MX6000 - FEL and 3PH Stopped Working

[BackRoad]

2020 Kubota MX6000, HST, 1070 hrs, with FEL, plus 3 Remotes and Fit Rite TnT added 2 years ago:

Using the grapple today and lost the ability for the top section of the grapple to stay open. It would open up as long as the open valve button was actuated, then it would gravity close in 2-3 seconds once the open button was released. It would pull closed tightly, but it would not stay open.

Then about 5 minutes later, all FEL hydraulic operations ceased.

The FEL will not raise, FEL curl does not work, opening or closing the grapple does not work. Then checked the rear remotes (TnT hydraulics) do not work, nor does the 3PH raise.

No difference in symptoms at idle, 1500 or 2300 RPMs, nor after a tractor restart.

The HST does work, at least I was able to move the tractor (dragging the loader along the ground) about 20 feet away from the middle of the driveway. From research on TBN, it appears the HST may have its own pump/hydraulic circuit, so not impacted.

The hydraulic oil sight glass shows clean UDT2 just above mid level.

The tractor has 1070 hours, so another 130 hours before the next scheduled hydraulic filter and fluid changes are due.

Embarrassed that there are two minor hydraulic oil leaks at two different O-Ring boss fittings that I've not been very successful with stopping, but they are months old and have not caused any functional issues previously.

Guessing this might be serious...my uneducated guess is maybe the main hydraulic pump (?).

Just wondering if there are any "...You might check this..." suggestions to eliminate possible silly stuff, before I transfer ownership of my retirement bank account over to Messick's for open heart surgery.

Thanks,
Terry

 

[ptsg]

On most tractors, and I believe this one too, the steering pump is what feeds the HST.

Also, on this tractor, it uses a tandem pump. One section for the loader, remotes and 3 pt and the second, smaller section for the steering, HST and PTO valve on some tractors.

At first, I thought it stripped the splines on the pump input shaft but since it's a tandem pump and you still have HST and steering (I assume), this is not the case as the same driveshaft drives both sections of the pump.

After the bigger pump, it goes to an hydraulic block that then feeds the loader valve. On this block, the only thing that could possibly go wrong is the relief valve. Maybe some trash managed its way through and the relief valve got stuck open.

This would be my first go to component to investigate as it would cause the loss of loader, remotes and 3 pt.

Here is a parts view of the hydraulic block. Part #80 is what I suspect is stuck open. Or, although very unlikely, the spring #70 broke.

 

[bdhsfz6]

3rd function valve??

 

[Harry in Ky]

The first sentence holds the key. The grapple wouldn't stay open. That's by no means a pump related problem. Next clue is the "button". That says there is a solenoid valve somewhere in the mix. My bet is the bulk of the problem is right there.

 

[BackRoad]

Y'all give me hope!

I plan to spend some time tomorrow morning to further isolate focusing on the 3rd function valves and added rear remotes.

 

[BackRoad]

And Thank You!

 

[oldnslo]

Is this true 3rd function that is NOT controlled by curl dump movement. If yes then suspect Harry may be on the right track.

Is 3 rd function plumbed before or after the FEL valve? If before would definitely point that direction if after should only effect 3 point and not loader.

 

[BackRoad]

OK, perhaps I'm starting to understand the logic a bit clearer now...

The hydraulic flow must hit each of the valves in series from the pump.

Since nothing is working, the failure is likely the first valve after the pump, which seems to be preventing hydraulic fluid from flowing downstream.

Since the 3rd function started to go south first, that valve is the most interesting candidate to investigate first, and is likely to be the first in the lineup.

Fingers are crossed that it's this straightforward tomorrow!

 

[Harry in Ky]

Actually, the third function could be anywhere in the system. That depends on the fastest, easiest place the installer found to put it. My logic for starting there is simply because 1) I don't like electric valves, and 2) it seems all too often strange hydraulic problems occur and get reported on sites such as this end up being related to one.

 

[ptsg]

I hope dealers know better to not install 3rd function valves right after the pump. A lot of tractors don't have an hydraulic block with a relief right after the pump, so having the 3rd function there and considering most 3rd function valves don't have relief valve, can only mean bad stuff happening.