L3600/LA680 loader hydraulics issue

[houser52]

Within the last few months I've done a few things to my Kubota...

1. The FEL had always felt a little weak. I bought a gauge and checked the pressure at 2200 psi which was lower than the factory psi of 2498psi. I added 1 #10 SS washer which brought it up to 2600psi.

2. Added a diverter valve kit which I got from Kenny at bolt on hooks.

3. Had new hoses made for hooking up the diverter and new hoses to run to a new grapple

4. Plumbing was checked and rechecked.

5. Changed the hydraulic fluid and filter using Super UDT and Kubota filter.

Today was the first time that I actually got the chance to operate it for any amount of time since everything was finished. I had run the tractor and loader during the time I was working on the additions and everything was fine.

Now the problem...
What I ran into today had never happened before. When dumping there was a very rough shutter/chatter feeling to the hydraulics and it was slow. Also, when moving the joystick all the way to the right, when dumping, made it sound like the relief valve was opening and the tractor's rpms slowed.
Raising and lowering the boom is normal.

I took my gauge and tee'd it back into the dump cylinder and it was still reading 2600# when at full dump.

I couldn't find any leaks anywhere and the hydraulic fluid is full. I also operated the boom and bucket to full lift and dump several times to bleed out any air. It still shutters.

does anyone have any ideas of what the trouble is?

 

[houser52]

Anyone care to make a guess as to what's going on?

 

[North Idaho Wolfman]

Sounds like a restriction in the system, most likely at the diverter valve or hoses that you added.

You also could have gotten some junk in either the diverter valve or the control valve that is causing the issue.

 

[houser52]

Sounds like a restriction in the system, most likely at the diverter valve or hoses that you added.

You also could have gotten some junk in either the diverter valve or the control valve that is causing the issue.

Thanks. I blew out the diverter with the air hose but the new hoses could have had something in them.

From what I can find out, some kind of a restriction is very possible. When running the new hoses I used the 3 original quick connectors that were running to the hydraulic block. I was thinking there might be a restriction in one of those or they could be messed up inside. Swapping them out one at a time is what I was going to try first.

Do you recommend trying something else first?

 

[lugbolt]

IIRC, the hydraulic block has a slotted screw in the middle of it. Make sure it's turned all the way one way or the other. One way turns it off, the other turns it "on", but it needs to be fully one way or the other, not in between.

 

[rbargeron]

Is roll-back function normal? If not, the curl/dump circuit hoses may have been switched during the mods (were they disconnected?). Try swapping them and see if it goes back to normal.

If the LA680 valve works like my LA1150 valve, in dump mode pressure is applied to both sides of the cylinders. The cylinders extend because the area above and below the piston aren't equal. The bucket is prevented from dumping abruptly, allowing better control of heavy loads. Its also why performance is goofy with the hoses switched, or when trying to use the valve to run other things.

 

[houser52]

IIRC, the hydraulic block has a slotted screw in the middle of it. Make sure it's turned all the way one way or the other. One way turns it off, the other turns it "on", but it needs to be fully one way or the other, not in between.

I'll double check that. Thanks.

 

[houser52]

Is roll-back function normal? If not, the curl/dump circuit hoses may have been switched during the mods (were they disconnected?). Try swapping them and see if it goes back to normal.

If the LA680 valve works like my LA1150 valve, in dump mode pressure is applied to both sides of the cylinders. The cylinders extend because the area above and below the piston aren't equal. The bucket is prevented from dumping abruptly, allowing better control of heavy loads. Its also why performance is goofy with the hoses switched, or when trying to use the valve to run other things.

I just reread your post and now it's got me wondering about it. They were in fact disconnected because I had to have new length hoses made.

Roll back seems to be normal but I just may have not noticed anything different. I was certainly trying to be careful when hooking everything up by switching each hose one at a time but stuff happens.

If the hoses were switched, would pulling the joystick to the left to roll it back, still roll it back like it normally would? Looks like if they were switched, when moving the joystick to the left to roll back, the bucket would dump. I might be thinking about things all wrong when it comes to hydraulics.

If I were to switch the hoses just to try it, could I damage something?

Thanks for your reply and making my head hurt.

 

[rbargeron]

If the curl pipes were switched, pushing the lever right would roll it back.

You won't damage anything trying it. The worst will be a hissing relief valve and no motion. If any hose is wrong, another has to be too. It can get confusing pretty fast.

I noticed the pressure-on-both-sides thing when I used my loader valve for a front blower with the curl circuit turning the chute left/right. It would only work connected one way. The other way the chute went the same way for either direction of the lever. Connected right its slow in one direction because its fighting itself in the chute cylinder.

I am wondering if they get pressure on both sides by putting some kind of check relief in the control valve on the exhaust flow from the rod end of the cylinders. If so, a malfunction in that could be what's eating your lunch.

Unfortunately I'm a little stupid about this stuff - and I can prove it Take care - and good luck Dick B

 

[North Idaho Wolfman]

As other have said, swapped lines on newer valves can lead to some erratic operations.

Yes try swapping the lines and see what you get.

 

[houser52]

Since it won't hurt anything to swap them, I'll give it a try. If it works, you guys will be heroes!