Please help me understand what's going on with my hydraulics

[Kubota Tee]

I have a Kubota Grand L5740-HST tractor and use it all year round on our acreage - everything from dirt work to snow plowing to mowing. It's a very handy machine for sure. This past summer, I had a linkage cable break that connects the FEL joystick to the hydraulic valves rendering the FEL up/down function inoperable. I was able to find a new cable (not easy) and get it installed (had to remove the rear wheel), feeling pretty proud of myself for completing this repair. After the repair, everything seemed to work properly.

Some time afterwards, I started noticing that the FEL up/down function would occasionally operate only at a snails pace. I learned that if I combined the up/down function with either curl or dump functions, it seemed to operate at normal speed. I found this to be quite strange. At this point, I was thinking that perhaps I did not adjust the new cable linkage appropriately when I installed it.

Fast forward to this winter, I hooked up my FEL mounted snowplow and it's associated hydraulic hookups for angle adjustments and similar to the FEL up/down function the angle adjustment on the snowplow would occasionally operate at just a snails pace. At this point, I'm starting to wonder if I have a major hydraulic issue. I check the hydraulic fluid and it is at the proper level (FEL in full upright position, 3 pt hitch fully raised).

Now I'm ready to load it up on the trailer and take it to my nearest Kubota dealer / service center with fears of major $$$$ needing to be spent on getting it fixed. As I'm getting it ready to be loaded, I decided to work through all the hydraulic functions so that I can give the service department a full rundown of the issues and hopefully save them time (and my $$$) on diagnosing. This is when I discovered how/when the snails pace experience occurs.

Here goes - perhaps someone can help me understand what's going on. If my 3pt hitch is in the full up position, the FEL up/down as well as the snowplow angle function will quickly slow to a snails pace. Just the slightest move of the 3pt hitch down from the full up position and everything works normal. This is very repeatable!! And now that I know how to make it work properly, I decided to NOT take it to the dealer. However, the mystery still remains. Can anyone give me a clue as to what is going on here?

Thanks in advance!

 

[seville009]

I’m no mechanic, but from my own use of hydraulic machinery, I wonder it the 3 pt is still trying to lift (even though it’s all the way up) and therefore robbing power from other hydraulic functions.

On my MF1540 hst, I have to manually center the hst foot pedal to the neutral position, or else it will “whine” a bit (even though the tractor isn’t moving).

 

[the old grind]

Check and reconnect all QDs, not just the ones up front on the loader arms.

Symptoms sound like the same one line is affecting the loader valve, so ops with the lift spool would be weak both with and without a diverter in use.

Regen on the bucket (dump) can confuse observation as flow path is altered. There should be a detent on the dump function. Try both with and w/o going to that position to see if it acts differently.

 

[nybirdman]

Had/have the same problem on my L4240 HST,the three point is out of adjustment and is going in relief robbing the hydraulic functions.
Mine was to the dealers three times for this( not fixed by them),as long as I leave the three point slightly off full up everything works as designed.

 

[the old grind]

Position feedback lever should be properly adjusted. (not that difficult to DIY)

When in doubt leave 3PH near middle position and continue testing the rest.

If OOP and causing hydro to go into relief it would affect all loader functions, not just lift or curl by themselves.

 

[RickB]

Position feedback lever should be properly adjusted. (not that difficult to DIY)

.

^^^^This. Just to clarify, it is the 3point (rockshaft) position feedback linkage that needs attention.

 

[Dave M7040]

I have attached the 3 pt feedback rod adjustment procedure.

Your loader valve cables need to be properly setup. I have attached WSM pages from a different model loader but most cable operated ones are the same.
In brief, you lock the joystick. Most joysticks have a lock to avoid inadvertent movement when driving. You disconnect the cables at the spool valves (2).

The spool valves with no cables attached will be centered. Now adjust the cables so that the pins connecting the cables to the spools just slide into place.

If a cable is pulling on a spool valve even a little hydraulic pressure will be bled off and downstream hydraulic systems like the 3 pt hitch and remotes will not operate properly.

Dave M7040

 

[Kubota Tee]

seville009 - I think you may be on to something. There is a different sounds that I am hearing when the 3pt is in the full up position and the FEL is running very slow. It does sound like it is laboring, as if it is still trying to lift the 3pt.

 

[Kubota Tee]

Had/have the same problem on my L4240 HST,the three point is out of adjustment and is going in relief robbing the hydraulic functions.
Mine was to the dealers three times for this( not fixed by them),as long as I leave the three point slightly off full up everything works as designed.

nybirdman - this sounds like what is happening on my tractor. I will be researching how to make the adjustment, but in the meantime, it helps to know what is going on and how to overcome the issue by simply lowering the 3pt a bit from the full up position.

 

[Kubota Tee]

Position feedback lever should be properly adjusted. (not that difficult to DIY)

When in doubt leave 3PH near middle position and continue testing the rest.

If OOP and causing hydro to go into relief it would affect all loader functions, not just lift or curl by themselves.

Old Grind - do you have any info on how to adjust the position feedback lever for the 3pt? I'd like to take this on myself if it is not too difficult.