Loader Lift with Empty Bucket Strains Engine: Valve problem?

[Whitebird]

Hello, All:

I've been moving a lot of gravel with the FEL on my Kubota L245DT. On two separate days now I have had a hydraulic problem show up after a few hours of work.

When I raise the bucket (empty or full), the engine strains like I'm really working it. The tilt/scoop joystick seems normal, except that I think it's begun working slower than usual. The first time this happened I did a couple more cycles then shut it down for the day. Next day, it worked fine for a few hours, then the problem started again.

Here's one clue and I'm wondering if it's related: Ever since I got the tractor (50 hrs ago), when I ease back on the loader lift joystick (up-down), the bucket starts sinking; then as I pull back further, it lifts like it should.

Could it be that something has happened to the joystick valve such that when lifting, fluid is trying to flow both directions (trying to lower and raise the bucket) at the same time? Seems like that would strain the engine: it would be working against itself.

Normally, my hydraulics are strong in all directions: the FEL will lift the front end of the tractor or the back end (if I try to pick up something too heavy) and that's with filled tires and a heavy mower on the 3PH.

The hydraulics still "hold" fine; they do not slowly sink. When I turn the tractor off the bucket and 3PH will stay up indefinitely. Also, I'm using TSC's "tractor fluid" (similar to UDT) and have recently topped it off, since I have a leak in the power steering cylinder.

I've never worked on hydraulics, though I understand the basic idea of routing fluid with valves to do work. So any advice on where to start troubleshooting would be appreciated.

Thank you!

 

[Whitebird]

I've run the tractor a few more times and realize that the hydraulic straining affects the 3PH raising as well, so it's not the loader joystick block but must be further back in the system.

The hydraulics work fine when I start, then after an hour or two of loader work, I begin to get that same straining. That makes me think it has something to do with it getting hot. But how would getting hot affect the hydraulics?

Any help would be appreciated.

 

[J_J]

Do you keep the 3 pt lever in neutral when using the loader?

If you leave the 3pt lever in the raise position, the pressure will build up in the hyd circuit.

Have you looked at the load check valve for damage or debris?

If you had a hyd gage, you could see the pressure for any hyd action.

You might check the spool centering springs to see if they are centering the spool when you release the lever.

 

[oldnslo]

Engine straining indicates that something is restricting the oil flow from the pump. Does this model have a priority flow control that directs some flow to the steering and the balance to implements? If yes this Priority flow control could possibly be binding due to heat increase but that would be a long shot. Do you have service manual that shows the hydraulic schematic or diagram?

 

[Whitebird]

Do you keep the 3 pt lever in neutral when using the loader?

If you leave the 3pt lever in the raise position, the pressure will build up in the hyd circuit.

I believe I'm leaving it in neutral. I keep the 3PH raised about halfway with a heavy mower on it to counterbalance some of the weight in the bucket.

Have you looked at the load check valve for damage or debris?

I don't know where to find this. The parts manual I have doesn't include the loader and there is nothing on my control block that looks like what the manual shows as the check valve. Do you see it in any of these pictures?

Engine straining indicates that something is restricting the oil flow from the pump. Does this model have a priority flow control that directs some flow to the steering and the balance to implements? If yes this Priority flow control could possibly be binding due to heat increase but that would be a long shot. Do you have service manual that shows the hydraulic schematic or diagram?

I do not believe this has priority control. Certainly, there is no visible adjustment on the hydraulic system other than to the speed of the 3PH lift (visible at top of 1st pic.) I don't have a manual that shows the loader hydraulics; I will call Messicks tomorrow and see if they can help me find one.

 

[J_J]

Look for a hex bolt inline with the spool.

Maybe on the bottom of valve.

It will have a spring and seat assembly.

On this prince valve, they are on the side of the valve.

 

[Whitebird]

Well, I feel stupid, but maybe this will help someone else. It occurred to me this morning that I ought to double check the tranny oil screen filter. Well, sure enough, it was gunked up. After cleaning that, it has run normally for several hours, so I'm hoping that was the problem. Makes sense that it would take a lot of HP to pull oil through a gunked up filter. As to why it would work until it got hot, I still don't know.

For anyone else cleaning or changing your filter, be sure to have a cork handy to plug the hole when you pull the filter out. I think the one I used was about 7/8" on the small end. Even so, I lost maybe a pint of oil.

Thank you, J_J and oldnslo, for taking the time to troubleshoot with me!

 

[J_J]

Thanks for letting us know the cause of the problem.

Most people never answer back.

 

[J_J]

Thanks for letting us know the cause of the problem.

Most people never answer back.