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Cat 235 Boom Cylinder Pin Removal

Cub · 2026-05-28 19:30

Hi Guys. Haven't been around for a while. Been busy with work, life, etc. Was using my old 235 the other day and my right boom cylinder sprung a leak. Have made arrangements to get it checked out and repacked. Simple removal, 2 hoses, 2 pins, right? Wrong. Removed the bolt in the strap on the top pin thinking I could pry it out with a bar. That's not happening. Tapped on the strap with a good sized ball peen hammer and it sounded like hitting and anvil, (Ping) not the clunk I was hoping for on something that is going to move. The outboard end of the pin is threaded, 1 1/2 (I think) fine thread, is there some tool that can be threaded in there to??? I got the idea of making something if I can find a bolt big enough to fit in there, but... Before I screw something up, has anyone else be faced with this dilemma? My Service Manual talks about Stick cylinder removal, but nothing about Boom Cylinders. Any guidance would be greatly appreciated.

Replies28
  1. #1Nige2026-05-28 21:19

    See the attached. Gird your loins, this could be fun......... The 5H9817 puller is a 50-ton double acting cylinder. The part number has been superseded by 6V3175. The 9S5558 Stud mentioned in the tooling is high-tensile BTW, not plain common-or-garden threaded bar.

  2. #2Zewnten2026-05-28 22:29

    If its not moving then a center hole hydraulic puller is your best option. Ive seen homemade slide hammers to try and move them but... The first thing I'd make sure is the boom weight is off the pin.

  3. #3HarleyHappy2026-05-29 08:49

    The way it sounds, you need to hopefully find the sweet spot, that has the least amount of pressure. After that, you can try the slide hammer but have never really had any luck with that. I have a 30 ton hollow ram that I use hardened threaded rod with an end plate and whatever stock I need to ft over the pin. I had a 50 ton but was sick of finding a way to lift it up and place it, without killing my back and someone wanted it more than me. Either way, the pins have to come out but finding that sweet spot, is the key. Good luck and stay safe.

  4. #4SlatcoAu2026-05-29 09:53

    Hopefully your removal difficulty isn't due to pin issues. I had a leaking cylinder on my 824K loader and when I pulled it I got a nice surprise inspecting the pin. Nothing $400 for a new bushing and $1000 for a pin plus bunch of "loin girding lol" couldn't fix.........

  5. #5LCA0782026-05-29 10:06

    Arrgh. I'm concerned I'll be in the same boat soon with my 325B that is starting a leak on the right boom cylinder too so I'm following you on this. But....I also wondered if instead of removing the whole cylinder, could it be possible just unpin the rod on the boom and then slide the whole rod assembly out and take that to the shop for a reseal? But yes, either way you gotta get the pin out and I don't have much help for you on that right now.

  6. #6SlatcoAu2026-05-29 10:09

    Yeah, that is what I did.

  7. #7Nige2026-05-29 11:12

    So long as there are no issues with the cylinder barrel that would be a perfectly acceptable option.

  8. #8Cub2026-05-29 18:07

    Thanks Nige. You are The Man. I wondered the same thing. Gonna have to sit back and scratch my head for a bit on this one. My homemade idea was If I could find something to thread into that pin, like a long bolt, weld it to a thick length of steel, like a tractor draw bar cut down to 1' long (1 3/4" Thick X 2 3/4 Wide) and use 2 Hydraulic Jacks to push the pin out. First thing I gotta do is get the Boom in the right position. Bleed off the pressure and see where I'm at.

  9. #9Cub2026-05-29 18:10

    Thanks. Boom is out of recommended position. Funny thing is, correct position is how I had it to begin with, then thought stretched out might be better. What do I know.

  10. #10Cub2026-05-29 18:12

    Thanks. When it's over and done I'll know how to do it. Most of what I know I learned this way.

  11. #11Cub2026-05-29 18:15

    Well, I'll let you know how the Pin comes out. Stay Tuned.

  12. #12Zewnten2026-05-29 22:52

    I've done this on field rebuilds. Works well if one can get the piston out.

  13. #13Cub2026-06-21 13:15

    Happy Fathers Day Gentlemen. Been busy on a road job last few weeks and haven't had time to play with my own toys. 235 needed batteries so I put them in and stood back and thought do I want to really get into this. Well, it's gotta be fixed so I fired the thing up and folded it up according to Nige's directions and tapped on the strap on the end of the pin. It moved! With ease. Great day in the mornin. Setting the boom down I could see the "Slop" place between pressure up or down and went looking for the sweet spot as someone mentioned earlier. Need to saw up some Hardwood Blocking to hold the boom before i get to carried away but faith has been restored. It's gonna come apart. I found this Bolt 1&1/2" Fine Thread High Tensile that will thread into the Pin and was going to make this homemade thing out of a Tractor Draw bar and a couple Bottle Jacks, and may still if needed but I think it's going to come out fairly easy. Machine was pretty well maintained and well greased, so fingers crossed. Once the pin is out I'll address it further.

  14. #14Welder Dave2026-06-21 21:29

    If it moved initially it should come out without too much trouble. You can use the mounting ear on the pin to turn it if need be.

  15. #15Cub2026-06-22 05:11

    I hope so.

  16. #16Nige2026-06-22 05:17

    To suck the guts out the cylinder should be as near horizontal as possible. Hard to tell from that photo but if you get the top pin out and then suck the rod back in a few inches to clear the upper mount will the cylinder clear the side of the bucket when you lower it to the horizontal.? If not then you may have to consider removing the bucket first. Just something to think about.

  17. #17LCA0782026-06-22 15:51

    After getting the rod horizontal and ready to pull apart, what's the best way to not make a mess of hydraulic oil when removing the rod? I'm sure there's a few tricks other than filling up a couple 5 gallon buckets??

  18. #18Nige2026-06-22 16:33

    A 55-gallon drum with the top cut off gives you a fair target to aim the oil at.

  19. #19ps66x42026-06-22 17:01

    Why wouldn't you dig a hole for the stick and bucket so you could lower the boom some more? If you could lower enough couldn't you build a platform to stand on?

  20. #20Nige2026-06-22 17:16

    Lower the boom too far and the boom cylinders could be so far retracted that you wouldn’t be able to get the top end of the rod out of the cast mount on the boom.

  21. #21ps66x42026-06-22 18:15

    I thought about that, looks to me he still has close to a foot more then he need to get it out. If he could get the bucket even with the tracks and get the pin chest high would be better. Is that pin holding both cylinders or two short pins?

  22. #22ps66x42026-06-22 18:17

    I thought about that, looks to me he still has close to a foot more then he need to get it out. If he could get the bucket even with the tracks and get the pin chest high would be better.

  23. #23Cub2026-06-23 07:15

    Maybe I'm a whimp, but I'm thinkin to just remove the cylinder and let the hydraulic shop deal with it. I haven't talked to them about taking it apart and whether they want it that way and will guarantee their work if I reassemble the cylinder on site. The man I talked to said "when you get it off, call me and we'll come get it". A little cylinder off my tractor lets say would be a different story, but this thing weighs like 900 lbs. If I had done it before, or had someone handy who had, I might be thinking Piece of Cake. I'm gonna call the hydraulic shop and see what they say first and go from there. Thanks, you guys are a wealth of knowledge for this Grasshopper.

  24. #24Nige2026-06-23 07:34

    Have you succeeded in moving the lower pin yet.?

  25. #25LCA0782026-06-23 14:59

    Oh don't get me wrong- if I could easily remove the bottom pin and just toss the whole cylinder in the bed of my truck, that's exactly what I'd do. But...we assume the bottom pin will be pretty tough without the correct pulling tools. Hopefully that pin is free like the top and it's simple for you.

  26. #26John C.2026-06-23 15:48

    Boom cylinder pins rarely freeze in the bores in my experience. Some would wear a ledge into the pin and you had to do some manipulation of the cylinder to get the pin out. Some machines had ball bushings in the boom cylinders and those were the worst. They didn't freeze in, the ball would not sit straight on the pin and they would bite into it and then wouldn't let go. Repairing big cylinders is generally not a job for part time or amateur mechanics to try unless they have the right lifting tools and some experience with other cylinders.

  27. #27Cub2026-06-23 17:59

    No Nige, not yet. But you are absolutely right, if I was to try and pull the rod out the Bucket would have to come off to get the Cylinder in a horizontal position. John. I was a Heavy Truck Mechanic for a number of years, but getting into Yellow Iron is a whole new adventure. I watched a YouTube Video on how this guy did it on a smaller Kobelco I think, so I should be good to go right?

  28. #28Cub2026-06-23 18:01

    I sure hope so. But, if not, I will figure it out.