Backhoe boom power loss

[Eagle1]

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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]

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[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.

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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.