LB 400 pistons repair

[rogerwrob]

I have a friend that has a older Kubota. It has a LB 400 FEL on it . He is trying to replace the seals in the pistons and it sounds like its a costly adventure. the Pistons are $400 -$500. He Bought a seal kit for 40 bucks and that did not go good. What is the cheapest route to go ? can they be replaced by a after market piston? Thanks Roger

 

[oldnslo]

Are the pistons or cylinder bores scored or damaged in some way? If yes then those surfaces need to be smoothed out or replaced for the seals to last.

 

[rogerwrob]

No, pistons are not damaged.

 

[oldnslo]

If pistons are not damaged and cylinder bores are not scored then replacing seals should put them back in working condition.

What is problem you are experiencing?

 

[rogerwrob]

If pistons are not damaged and cylinder bores are not scored then replacing seals should put them back in working condition.

What is problem you are experiencing?

He has tried to replace the seals in the piston. It cost him 40 bucks for one seal kit . He installed the kit but still has the same problem. He said there was one washer that needed to be heated up before installing it. hes not 100% sure he did it correct. What i am trying to find out is if there is a after market piston that will fit on this Kubota FEL . 4 or 5 hundred for one piston seems pretty costly. Are Kubota pistons special in any way that you have to use just Kubota parts? If the pistons are hard to rebuild would he be better off to send them off to a place that does this on a daily bases? I have never rebuilt one so I am clueless

 

[oldnslo]

Not sure on if pistons are special but typically cylinders are not difficult to reseal but yes some of the seals can be a challenge to install.
Back to question of what is the problem with cylinder or why do you believe cylinder is failing? Are you 110% certain the cylinder is the problem and not another component in the circuit?

 

[rogerwrob]

I just got a text back from him. I asked again what the problem was and he said it is leaking internally. That sounds like seals to me. Im still looking for some Kubota owners that know where to get some replacement complete pistons. It looks like you have a John Deerr. when I was at his house yesterday he showed me the piston and that on one end it looks like a normal piston you put a pin through. The other end was special in a way. Im not sure if JD has special pistons on their tractors for FEL and so.

 

[rogerwrob]

Does this help ? Just got a text that says "its a PTFE Teflon you have to heat up , install it and put it under compression.and cool it down." is that a hard install ?

 

[oldnslo]

That is normal procedure for PTFE and care must be taken to not overstretch the material during installation.

 

[rogerwrob]

Thanks for helping out to start off. He admitted that he is not sure he did that part correct. At $40 a repair kit that can get costly. Is there a good video you know of on how to do the reseal? for the heating and stuff ?

 

[Harry in Ky]

Installing those piston seals isn't all that difficult. I have replaced a few hundred of them without problems. In fact I just did two yesterday on a Kubota loader bucket and tilt cylinder. I don't heat them unless it's colder than 40 degrees ambient. I put the O ring on the piston, then carefully stretch the seal onto the piston and into the groove. Wrap it with a length of emery cloth turned abrasive side out and tighten a hose clamp around that. Let it sit like that while I assemble the shaft seal, wiper, and O rings in the gland nut. Assemble that onto the rod and then install the piston and the nut, leaving the hose clamp in place until I'm ready to put it all back into the barrel. Whether it's twenty minutes or three day, I've never had any problems with that method.

I think your friend may have more problems than just how to install seals, but somehow I don't expect a defective piston is part of it, or it would be pretty evident.

 

[rogerwrob]

Thanks Harry . I will give this to my friend and he can maybe give it a try again. Is there a part number for the PTFE Teflon seal that he can get just that seal? I thank you for your help.

 

[mrmikey]

This method maybe help at all:

 

[rogerwrob]

Thanks . thats a nice little trick there

 

[Harry in Ky]

Kubota parts website lists an LB400 as a basic loader with fairly standard looking lift and bucket cylinders. I see nothing unusual about those pistons that makes any sense concerning your description of those your friend is working on. No pins involved, just a single nut holding the piton onto the rod. Very similar to the ones I've recently been working on.

As for part numbers they only list the number for the kit, nothing individual. A good hydraulic shop will be able to supply the individual seals needed. That' where I get mine. These were 2.5" bore, 1.25" shaft. I got seals, wipers, and O rings for three cylinders under $20 each set. I rarely order seal "kits", too many variables, different cylinder part numbers, or else kits come with parts for multiple cylinder styles, just more trouble (and expense) than it's worth. I find it's more effective and less expensive to take it apart and match the individual parts I need.

 

[Carl_NH]

Harry - that's what I do - our local Hyd shop rebuilt 2 of my B21 cylinders $100 each for labor and $40 for the kit. I have some of the tools, and knowhow, but the gland nut tool is a $40. I figure $280 of seals and labor for over 20 years of use is the cost of maintaining the machine. The rebuilt have never leaked a drop and if there is any scoring or bent rods they will fix or straighten them if needed. (more $ but that hasn't been the case so far).

 

[rogerwrob]

Kubota parts website lists an LB400 as a basic loader with fairly standard looking lift and bucket cylinders. I see nothing unusual about those pistons that makes any sense concerning your description of those your friend is working on. No pins involved, just a single nut holding the piton onto the rod. Very similar to the ones I've recently been working on.

As for part numbers they only list the number for the kit, nothing individual. A good hydraulic shop will be able to supply the individual seals needed. That' where I get mine. These were 2.5" bore, 1.25" shaft. I got seals, wipers, and O rings for three cylinders under $20 each set. I rarely order seal "kits", too many variables, different cylinder part numbers, or else kits come with parts for multiple cylinder styles, just more trouble (and expense) than it's worth. I find it's more effective and less expensive to take it apart and match the individual parts I need.

Thanks Harry

 

[kneedeep]

Take the cylinders to a Hydraulic Shop.
Some things aren’t worth the effort and cost to do in-house.
Rebuilding cylinders or gearboxes is one of those.
3510 is at dealer to get backhoe boom cylinder out and rebuild,
Way too much for me to tackle.