valve rebuild.

[ch1ch2]

I have an issue with the lift valve on my NH TN95A. It has been leaking down for a while, it started falling fast or dropping while lifting, (I think float mode), and now it lifts so slow it is hard to get things done. I need to decide on rebuilding or replacing.
All advice is welcome. I will be away from my computer for awhile, so my replies will be slow.
I am going to take it apart this week.
I thought about swapping with a rear remote but the part numbers do not match and a big price difference so I am sure they are different valves.
Do I need to buy replacement seal rings between the valves?
Should I replace all the replaceable internal parts or just the ones I can see might be bad?
Any additional ideas?

 

[oldnslo]

First are you sure it is the valve? Do all other hydraulic functions operate properly and at the expected speed?

Usually if valves are worn to point they are leaking excessively they are not considered repairable.
Have you double checked the following:
Any linkage or cables operating this valve to be sure they are moving the valve spool and allowing it to spring return to the center or home position?

Checked for a corrosion or crud build up in the end caps covering the spools.

With FEL on the ground and engine off move the control lever and observe the spool travel. Does it travel similar distance in both directions?

Does the spool return to same center or home position repeatedly?

 

[cbailey1956]

Are you talking about the 3pt lift or the loader lift circuit? When you said "float" I assumed the loader lift. Anyway it could be a cylinder piston seal issue.

 

[bigdeano]

It's more likely the seal on a cylinder piston, not the valve.

 

[ch1ch2]

Thanks to all.
Yes, it is the valve!
Yes, it is the FEL.
Yes, the valve appears to work properly externally.
I removed the valve today. I should have it apart this weekend.

 

[cbailey1956]

Hopefully it will be in the detent cap area. Have repaired several that were dirty and the spool would not operate properly. Even had water trapped in several and they would freeze up in cold weather. Good luck

 

[wdchyd]

It's more likely the seal on a cylinder piston, not the valve.

X2.....

 

[Tx Jim]

Thanks to all.
Yes, it is the valve!
Yes, it is the FEL.
Yes, the valve appears to work properly externally.
I removed the valve today. I should have it apart this weekend.

Spool valve that is leaking internally must be replaced as a whole unit IE spool & housing because it is a "machined fit".

 

[LD1]

Spool valve that is leaking internally must be replaced as a whole unit IE spool & housing because it is a "machined fit".

x2

And if loader (as in lift arms and not just the bucket curl) are leaking down....it is NOT the cylinder seals. If there are no external (hoses, fittings couplers) leaking, than it IS the valve.

Spools are closely machined metal on metal valves. There are no seals to replace other than the end seals, which if bad would cause external hydraulic leaks.

 

[wdchyd]

And also to add to misery, if it ends up being a worn control valve you'll be doing some major housekeeping to clean up the gritty or rusty contaminated oil that could have contributed to spool wear.