JCB crowd cylinder rebuild (?)

[Richard]

Was squirting some oil out the top (ram) end of my cylinder. Of all cylinders, this one was replaced second to last....(meaning it wasn't the most recent but second most recent... 7-8 years ago) done by the dealer, paid the most for it....and it's leaking!

Anyway, took it to a hydraulic shop, they've had it for three weeks still trying to ascertain an estimate for me.

Finally, I said "nah....just cancel it and return it to me, I'm going to do something else"

Well....something else is attempt to do it myself! I've never done a cylinder. It can't be too complicated.

I don't know if I've got a wrench large enough to unscrew the cap. I'm thinking I'll try my (large) pipe wrench and most likely, a cheater bar.

Once I get it off, I can chain the end to the backhoe, use my mower, or one of two other tractors to pull apart if need be (will attempt to pull by hand to see if I can)


The unit operates FINE. The issue is a pinhole leak at the very top so under pressure, you get a fine stream shooting out. Ostensibly, all I NEED to fix are the seals on the cap.

That said... since I will have it apart, would you go ahead & just replace all the seals? (can you buy ONLY the end seal or do they all come in kits?)

I've looked up JCB gaskets on Ebay. I'm guessing they're after market. Would you be good with that or just pay a bit more and get some through the dealer? (this is where I'm leaning, this way I know I've got the right stuff)

Any special tools other than large wrench at the end? From the diagrams I've seen, it doesn't look like it.

Appreciate any thoughts.

 

[oldnslo]

Other items to consider:
Is the rod scored causing the seal to fail? If yes who will repair or replace the rod?

Is the clevis or eyelet screwed onto the end of the rod or welded? Reason for asking is if welded you will have to remove the piston from the rod to access the rod seal. This will require a large wrench and some torque.

Reassembly: will require some method of compressing the piston seals to get them into the bore.

Do you have the tools to align and push the rod/piston assembly into the bore?

May be more concerns also

 

[Richard]

Other items to consider:
Is the rod scored causing the seal to fail? If yes who will repair or replace the rod?

Is the clevis or eyelet screwed onto the end of the rod or welded? Reason for asking is if welded you will have to remove the piston from the rod to access the rod seal. This will require a large wrench and some torque.

Reassembly: will require some method of compressing the piston seals to get them into the bore.

Do you have the tools to align and push the rod/piston assembly into the bore?

May be more concerns also

On looking at the rod as it goes in/out, there aren't any obvious score marks.... then again, I don't know how subtle they can be before they matter (what to me might be a small scratch, could be a gouge in the world of cylinders)

Is the clevis screwed or welded... (pardon my ignorance on the names of parts) If you mean the part on the end where the pin that attaches it to the machine goes through, that is welded as best I can surmise (never specifically looked, don't know if I could tell without taking things apart)

Compressions if seals... hmmm.... well, I have an auto, oil canister wrench... more accurately, I have one that I use on my (hydraulic) mower and it's probably 50% LARGER than the standard auto wrenches.... would something like that work? (presuming it's large enough)

Tools to align.... well... no. I have my arms, my wits... Once it's in, I can rotate the rod to align things but that's different than lining them up for insertion. I can probably push the assembly into the bore with some straps, come-along...

This is why I'm asking (thanks for these ideas). Looking at the schematic I found, it might not be for my exact cylinder, but it looks like you "simply" unscrew the end, pull rod/piston out. Further, it SEEMED as though there was an assembly that held the piston on verses being welded (might not have interpreted it correctly)

Bottom line, it looks like it's mainly grunt and some finesse to align to reinsert. Once apart, it appears general hand tools will get the parts replaced (but I'm not sure that's really the case which is why I'm asking)

The reality is, the only place it seems to be leaking is the outer seal at the cap. Almost like they might have nicked it on reassembly and it's finally broken through.

 

[oldnslo]

Richard
By leaking at outer seal of cap do you mean where the cap screws into the barrel?

If yes then the rod being scored should not be concern since I made the presumption that it was leaking around the rod.

You are correct in that it is a fair amount of common sense and sweat equity.

Not sure on the oil canister wrench. The compression tool will most likely have to fit down inside of the barrel past the threads.

I have used a piece of shim stock and Hose clamps for compressing seals. Not pretty but it worked
I get the impression you will figure something out once you get it apart

 

[wdchyd]

Richard, after it’s apart use your fingernails and not your eyes to check if any nicks in the chrome rod are too much. Any places your fingernails snag will directly effect your rod seals. There are ways to weld, grind and polish nicks or replace the rod.

Oh and BTW, look under the wear bands on the piston for a lock pin, If there’s one don’t try to unscrew the piston till it’s out.....:2cents:

 

[wdchyd]

The reality is, the only place it seems to be leaking is the outer seal at the cap. Almost like they might have nicked it on reassembly and it's finally broken through.

After apart and the oring area at the gland is exposed, polish the oring area and check for corrosion on the cyl barrel and on the gland groove, too much and the oring will fail early.

 

[countrybumpkin]

I buy all my cylinder seals from here

https://herculesus.com

They offer kits for a lot of cylinders or individual seals of just about any type and material.

 

[Richard]

Richard
By leaking at outer seal of cap do you mean where the cap screws into the barrel?

Yes, this is what I mean. It's almost as though the cylinder was rebuilt (which it was a number of years ago) and someone took an ice pick or something thin and stabbed it through the end of where the cap screws in. It's almost like a child's squirt gun.... (heavier stream though) but the oil just "shoots" straight out in a pinhole type fashion. It only does so when pressure is on that side of course but, when you're using the machine (hoe) you are putting pressure there often so it goes from a droopy squirt to a straight squirt when under higher pressure. It's not a gush of oil but it needs to be fixed.

I've been looking for the parts (thanks for the link) on ebay and am presuming they are probably chinese made (but I don't know that). I've been debating to simply go to the dealer knowing I'd pay a bit more but, I can give them the serial number and know I've got the correct parts.

 

[Richard]

I buy all my cylinder seals from here

https://herculesus.com

They offer kits for a lot of cylinders or individual seals of just about any type and material.

I've gone there (thank you for the link)

Here's the page I found: https://herculesus.com/pages.php?pageid=56#

I need the middle cylinder on my hoe. So, it's not the bucket and it's not the boom. I've always thought it was called the crowd cylinder but it looks like they call it the dipperstick.

Fine.

They have TWO versions. How do I decide which one is correct? Everything seems the same but the cylinder column. There are two different numbers in there (suggesting there might have been two different cylinders used at which point, I have no clue)

 

[countrybumpkin]

I would pull yours apart and get measurements then contact them, or you might try contacting them first and have the serial number ready they may be able to determine that way.