat to pick up tech support when necessary. those of you that share info only received from working at a dealer are a real help to those of us who are stuck in the field working on every thing.

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  11. #37
    Moderator WillWagner's Avatar
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    Thanks, I like to help out, it is nice to see things get fixed and driving again. Talking is easier than typing, PM me and we can connect via phone if you need help. I looked, no failure analysis book for bearings/cylinders, reuse guidelines, musta gave that one to one of the guys when I left. I did find a fracture analysis book tho, I forgot about that one.
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