Hello everyone this is my first post on here I have a problem with my LA402 loader. Whenever I am moving the bucket with hydraulic valve on my b7800 Kubota the bucket starts to fall down when I let go of the lever when it should hold its position. I have rebuilt the lifting cylinders and the bucket cylinders at the same time because they were all leaking, and replaced hoses because of being dry-rotted. The lifting cylinders work perfectly. I am thinking it might have something to do with the spool valves in the hydraulic lever, but I am not sure.
LA402 bucket not holding position
- Thread starter JD2021
- Start date
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
A simple way to isolate the problem is to put a small ball valve in the line coming from the rod end of the cylinder. Curl the bucket and close the valve. If it droops with the valve closed the cylinder(s) is leaking internally. If not the control valve ls leaking.
Dan
My impression was that the issue was with the loader arms, and not the bucket tilt.
Perhaps the OP could clarify?
In the meantime, I have a question that I am having trouble visualizing the answer to.
If the OP messed up one of his cylinders when rebuilding them, and it was leaking past the piston severely, would the loader drop even if the loader valve was good? Worst case it would be like replacing one of the cylinders with a hose...But the remaining cylinder volumes are different on each side of the piston...not sure how this would affect things...
Would I need to put a ball valve on both hydraulic lines for the bucket
I rebuilt all of them at the same time and had everything lubricated when reinstalling the cylinders all the seals. Not saying one didnt mess up when I inserted it. But if one of the seals I installed was bad it would cause that fluid change even if the other cylinder would be good.... No the issue is with the loader bucket the lift arm cylinders are working perfectly.
If you are going to use a ball valve, make certain it is a hydraulic rated one and not a plumbing one from Home Depot.
Exceeding rare for valve spools to be leaking unless your fluid was full of grit which not a common occurrence.
The attached testing procedure is not difficult to do and can yield a lot of info such as a swelled or bulged cylinder.
I am assuming you did not follow Kubota's recommended use of special tools to stretch and then to compress the seals.
I will attach them not to be critical but instead to broaden your knowledge. I will also attach a shortcut Messick's techs use.
Dave
Exceeding rare for valve spools to be leaking unless your fluid was full of grit which not a common occurrence.
The attached testing procedure is not difficult to do and can yield a lot of info such as a swelled or bulged cylinder.
I am assuming you did not follow Kubota's recommended use of special tools to stretch and then to compress the seals.
I will attach them not to be critical but instead to broaden your knowledge. I will also attach a shortcut Messick's techs use.
Dave
Attachments
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
When the bucket cylinder leaks internally the weight of the bucket can pull the cylinder out. The base end has a larger volume and the force of gravity pulling on the rod forces the oil past the leaking seal creating a vacuum in the base end. If you unpin the bucket the rod will partially retract on its own due to atmospheric pressure on the external end of the rod. Pull on the cylinder and it will come out. Let go it will retract. Another indicator the cylinder is bypassing.
Dan
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
You are not going to be applying any significant hydraulic pressure so the valve does not need to be high pressure. All you are using it for is to hold the unloaded bucket. I would suspet the cylinder but valves and spools do wear out.
Put it in the single line coming out of the loader valve. Probably easiest to put it on the end where it tees into two separate hoses.
Dan
Thanks to the OP for the clarification that the issue is with the bucket and not the loader arms.
My LA402 has quick connects on the loader valve.
What I would probably do, is swap them as a test. Make the loader lift function work as bucket tilt, and bucket tilt work as loader lift.
If the problem follows the change, then the issue is likely the control valve. IF the problem remains the same, the issue is likely the bucket tilt cylinders. Thinking of my loader hydraulic lines, I am not sure one could easily get any lines crossed when removing and reinstalling cylinders, so that is probably not the issue.
At least in my sometimes illogical mind...LOL
My LA402 has quick connects on the loader valve.
What I would probably do, is swap them as a test. Make the loader lift function work as bucket tilt, and bucket tilt work as loader lift.
If the problem follows the change, then the issue is likely the control valve. IF the problem remains the same, the issue is likely the bucket tilt cylinders. Thinking of my loader hydraulic lines, I am not sure one could easily get any lines crossed when removing and reinstalling cylinders, so that is probably not the issue.
At least in my sometimes illogical mind...LOL
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
If you have quick connects on the loader valve just curl the bucket and support it. Unplug the quick connects and remove the support The valve is now out of the circuit and any droop is inside the cylinder(s)
Dan
Is there an echo in the room?
Sorry, GeoHorn, I could not resist!
From post #9:
My LA402 has quick connects on the loader valve.
What I would probably do, is swap them as a test. Make the loader lift function work as bucket tilt, and bucket tilt work as loader lift.
If the problem follows the change, then...
Hope the OP reports back with an update.
LOLOL….. apparently so! (I‘ve slept since this thread began and didn’t recall the #9 post when I re-opened the discussion)..Is there an echo in the room?
Sorry, GeoHorn, I could not resist!
From post #9:
My LA402 has quick connects on the loader valve.
What I would probably do, is swap them as a test. Make the loader lift function work as bucket tilt, and bucket tilt work as loader lift.
If the problem follows the change, then...
Hope the OP reports back with an update.
Gotta wonder tho’….. if repeating the suggestion doesn’t provoke the OP to at least TRY it… then maybe it should be repeated IN LARGE BOLD!
