Loader Valve / Curl function diagnosis

[J_J]

Your only other option is to tee each gauge in each work port with cyl connected.

A test set like this would have worked well.

 

[GPintheMitten]

Thank you JJ and LD1. With guages directly mounted to the curl ports on the loader valve (not tee-d in), when I push the joystick out to the right, the top guage shows max pressure (2000) and when I let the joystick go, it bleeds back. Then when I push the joystick back in to the left, the bottom guage stays at zero. So I can't see any reason to plumb the hard lines back and open the lines at the cylinder to check on oil flow. With no pressure on the lower guage, it seems to me and my local hydraulic guy that the problem is internal to the loader control valve.

I'm shopping for a new or used loader control valve now. Thanks again.

 

[GPintheMitten]

Btw, I just took the guages out and reattached the curl lines, removed both quick connects from the lines. I applied pressure and got oil flow on one line but zero oil flow the other way. One last test verified no flow.

 

[LD1]

It does sound like a valve.

ITs hard to see in that picture, where you lines are hooked, but is that the actual valve? How is the joystick connected to that? There could be a problem with a linkage or something that when you pull the lever to the left that you arent actually moving the spool...

 

[GPintheMitten]

It does sound like a valve.

ITs hard to see in that picture, where you lines are hooked, but is that the actual valve? How is the joystick connected to that? There could be a problem with a linkage or something that when you pull the lever to the left that you arent actually moving the spool...

Yes that is the actual valve. I wasn't sure the spool was moving either but after I took the valve off, and removed the cans from the bottom, I could see the spools were moving. I could also see them moving from the ports.

I ordered a used valve this afternoon. New from Kubota was an astronomical $825 plus shipping. The used one I ordered is guaranteed for 1 year and cost $675. Still outrageous but I need it and didn't want to buy a universal valve and have to find a place to mount it and then replumb all the lines.

 

[LD1]

Whats the return policy, just in case this turns out to be something different?

 

[GPintheMitten]

I'm beat now but later I will remove the current valve and take some better pics. With the rear tire off, fender off, and backhoe subframe off, I can wiggle the valve assembly out with joy stick attached.

 

[GPintheMitten]

Whats the return policy, just in case this turns out to be something different?

Not sure of the return policy but I would think I could return it with some sort of restocking fee. After all, it is a used part.

 

[GPintheMitten]

Here's some pics of the loader valve. The linkages are tight and working. This mounts to the right side of the transmission housing, a few inches forward of the axle. When mounted the joysticks lines up along the right leg halfway from the hip to the knee. The goldish colored assembly is a locking mechanism that can be engaged to keep the joystick from moving.

You can't see it in the pics but I can look in the 4 working ports and see each spool move up and down as the joystick is moved.

I will remove the back plate that attaches to the tractor and the joystick and locking mechanism and remount them on the new loader control valve when it comes.

I will report back in a few days after I get it back together. Hopefully all this diagnosis was correct.

 

[LD1]

Really odd that the spool is actually moving yet no movement of the loader, and the other functions work.

Hope the new valve fixes it. Maybe tear apart the old valve and see if something is broke or cracked

 

[GPintheMitten]

Yah, I plan on tearing into for curiosity sake. In theory, you can replace the spools but they are such close tolerances, my concern is that the casting could be scratched or cracked.

 

[J_J]

The problem with your valve is almost inconceivable.

The grooves in the spool are cut to allow a flow path from the pump side through the valve in neutral.

When you move the lever, you are moving the spool to match with another port.

In the no regen position, the flow from the pump goes into the spool groove and to one of the work ports, and opens another grove for the cyl fluid to escape.

Even if the port was blocked, the flow would pass over the relief valve.

So, since the problem started, you have not seen any flow from the one work port.

It could be that a piece of the valve has broken off inside the valve.

When you remove the spool, and if it is complete, then the problem is internal and you might never see why.things are not working correctly.

Are you also saying that after you dumped the bucket, it never curl back up, or you curled up and it never did dump after that.?

 

[Leejohn]

I don't see a relief valve. Is there one before the valve on the tractor?

 

[GPintheMitten]

I curl it up but can not dump. Sometimes I notice that it has gradually dropped (dumped) a small amount. I can curl it back up but I can not dump it.

This condition started after I accidentally abused it. I had the bucket dumped and was grading forward in the evening when it was getting dark and hit a farm gate at the hinge side where it is bolted to a cemented in 6x6.

At the time, the dump function slowed and eventually stopped altogether.

So while it may be unusual, the system did take a big hit

And to answer your other question, since it failed I believe there is no flow at all to the dump function. That is, I can not dump the bucket.

 

[GPintheMitten]

I don't see a relief valve. Is there one before the valve on the tractor?

I'm told that there is a relief valve internal in the control valve.

 

[LD1]

That shock load might have cracked an internal casting. Although I would thin there should still be enough flow to allow gravity to dump the bucket.

 

[J_J]

I'm told that there is a relief valve internal in the control valve.

Yes, there is a relief valve in the valve.

Item #60 in the parts manual.

It uses shims to adjust the pressure.

It is under a hex plug on the valve.

 

[J_J]

It is maybe to late now, but you could have coupled in a new valve in place of the old valve using compression fittings. Cut off the banjo fittings and use compression fittings

New valve from Surplus would be about $250.

 

[Leejohn]

I don't recall anyone telling you to check the load checks in the curl and dump. It might got broken up and got pushed into the galley of the dump.

 

[GPintheMitten]

I don't recall anyone telling you to check the load checks in the curl and dump. It might got broken up and got pushed into the galley of the dump.

When I took the valve into the hydraulic shop, he looked at both poppet (load check) valves and he said they were ok.