How to rebuild a hydraulic cylinder?
- Thread starter urednecku
- Start date
My experience was $165 for a hydraulic shop to do the first one. They told me the rod was bent and had to be straightened. I hadn't noticed a bend.
They used a huge pipe wrench to get the end cap off, leaving minor nicks.
I did the other one for under $10. (Plus $30? for the huge pipe wrench, 36" or 48", I have both). There are a couple of o-rings and seals on the piston, and also where the rod goes through the piston. You need to detach the piston from the rod before you can replace the seals in the cylinder's end cap.
The seal in the cylinder-end cap (or maybe it was the one on the inner bore of the piston?) is inside a counterbore. It needs to be folded to get it in there. I had the shop install that one for me. I've read those sometimes need to be heated to get them flexible enough to go in without damage.
I've heard the bore in the cylinder should be honed so the rubber 'piston rings' will wear in but I didn't have a suitable hone so I skipped that step.
The repairs were 3~4 years ago. Neither 'my' cylinder nor the $165 one leaks.
My advice: Try to buy or make the spanner to get the end cap off without marring it. But that's just cosmetic. A giant pipe wrench works as well. (On my elderly Yanmar a few more nicks are unnoticeable.
In that photo, the one I repaired is on the far side.)
Have the cylinder, and then the piston, attached to the tractor while you unscrew the cylinder end cap, and then the piston-to-rod nut. You need this to resist the force of the big pipe wrench.
They used a huge pipe wrench to get the end cap off, leaving minor nicks.
I did the other one for under $10. (Plus $30? for the huge pipe wrench, 36" or 48", I have both). There are a couple of o-rings and seals on the piston, and also where the rod goes through the piston. You need to detach the piston from the rod before you can replace the seals in the cylinder's end cap.
The seal in the cylinder-end cap (or maybe it was the one on the inner bore of the piston?) is inside a counterbore. It needs to be folded to get it in there. I had the shop install that one for me. I've read those sometimes need to be heated to get them flexible enough to go in without damage.
I've heard the bore in the cylinder should be honed so the rubber 'piston rings' will wear in but I didn't have a suitable hone so I skipped that step.
The repairs were 3~4 years ago. Neither 'my' cylinder nor the $165 one leaks.
My advice: Try to buy or make the spanner to get the end cap off without marring it. But that's just cosmetic. A giant pipe wrench works as well. (On my elderly Yanmar a few more nicks are unnoticeable.
In that photo, the one I repaired is on the far side.)Have the cylinder, and then the piston, attached to the tractor while you unscrew the cylinder end cap, and then the piston-to-rod nut. You need this to resist the force of the big pipe wrench.
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You'll Like This Hydraulic Info
Urednecku, You can do it!! check this out!. I thing this is a great site and it has great,clear pictures and shows how to build your own wrench to aid in breaking down the cylinder too!! . Bordercollie
http://hubpages.com/hub/Hydraulic-System-Repairs-How-to-Rebuild-or-Repair-Hydraulic-Cylinders
Urednecku, You can do it!! check this out!. I thing this is a great site and it has great,clear pictures and shows how to build your own wrench to aid in breaking down the cylinder too!! . Bordercollie
http://hubpages.com/hub/Hydraulic-System-Repairs-How-to-Rebuild-or-Repair-Hydraulic-Cylinders
urednecku
Member
Thanks, California! One cylinder is off the baler. I don't think there's room to pin it back in position then use a pipe wrench. I'll try pinning it to the trailer hitch of my pu, if I decide to try it myself. Sounds like it's fairly easy job, so depending on prices I'll probably see if I can mess it----er, I mean fix it myself. The end looks like it's been off before, there are teeth marks (pipe wrench?) on the cap.
Bordercollie, thanks for that link! There's not any holes for a spanner wrench of any kind, the rim's kinda thin, so I'm thinking (read hoping!!) maybe it's not too hard to get out.
Bordercollie, thanks for that link! There's not any holes for a spanner wrench of any kind, the rim's kinda thin, so I'm thinking (read hoping!!) maybe it's not too hard to get out.
Keep the pipe wrench down by the end of the cap.
If the cap is thin you don't want to crush its part where you need to start threads to get it back on!
But really, it was clear that my cylinders were designed for a shade-tree mechanic to maintain.
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urednecku
Member
Keep the pipe wrench down on the end of the cap.
If the cap is thin you don't want to crush its part where you need to start threads to get it back on!
By thin, I was refering to the amount of flange the teeth had to grip...but looks like the metal might be a little on the thin side, too. Thanks for the warning!
I looked at Bordercollie's link.
If your end cap looks like that Case photo with internal threads and those holes for a special wrench, then I don't think a pipe wrench can grip it. So you will need to buy or make the wrench like that article says. A couple of twist drills of the right diameter would be the right grade of steel. They could even drill their own holes through the wrench before you weld them into it.
My cylinders have caps that screw on so they were easy to turn with the pipe wrench - after I bought a monster wrench.
If your end cap looks like that Case photo with internal threads and those holes for a special wrench, then I don't think a pipe wrench can grip it. So you will need to buy or make the wrench like that article says. A couple of twist drills of the right diameter would be the right grade of steel. They could even drill their own holes through the wrench before you weld them into it.
My cylinders have caps that screw on so they were easy to turn with the pipe wrench - after I bought a monster wrench.
I don't see any way to get a grip on that.
If it were me - I would carry that in to a hydraulic shop to have them open it, and sell me the seals. Then return and let them do the final tightening.
Or have them do the entire rebuild IF their price is reasonable. In my case, I thought $150+ they charged me for labor was way unreasonable.
If it were me - I would carry that in to a hydraulic shop to have them open it, and sell me the seals. Then return and let them do the final tightening.
Or have them do the entire rebuild IF their price is reasonable. In my case, I thought $150+ they charged me for labor was way unreasonable.
Green cost $$. We once had to replace a specialized cylinder on the JD loader . It had a bent shaft and they charged close to $600. It is rather small too. I know we could have gotten one from surplus center and adapted it if we had the time to wait but our hands were tied. They obliviously saw my BIL coming. The cylinders on our JD loader have a snap ring type ring that hold it in place. I'm not sure but think I remember my Dad carefully removing the ring from the groove they sit in by using a small screwdriver type tool and hammer. He would follow the ring till the small place where the ends almost meet and work it out from there.. I should have paid more attention. I have much regret about such like that. Bordercollie
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Always wear eye protection when removing those rings as they are under pressure. Bordercollie
urednecku
Member
Thanks, guys. I'm waiting on the JD dealer to call me, but 3 other calls I made went from about $80 to $300! 
I just talked to the man I bought the machine from, he said to take the price out of what I owe him--he promised a working machine.
I can NOT ask for a better deal than that!!!
I just talked to the man I bought the machine from, he said to take the price out of what I owe him--he promised a working machine.
I can NOT ask for a better deal than that!!!
Just a guess - I wonder if the dealer uses a press and something like a oxygen sensor socket (notched one side) to press that end cap in and compress an o-ring behind it, then removes a snap ring like you described.
I've heard you pay a lot for Deere quality. Possibly this is an example, intentionally made so only dealer tools can get it apart.
Wish I would have saw this post in time. If you could have pulled the rod out a little bit, it appears you have a gland nut. I you look at the notch at approx. 12 o'clock on the rod, that's where you would put your wrench. I wold have had to see it with the rod out a bit to know for sure. Like everyone's said rebuilding them isn't that hard, getting them apart is the worst part. Sorry.
Turn the piston rod to unscrew the end cap? I'm confused.
Don't remember saying to do that. I apologize if I confused anyone on this. I was using the rod as guide. If you look at approx. 12 o'clock on the rod right at the top of the cylinder, there is a ring with a notch in it (should have a couple more notches around it). This is what I believe to be the gland nut. That is what you can unscrew, not the rod. I was basically saying that from the picture, this is what I saw. I am not an expert on all makes and models of hyd. cylinders, but I have repacked quite a few. Once again the hard part is figuring out how to get it apart (learning curve), replacing the seals (packing) isn't too bad. Usually if you can figure out how to get it apart you can get it back together.
That makes sense. That is where I would expect to find holes or notches for a special wrench.
You must have a better monitor than this laptop - I can't see a notch there.
You must have a better monitor than this laptop - I can't see a notch there.
