Backhoe boom power loss

[mattphillips18]

I recently purchased my first tractor, a used LS xj2025h with 1104 backhoe installed. I used the hoe a couple times, and the last time noted the boom floating down in a few seconds. Soon I couldn’t get the bucket to penetrate the ground and the boom would barely come back up. Now the boom is up, Keeper” is Goldie up, and I can’t pull back the boom enough to take off the “keeper”. It seems like the other moving parts are working properly, though I haven’t tested under load. Just the boom was super slow and under powered. I checked hydraulic fluid level and it’s at the max, fluid is clean and clear. Any guesses?

 

[ptsg]

Sounds like bad piston cylinders on that cylinder that lifts the boom. Time to pull it apart and inspect.

 

[mattphillips18]

I’m new to hydraulics, I don’t see any leakage, what would I be looking for? Thanks for the attention.

 

[ptsg]

The piston seals are inside the barrel of the cylinder, so it's not an external leak. You can't really see it from the outside unless it was leaking from the rod seal.

It may be a good idea to watch some videos about rebuilding hydraulic cylinders so you get a better idea on what's going on.

 

[mattphillips18]

Thanks, good idea.

 

[Eagle1]

You may just have a linkage problem in the joystick. The valves us a rod and bearing to translate the joystick movement to the valve. The bearing can go bad quite quickly if water get to them. I've seen the bearing come out completely. I converted mine to industrial heim joints since LS does not sell the piece parts. All under the boot.

 

[Eagle1]

This thread may help
BH Joystick Issue

 

[rScotty]

My Kubota did something similar with its boom cylinder... it began after a few years when it could not retract the boom cylinder enough to latch the boom lock.

So...I agree with the previous opinions - the problem with yours could be either the joystick not sending pressurized fluid to the boom cylinder, or it could be that the boom cylinder is getting pressurized fluid, but not able to use it to move the boom cylnder becauxe of an internal problem with the boom piston. Or something else, but those are the ways to bet.

You need to decide which problem you are dealing with. The joystick is easy, sometimes just a matter of some lube. Look it over first. Problems there are pretty obvious. If not sure, the easiest next step would be to insert a a hydraulic "T" fitting in the line that extends the boom cylinder and measure the pressure. It can stay there permanently. I use a 5000 psi gauge with the T. Together they cost about $50. Or you can buy a hydraulic test kit from Amazon that has all the quick change adapters and gauges for about the same price. That's probably how to go.
Your dealer may not be much help. Hydraulics seem to mystify many tractor mechanics. Neither of the two local dealers here has even the most basic hydraulc test tools.

BTW, on mine the problem was the nut holding the piston to the cylinder rod was not attached properly and came loose from the boom cylinder rod. It was a known factory problem and fixed under a replacement boom cylinder recall. I didn't have to do a thing.

rScotty

 

[mattphillips18]

 

[mattphillips18]

This is the boom control. Things seem to feel fine, control springs back, parts all seem there, corrosion at a minimum. I did notice when I pushed forward as if to lower the boom, there was a decent sharp reaction from the piston. But when the control is pulled back, that’s a very soft, slow reaction. Still not enough power to let the boom down so take that for what it’s worth.
Thanks for the valuable insights.

 

[Eagle1]

View attachment 3285321

Looks clean and tidy in there. Mine (bought used) was a mess and sloppy. Had to hold your mouth right for some of the functions to work.
New joints now she is good and tight.
If the two valves a controlled nicely by each joy stick you into the harder stuff of lines and seals.

 

[mattphillips18]

View attachment IMG_0145.jpeg

 

[mattphillips18]

This detention cap (silver thing) seems to be solid, though if I put my fingers on it I come away with hydraulic fluid. No mess, just wet. Is that normal or a possible problem?

 

[Eagle1]

After time it seems that all hydro system weep a bit, should not but reality says they do. That cap on the boom valve contains your detente for the boom float position. Sometimes things get crusty in there but you would notice it sticking or not going into float.
If you do pull be careful there are springs and little bearing balls for the detente that will try to escape, slowly or mighty quick sometimes.

 

[mattphillips18]

I’ll leave that alone for now. I found wear on both hoses for that cylinder, through the rubber and exposing the braid. I didn’t see any leak or bulge when activated, but need to replace. Leaning towards cylinder issue, gotta watch some YouTube.

 

[rScotty]

I’ll leave that alone for now. I found wear on both hoses for that cylinder, through the rubber and exposing the braid. I didn’t see any leak or bulge when activated, but need to replace. Leaning towards cylinder issue, gotta watch some YouTube.

Control valve assemblies for backhoes are a lot more complicated than loader controls. BHs have check valves - which some loaders lack. And instead of just a single relief valve, it isn't unusual for BH controls to have a separate relief valve for each motion. These are common BH problem areas.

Any of these check or relief valves could have a piece of crud caught in the valve face holding it open. Holding a relief or check valve open would cause exactly the same symptoms as a bad seal on a cylinder piston.

The illustration in message #6 shows a BH control assembly with three check valves and four relief valves. I don't know about yours, but for Kubota it is typical for these valves to be dissassembled for cleaning. You can search for articles on it here on TBN.
rScotty

 

[nwa]

Control valve assemblies for backhoes are a lot more complicated than loader controls. BHs have check valves - which some loaders lack. And instead of just a single relief valve, it isn't unusual for BH controls to have a separate relief valve for each motion. These are common BH problem areas.

Any of these check or relief valves could have a piece of crud caught in the valve face holding it open. Holding a relief or check valve open would cause exactly the same symptoms as a bad seal on a cylinder piston.

The illustration in message #6 shows a BH control assembly with three check valves and four relief valves. I don't know about yours, but for Kubota it is typical for these valves to be dissassembled for cleaning. You can search for articles on it here on TBN.
rScotty

I would suggest checking the control valve assembly as well. I had a similar sounding situation on a fairly new Kubota. Took all the weight off the affected cylinder, removed the hose from the control valve, bled a little fluid out, and reinstalled the hose. Must have had a piece of something in there that came out as I haven't had it happen again. You could also switch it around with another hose at the control valve and see if it works off a different port. If so, then it's not the cylinder.

 

[Gord Baker]

You may just have a linkage problem in the joystick. The valves us a rod and bearing to translate the joystick movement to the valve. The bearing can go bad quite quickly if water get to them. I've seen the bearing come out completely. I converted mine to industrial heim joints since LS does not sell the piece parts. All under the boot.

View attachment 3281492

YIKES!

 

[Bentrim]

You said the boom leaks down in a few seconds. That sounds as if the piston packings are bad. Take a piece of pipe steel or pvc etc. Or even a solid bar and raise the boom as it falls put the pipe against the cylinder barrel, listen for a hissing sound as oil bypassing the piston.
As for the valve does moving it slightly change the speed or stop the drop?

 

[mattphillips18]

I can’t even get it up enough to unseat the “keeper”, which secures it in the up position when not in use.
Hmmm, I’ll try switching hoses, sounds easy and logical to me.