Loader valve.

[ch1ch2]

My TN95A has had issues with the lift valve on the FEL. It will leak down from full extension to on the ground in 3 to 4 hours. It has now gotten to the point of not lifting at low rpm and barely lifting at high rpm. I want to take it apart and rebuild it, but I am not sure what is going to happen. It is a mid mount with 3 hard lines and the two hoses lines going to the quick disconnect bracket.
My concern is that when I disconnect the hard lines that all the transmission fluid will drain. I am ok with a few gallons from the line or hoses but not with having fluid from the reservoir draining.

 

[ch1ch2]

In reading my manual, it says the high pressure pump in on the right side of the engine. Which I would think would not allow the reservoir to drain. I am not at the farm now so I have to go by my best recall, which is a bad thing. I recall a pump on the left side of the engine and I recall looking at the hard lines and the two on bottom came from the rear while the one on top went to the top of the transmission.
So the book and my recall do not match.
I wonder about the book also. The contents page and the chapters do not match. The information seems to be correct for the most part, except for my memory.

The book says" In the mid-mount valve stack, the valve operating buck control is self-centering, while the valve operation boom control is self-centering with float in the down position."

That makes sense. Only the fact that mine seems to work differently. I have never had float in the down position and there have been times when raising the bucket that the buck fell.

I did buy this tractor used. Now I was thinking if someone worked on the valves before and turned it upside down or something. Pulling back on the joystick causes the arms to lift. The only thing I can think of would be that the valve spool is in the valve body backwards. Is that possible?

I will keep reading and I am sure I will come up with more questions.

 

[prichard]

Not familiar with your tractor but...

I thought back to raise is the norm. Does manual say forward to raise? Also on mine float is a detent beyond down.

 

[ch1ch2]

Not familiar with your tractor but...

I thought back to raise is the norm. Does manual say forward to raise? Also on mine float is a detent beyond down.

The manual uses the terms lift phase and lower phase.
Mine is set up pull rearward is lift and push forward is lower.

 

[/pine]

The first thing I would do if you have not already done so...is remove the bottom caps from the spools and make sure the nuts (etc.) are secure and keeping the springs tight...Generally these caps should be removed and inspected for condensation, rust etc...sometimes the weep holes get clogged with grease...

A loose nut/spring can possibly cause faster than normal leak down...FWIW...

 

[KYErik]

If you open the system (take a hose loose, remove the valve etc) at a point below the level of fluid in the reservoir and the return hose is not routed above the level for fluid in the reservoir, it will likely continue to leak from the reservoir (flowing backwards through the return hose).

I think that most tractor loader valves use backwards to lift the bucket and forwards to lower the bucket. Like prichard said, pushing the lever all the way forward will put it in the "float" position where it will "stick" until you pull it back up to the center position.

There is a good chance that the valve is OK and your lift cylinder piston seals are leaking. In my experience, the piston seals will wear faster than the the valve will.

 

[ch1ch2]

The first thing I would do if you have not already done so...is remove the bottom caps from the spools and make sure the nuts (etc.) are secure and keeping the springs tight...Generally these caps should be removed and inspected for condensation, rust etc...sometimes the weep holes get clogged with grease...

A loose nut/spring can possibly cause faster than normal leak down...FWIW...

I will look at this. I did not think of that.

 

[ch1ch2]

If you open the system (take a hose loose, remove the valve etc) at a point below the level of fluid in the reservoir and the return hose is not routed above the level for fluid in the reservoir, it will likely continue to leak from the reservoir (flowing backwards through the return hose).

I think that most tractor loader valves use backwards to lift the bucket and forwards to lower the bucket. Like prichard said, pushing the lever all the way forward will put it in the "float" position where it will "stick" until you pull it back up to the center position.

There is a good chance that the valve is OK and your lift cylinder piston seals are leaking. In my experience, the piston seals will wear faster than the the valve will.

I have eliminated the cylinders as an issue by isolating with the quick disconnects. The cylinders do not move when removed from the tractor.

 

[PILOON]

The FEL gradually leaks down?
That is most probably the valve itself, probably some debris has worn the shaft or body.*
Not much to do other than replace the valve itself IMO.
My friend had same problem (not same tractor) and he simply installed a new valve, cost him $200.
You have eliminated the cylinders so only the valve remains as the cause.
I would very much doubt your pump is the problem.

*Hydraulic valves are merely VERY close tolerance piston like that very tightly fit the valve body and any scoring will cause leak down.
They can be directly operated or remotely by Boden cables, some may use push pull rods.

 

[ch1ch2]

The FEL gradually leaks down?
That is most probably the valve itself, probably some debris has worn the shaft or body.*
Not much to do other than replace the valve itself IMO.
My friend had same problem (not same tractor) and he simply installed a new valve, cost him $200.
You have eliminated the cylinders so only the valve remains as the cause.
I would very much doubt your pump is the problem.

*Hydraulic valves are merely VERY close tolerance piston like that very tightly fit the valve body and any scoring will cause leak down.
They can be directly operated or remotely by Boden cables, some may use push pull rods.

I am hoping that it could be a o-ring or debris in the valve body. If I have to replace the whole valve, then the question becomes whether to replace with NH valve and at what cost? Who makes the NH brand valve, and /or other sources for it? I have a grapple that I am running off of the rear remotes. Should I get a replacement from Surplus Center with the third function for the grapple?

I am still not at the farm to double check things and I am not comfortable with the way the arms free fall. Could that be a problem with the way it was installed? I have not understood the manual after reading it 6 times. It talks about a release feature, where when the cylinder reaches full extension, pressure reaches max and the valve spool returns to center.
Sometimes the arms falls while trying to lift. Then nothing works on the lift until I return to center.
If I have this release, then max pressure is being reached before it is fully up. What problems could cause pressure problems inside of the valve body and no where else?
So much I do not understand.