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Old D7. Potential trans or TC issues. Looking for someone that knows them.

Discussion in 'Dozers' started by fastline, Dec 26, 2021.

  1. fastline

    fastline Senior Member

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    This is an old E series with 339. The history would get very windy but to shorten this up, it has been sitting quite a while, only recently realized the trans cooler failed and put all the coolant in the trans. All that repaired but on test fire, engine sounded like it was laboring. I determined that the output shaft coupler from TC to trans is not spinning. Actually nothing will make it spin, and I think it is supposed to, even in neutral? i say this because there is a vid of a guy taking out a trans and he just turns the u joint like nothing.

    The machine was moved where it is by just rolling it as it should be in a neutral condition when not running. I tried to pull on it with a tractor and right now it is dead weight. At this point, I have to figure out what is at fault, and if there is any use trying to break it free. I don't know enough about these trans and TC systems to determine which and how it is hung up, but I resorted to beating on the U joint with a sledge to try to get it to pop free with no luck. I have not given the insane beating, just trying to talk nice right now.
     
  2. Nige

    Nige Senior Member

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    G..G..G..Granville.........!! Fetch your cloth.
    It is supposed to rotate freely in neutral or with the engine stopped. Even if you can't turn it by hand something like a screwdriver through the u-joint should turn it easily. Can you remove the u-joint and then try to rotate the converter output yoke and the transmission input yoke separately to see if one or other of them will turn.?
     
    .RC. likes this.
  3. fastline

    fastline Senior Member

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    It might come to decoupling the yoke today but I have given this a little thought and here is my theory. The trans has not tried to shift in a long time. What I suspect is I activated one or more clutch packs and they are not returning, thus locking the trans into one or more gears. Correct me, but I think the clutch packs engage with trans pressure through a clutch pack piston. When pressure is removed, the piston should return via the compression return springs. I suspect that is not happening.
     
  4. fastline

    fastline Senior Member

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    At this point, I would just ask if anyone would be willing to check SIS for any relevant data on hydro schematics, or possibly flow diagrams. I have pressures acting super odd, and a lot of different things going on to know where next to go. I found plugged pressure side filters, and even one partially collapsed, but all I have found is snot, no metal fragments in pressure filters that I can see at all. All is just super frustrating but I really want to see hydro pressures looking right before I go disconnecting anything.

    There are a couple of check and relief valves in the system, but I have no idea where they are, their function in the system, etc.
     
  5. 1693TA

    1693TA Senior Member

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    Snot. Does the tractor use an engine coolant supplied oil cooler? If so, what kind of condition is the engine coolant in? Any slime in there? No experience with Caterpillar at all so no offer of advice but I've seen older tractors with engine problems basically have water and additives added to the cooling system to keep it going while it leaks into the transmission through the cooler. The major problems rear their ugly head when something is lubricated by these improper additives until something seizes much as you are experiencing.

    Again no idea myself and just relaying a scenario I've seen in other equipment.
     
  6. fastline

    fastline Senior Member

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    This system is being recovered after a trans cooler failure that put large amounts of coolant in the trans. There is no guessing about that at all. Right now it is about determining the full extend of damage and see if it can become mobile again without a full tear down.

    I realize snot will form when water and oil mix, but it had time to separate and we got most of the water out. Due to the expense of oils, it was decided to see if we can just get the machine moving again before doing a 30gal oil change.
     
  7. 1693TA

    1693TA Senior Member

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    I was hoping that wasn't the case as it gets to a lot of $$$ to make a repair once something seizes from lack of lubrication. Ethylene glycol is an excellent coolant, but a terrible lubricant. As it warms it actually gains "stiction", (less lubricity) which is very hard on parts requiring constant lubrication.
     
  8. Bluox

    Bluox Senior Member

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    You know most Cat experts on here have to have a serial number .to look info up.
    Is yours a secret or shall everyone just guess what it might be. ?
    Bob
     
    bccat likes this.
  9. Dave Neubert

    Dave Neubert Senior Member

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    Sounds like a bearing is seized up I'm betting in the tranny because motor will run with out drive turning probably will need to go through both though