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Komatsu hydraulic cylinder repair

Discussion in 'Dozers' started by Don Shilling, May 23, 2020.

  1. Don Shilling

    Don Shilling Well-Known Member

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    I've just had the occasion to repair a leak on the blade tilt cylinder on my D21. I bought a seal kit and proper size hook spanner. However, the design of the slots on the cylinder end cap was such that the wrench would slip out of the slot because of the taper bottom of the slots. I stopped before I caused any damage and took the cylinder to a professional shop and let them replace the seals.
    I was wondering if there is a special design spanner wrench for these Komatsu cylinders?
     
  2. John C.

    John C. Senior Member

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    Big pipe wrench or a chain wrench is all I ever used on them.
     
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  3. mitch504

    mitch504 Senior Member

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    Yep, 48" pipe wrench does wonders
     
  4. JD955SC

    JD955SC Senior Member

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    Those caps are usually too tight for the hook spanner to do anything.

    Air hammer and flat bit will often move them, pipe wrench, chain wrench (aggravating) are other options. While putting tension on them with the wrench smack the hell out of the area just behind the cap with a hammer...this is the area where the gland assy is threaded into the barrel. If that fails then you have to heat them. Also always check for setscrews.
     
  5. Krackerjack9

    Krackerjack9 Well-Known Member

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    I had the same issue with mine as the other post stated I used a 36in pipe wrench and made sure it was good and snugand used a sledge to hit on the back side of wrench up close , you could put a cheater pipe on the end of pipe wrench but what happens is that those cylinders are made of aluminum and will start gouging pretty good before it breaks loose, I did all mine about a month ago, the smaller cylinders they make a tool to put the inner seal in and its worth getting about $30.00 and you get alll 3 sizes. I made a post on this on my section in the komatsu d20 d21s, just make sure you load that head up with grease this way the seal wont ride up when your putting it back together, don't be surprised if you run across some water in there that's the lowest part so water might be in there maybe 3 or 4oz at the most
     
  6. Krackerjack9

    Krackerjack9 Well-Known Member

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    once you hit the pipe wrench 2 or 3 times then try tugging with your hands all it takes is for it break loose a 1/4in and after that its comeing off oh going to be a good amount of oil coming out so I would raise blade then put some blocks undneath to hold it up then a bucket or big catch pan and you don't have to take the whole thing off just that one pin leave the other one attached there is also some rubber gromets or isolators not sure the correct name mine were in really good shape, need anything else shoot me a message have a great weekend
     
  7. Welder Dave

    Welder Dave Senior Member

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    What hyd. cylinders are aluminum?
     
  8. mikebramel

    mikebramel Senior Member

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    Heads.... not the tube
     
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  9. Welder Dave

    Welder Dave Senior Member

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    What's the advantage of an aluminum head on a steel cylinder?
     
  10. Delmer

    Delmer Senior Member

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    Cheaper, easier to machine.
     
  11. Krackerjack9

    Krackerjack9 Well-Known Member

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    well im not 100& sure but on the Komatsu d20 their aluminum the heads are
     
  12. Welder Dave

    Welder Dave Senior Member

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    On a dozer it doesn't make sense to me. Steel isn't hard to machine and should be cheaper than aluminum.
     
  13. .RC.

    .RC. Well-Known Member

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    You get to sell a whole new ram when the aluminium head cold welds itself to the steel barrel.
     
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  14. Welder Dave

    Welder Dave Senior Member

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    I was thinking about galvanic corrosion.
     
  15. Delmer

    Delmer Senior Member

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    Corrosion may play a part in the welding. Aluminum just doesn't like to be threaded like that, seems like steel bolts in cast aluminum is OK, but threaded alloy parts just like to gall and seize.

    I guess you're right about aluminum being more expensive than steel, but I still say the aluminum has to be much cheaper to machine, why else would they use it?
     
  16. Welder Dave

    Welder Dave Senior Member

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    Would be interesting to know.
     
  17. John C.

    John C. Senior Member

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    Cylinders are bought on bid by local contractors usually. Low bid gets to use whatever material they see fit.
     
  18. mikebramel

    mikebramel Senior Member

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    Aluminum can be used as a direct bearing surface
     
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  19. Welder Dave

    Welder Dave Senior Member

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    I guess it would save having to need a wear ring.
     
  20. Don Shilling

    Don Shilling Well-Known Member

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    I took my cylinder to a local shop where they had the proper tools to remove the end cap. The end result was no damage and a professional job overall. There is never a substitute for the proper tools for a professional job!