LK3054xs Backhoe KB2376 valve body problem looking for thoughts (2024)

I have a KB2375 on my CK30hst. The only thing that centers the valve, or actually centers the spool in the valve block, is a spring attached to the bottom of the spool that protrudes beyond the bottom of the valve block inside the approximately 1 1/2 " x 1" cup which is attached to the bottom of the valve block. The spring either compresses against the valve block when the spool is lifted or is compressed against the cup when the spool is pushed down causing the spool to want to return to a neutral position. This design is very similar to the springs on the ends of the spools in the loader valve block. Members, including myself, have had moisture enter the cup of the loader valve making it stick or hard to move. I would remove the cup from the bottom of the respective valve block and check for corrosion, possibly a broken spring, or a broken screw at the end of the spool that secures the spring in position.

Joel; why not switch your power beyond line back to the tank and disable the hoe till you have time to play with it. Seems easier than dropping the hoe and having to go through the hassle of re-attaching the hoe later. This assuming you still have the boom locking pin?

OK, so I pulled apart the backhoe valve body, for what seems like the 100th time.
I noticed before I removed from the tractor that I had oil coming out of the dipper stick control valve lower cups.
I pulled the cups off the bottom of the dipper stick control valve. Nothing looked wrong, I replaced the black o-ring just to be safe ($8 a pop for an o-ring, nutty, there's got to be an equivalent out there somewhere). I put back together and then installed back into tractor.
Still same problem, after a couple of minutes of the tractor running the dipper stick control valve starts to move itself into the up position and the hydraulics are under load.
I don't understand why this would happen? Are there any seals within the valve body or are there only the 0-rings and dust seals at either end and internally is up to close tolerances between the double acting spool and the valve body?
I'm stumped?
Thanks,
Joel

Other than those black rubber o-rings and white nylon backup washers at each end of the spool, no other seals within the block. As you said, just very close tolerances between the bore of the block and the spool. The problem I had when new was if I would just start to move the level ever so slightly to lower a stab a little more, it would let off pressure allowing the stab to move up. There was a problem/warpage in the chambers of the cast valve block that didn't allow the spool grooves to line up properly with valve chambers. New block with the old spool and related parts and all was fine. Yours was working ok from the start so something must have warn or is sticking to make it fail. I would think the spool and valve block are good. Another thing that I can think of is the valve blocks each have check valves. I assumed these check valves just held the fluid pressure/cylinder rod position when the spool is centered. Lastly is port relief valves and I'm not really sure how they work or what they actually do. I can't think of anything else because that's all the parts that are there in this simple design of a valve. Maybe give Bob, parts person, a call at Michigan Iron and Equipment. He's very knowledgeable. This should be a link to your valve block assy. Error

As there are only seals at either end of spool I am wondering if something may be stuck within the spool? I will remove spool and see what I find
Curious problem
Joel

There is something redirecting fluid pressure and forcing the spool to move. The valve block is cast and has several chambers. You'll see the chamber dividers when you look into the valve block with the spool removed. The spool is just a round shaft with grooves cut into it at various designed positions along the shaft that relate to the chambers in the block. As the spool goes up and down, those grooves allow fluid to be redirected to the various chambers which controls which of the two attached hoses gets pressure and which one acts as a return. Otherwise, when the spool is centered, it's an open center valve allowing fluid to flow through the valve and not to the hoses. Maybe it's one of the two relief valves on the block that is stuck and putting fluid pressure on the spool. A small piece of dirt or maybe a piece from a damaged o-ring is clogging it up. You mentioned fluid leaking out of the dipper stick control valve lower cup. There should be none and that cup isn't made to hold 2000psi pressure. Also, the o-ring is for seepage not full pressure. For some reason pressure is building in that valve block that shouldn't be which maybe a relief valve is stuck. Sorry I don't have the answer for you. Never had that problem but I think after disassembling that valve block and a good cleaning, you'll find the problem. One other way to possibly diagnose the relief valves is to change them from the dipper block, one at a time, with another good block and see if the problem moves to that valve block.