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CAT hydro cylinder fail after a very short time......?
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The cylinder is repaired and in my truck. My mention of the drifting the cylinder had after rebuild was ignored and only the head(rod) seal and wiper was replaced. I paid $65 for a new head seal.... I have what I am told to be my old head seal and they say it was too soft and was not a loaded Ucup design. However, they still did not install a loaded cup ,they just stuffed "one of theirs" in it. They indicate my Ucup was missing the Oring, but the guy mentioned it could have been missed and not installed. personally, I've done enough Ucups that I don't believe it was designed for one. I will probably call a hydro engineer I know to discuss so I can sleep easier. Generally I like to compare new to old. Guy was baffled that I still have my old crusty seals from that cylinder and it's because of stuff like this.
The old seal appears mint and I am probably more frustrated that I am relying on someone else and I am not use to doing that. I do agree that running a loaded Ucup is primarily to prevent leakage with lower pressures when shut down.. I will agree that it started puking after sitting for a few weeks. Not acceptable but plausible issue.
Nothing was said about the wiper. They replaced it and that was that. All I know is the guying doing the work was high enough I could get high just standing by him. I think he tried and I guess now we just put it back to work and see what happens. Still not all that happy with the drift issue, but it is certainly within CAT spec. I went backwards on that for some reason.
I will certainly use this experience to motivate me to build a hydro table.
The old seal appears mint and I am probably more frustrated that I am relying on someone else and I am not use to doing that. I do agree that running a loaded Ucup is primarily to prevent leakage with lower pressures when shut down.. I will agree that it started puking after sitting for a few weeks. Not acceptable but plausible issue.
Nothing was said about the wiper. They replaced it and that was that. All I know is the guying doing the work was high enough I could get high just standing by him. I think he tried and I guess now we just put it back to work and see what happens. Still not all that happy with the drift issue, but it is certainly within CAT spec. I went backwards on that for some reason.
I will certainly use this experience to motivate me to build a hydro table.
crane operator
Senior Member
I'm just curious why you've mentioned building a hydro bench numerous times, and what you think it has to do with fixing your cylinder?
You don't have to have a bench to repair cylinders (its easier, but not necessary), if you don't like the shop that's doing your work, take it somewhere else or do it yourself. If you don't like the seals they are giving you, order your own or call the Cat man. Its just a cylinder and seals, I'm not sure what you need a hydro engineer for.
Nige posted the diagram of where the seals go. You've got all the info, get a seal kit, and if you don't trust the hydro shop, get after it. The year is almost over, less talky more worky.
You don't have to have a bench to repair cylinders (its easier, but not necessary), if you don't like the shop that's doing your work, take it somewhere else or do it yourself. If you don't like the seals they are giving you, order your own or call the Cat man. Its just a cylinder and seals, I'm not sure what you need a hydro engineer for.
Nige posted the diagram of where the seals go. You've got all the info, get a seal kit, and if you don't trust the hydro shop, get after it. The year is almost over, less talky more worky.
Welder Dave
Senior Member
Unless you have multiple machines and dozens of cylinders it doesn't make sense to build a cylinder bench. The biggest reason for a cylinder bench is for the piston nut/bolt. You can always disassemble the cylinder and just pay a shop with a cylinder bench to loosen the nut and then tighten it after you've changed the seals.
Machine back together.. Just have to see how she does. Not leaking yet though....lol
As for the "hydro bench", I am not really looking to go nuts with a true 'pro' setup, but an aid to both break the rod nut, and have hydraulic assist for manipulating the components. Even moving at snail speed, it would be faster than having to haul a cylinder in and wait for work to be done. Because of our full manufacturing facility, I don't think this is too far outside our wheelhouse and I figure I could just throw the thing outside until needed.
We have several hydraulic power units just sitting around as well as other goods. I figure we can help some friends out on a favor network.
As for frequency, it seems like every time I turn around, something is leaking! Our farm equipment, industrial, construction, etc. And of course every single thing I buy needs hydro work. Just did both tilt cylinders in our Yale 9K fork. As I look around at the fleet, I'v had to rebuild pretty much everything.
As for the "hydro bench", I am not really looking to go nuts with a true 'pro' setup, but an aid to both break the rod nut, and have hydraulic assist for manipulating the components. Even moving at snail speed, it would be faster than having to haul a cylinder in and wait for work to be done. Because of our full manufacturing facility, I don't think this is too far outside our wheelhouse and I figure I could just throw the thing outside until needed.
We have several hydraulic power units just sitting around as well as other goods. I figure we can help some friends out on a favor network.
As for frequency, it seems like every time I turn around, something is leaking! Our farm equipment, industrial, construction, etc. And of course every single thing I buy needs hydro work. Just did both tilt cylinders in our Yale 9K fork. As I look around at the fleet, I'v had to rebuild pretty much everything.
Welder Dave
Senior Member
I would never leave important tools outside to face the elements. Even under a tarp you still get condensation and rust.
Thats western Oklahoma red dirt