Kubota L3600/LA680 hydraulics problem. Need help

[houser52]

>First a little background-

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.

Yesterday 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, with the bucket or grapple, there was a very rough shutter/chatter feeling to the hydraulics and it was slow. Rpms made no difference.
Also, when moving the joystick all the way to the right, when dumping, it made a sound like the relief valve was opening and the tractor's rpms slowed but raising and lowering the boom is normal.

I took my gauge and tee'd 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 as to what's going on?

Thanks

 

[LD1]

The chattering or shuttering sounds like air.

You had the system opened up installing the new components. Cycle everything back and forth fully several times to work air out of the system and see if it goes away.

 

[houser52]

Thanks but I already tried cycling everything quite a few times and didn't fix it. Maybe have gotten a little worse.

 

[kennyd]

Sounds like the regen or regenerative function of the dump circuit kicking in, does it work ok if you only move the joystick a little to the right? Here is an old thread that explains it well, I can link more later if needed.

http://www.tractorbynet.com/forums/kubota-buying-pricing/9403-3-position-valve-vs-4-a.html

 

[houser52]

Sounds like the regen or regenerative function of the dump circuit kicking in, does it work ok if you only move the joystick a little to the right? Here is an old thread that explains it well, I can link more later if needed.

http://www.tractorbynet.com/forums/kubota-buying-pricing/9403-3-position-valve-vs-4-a.html

Thanks Kenny.
I had already read about the regen function sometime ago but since the loader had never done this before I thought it couldn't be regen related. Moving the joystick to the right(dump position) a little or all the way results in the hydraulic vibration. All the way to the right is when dumping slows down, I can hear the rpms slow and a whine like the relief is opening.

I've had the loader for about 15 years and this just started yesterday.

 

[kennyd]

Ok, good.
My next guess would be a QD that is not acting right-causing a restriction.

 

[houser52]

Ok, good.
My next guess would be a QD that is not acting right-causing a restriction.

Thanks again.
After doing some research today, couplers were on my check list. There are only 2 QT couplers that plug into the hydraulic block. I replaced those 2 associated hoses while I was plumbing in your diverter and the other hoses I replaced didn't have couplers. I didn't install 2 new QT couplers at the hydraulic block because they had been working fine but I'll check them again.

 

[houser52]

Ok, good.
My next guess would be a QD that is not acting right-causing a restriction.

kenny-
It was dark when I got home last night but I disconnected and reconnected the three QDs at the hydraulic block. After doing that the dump cycle is still slow. It did not shutter/chatter but everything was still cold and not at operating temperature. I don't know if the cool fluid temp would not cause it to chatter or not.

I assume that a QD can be bad internally without any visible signs of a problem so one of the easiest things I'll try first is to change out the 3 QTs one at a time. I just ordered some QDs from you.

One other thing I just thought about was that a couple months ago I increased the hydraulic pressure. The factory setting was supposed to be 2489 psi but was low at 2200 psi. I added 1 washer which brought it to 2600 psi, which was verified with a gauge tee'd in at the bucket cylinder. Would increasing it just 100 psi over the factory setting cause the dump problem?

 

[kennyd]

QDs can go bad internally, and cold fluid can cause strange things but I doubt it's cold enough for that yet. I don't believe raising your pressure is a big deal either, that seems unrelated to your current problem.

 

[houser52]

Thanks kenny. Hopefully I'll get the QDs in a few days.

I've still been searching online for other possible causes. Suction hose hole or cracks and dirty suction screen have been mentioned a lot. My suction hose looks ok but that doesn't mean there's not a pin hole somewhere. I don't know if my L3600 even has a suction screen. It's not mentioned in the owner's manual and I can't find in info about it online.