B2650 FEL lift issue

[Little Kioti]

Hey guys, I’m having an issue and would greatly appreciate any help or advice.

specs: 2017 Kubota B2650HST with LA534 loader. 632 hours.

shortened version: If you lower the boom until it’s under pressure (hitting the ground), the FEL won’t lift.

The problem is with the Boom lift function of the loader. Every single other function works 100% of the time (drop, curl, dump) every time. The lift function will work 100% of the time as long as you don’t “bind” it by letting the bucket hit the ground or some form of resistance while dropping. Once there is force applied while going in the down direction, it locks up and won’t lift. It however can continue to go down forcefully even lifting the tractor off the ground. The float won’t work to break it free (even with the wheels in the air). The only thing that works to allow it to lift again is if you lower the idle and every so slightly attempt to lift or jiggle the drop/lift and easily apply LIFT. Or cut the loader off, crack the lift cylinder returns, release the pressure, start it back up, and lift. It doesn’t necessarily happen when the cylinder is all the way in the closed location either. If you tilt the bucket all the way upside down and then hit the dirt (with 2-3” of the piston exposed) it will still lock up and not go up. To free it, I can curl the bucket up (dropping the tires back on the ground and free the resistance), I can again ever so slightly apply lift and it will begin working normal. It can go up and down 100x without issue so long as it doesn’t hit the ground or some form of pressure applied downwards. The pump is most certainly attempting to lift, but it’s like it’s jammed.

My assumption is something in the loader control valve. Please help me narrow it down. I’ve read it could be the quick connects, but doesn’t make sense if the problem can be duplicated only when the loader drops and hits resistance.



Thank you for any input!!!

 

[oldnslo]

My suspicion is that you have quick disconnect starting to fail since they can act like a orifice or check preventing cylinder movement. The challenge is figuring out which one.

 

[Roadworthy]

Try disconnecting and reconnecting the quick disconnects as a starting point.

 

[rScotty]

I do not see how it could be the loader valve. To me it sounds like one or more of the quick disconnects in the hoses to the boom lift cylinders is going bad. My guess would be a broken spring in the disconnect valve.
First step would be to undo the disconnects and see if anything jumps out at you.
If we had a LA534 Loader hose & connector diagram we could probably narrow it from 4 hoses to 2.

 

[Thomas]

Interested out come to problem....I have same model.

 

[Dave M7040]

I do not see how it could be the loader valve. To me it sounds like one or more of the quick disconnects in the hoses to the boom lift cylinders is going bad. My guess would be a broken spring in the disconnect valve.
First step would be to undo the disconnects and see if anything jumps out at you.
If we had a LA534 Loader hose & connector diagram we could probably narrow it from 4 hoses to 2.

rScotty

I have attached the LA534 assembly instructions.

Dave M7040

 

[Snowlan]

From your description this is my best guess without troubleshooting it myself. When you meet resistance lowering the boom it means you have increased pressure on the side of the cylinder pushing the rod back in. If the valve stem/spring is damaged/weak on the tractor side of the coupling it may be allowing the valve on the loader side of the coupling to slam shut as soon as the control valve is released. With that valve in the coupling seated, no oil can get out of that side of the cylinder so you can't pump oil into the extension end of the cylinder and lift the boom. Relieving that pressure allows the weak spring to get the loader side of the valve off the seat again and everything goes back to normal. I'd check the fitting on the tractor side of the coupling of the hose coming from the far end of the boom cylinder.

 

[Everhard]

I'm assuming you've got quick disconnects for the loader and bucket. swap the 2 circuits so that the valve that rotated the bucket now lifts/lowers the loader arms. If the loader still acts like before (getting stuck) then as indicated above it's the quick connect male end going to the loader. (Okay I'm also assuming your tractor is like mine and the male end is on the lines going to the loader.)

E.

 

[Citydude]

From your description this is my best guess without troubleshooting it myself. When you meet resistance lowering the boom it means you have increased pressure on the side of the cylinder pushing the rod back in. If the valve stem/spring is damaged/weak on the tractor side of the coupling it may be allowing the valve on the loader side of the coupling to slam shut as soon as the control valve is released. With that valve in the coupling seated, no oil can get out of that side of the cylinder so you can't pump oil into the extension end of the cylinder and lift the boom. Relieving that pressure allows the weak spring to get the loader side of the valve off the seat again and everything goes back to normal. I'd check the fitting on the tractor side of the coupling of the hose coming from the far end of the boom cylinder.
View attachment 693114

Thanks or posting the picture. I always wondered how they worked.

 

[Little Kioti]

Awesome information! I will attempt to get out there today and examine the quick disconnects. I will also swap the lines to switch the functions and see if the problem follows. All of your input is greatly appreciated.