JD 950 FEL Creep

[ChoPChoP]

Bought a used Model 70 FEL and valve a few months ago, installed it and everything seemed fine. Today while mowing the field I noticed the bucket kept creeping down. It seemed to get worse the longer I cut.
My first guess would be a problem with valve but I am a real newb to hydraulics and very open to suggestions.
If it is the valve , is that something that needs to go to a shop to get rebuilt or something I can do myself with the right parts? What else could it be?

 

[J_J]

The cyl seals could just be worn out, and leaking. Double check that the valve levers pop back to neutral.

 

[J_J]

You can check the cyl for internal leaking by putting a needle valve at the work port for the lift cyl and start the tractor, raise the lift arms up, and then closing off the needle valve. Shut off the tractor. If the lift arms fall then you know the fluid is bypassing the piston seals.

It could be one or both cyl leaking. Hot fluid is thinner,and may leak down faster than when cold.

You can rebuild cyl, and some valves, but if the spools are worn, it is best to get a new valve.

 

[ChoPChoP]

You can check the cyl for internal leaking by putting a needle valve at the work port for the lift cyl and start the tractor, raise the lift arms up, and then closing off the needle valve. Shut off the tractor. If the lift arms fall then you know the fluid is bypassing the piston seals.

It could be one or both cyl leaking. Hot fluid is thinner,and may leak down faster than when cold.

You can rebuild cyl, and some valves, but if the spools are worn, it is best to get a new valve.

J_J Thanks for the reply, I was hoping you would spot this post. I've learned a lot about Hyd simply reading your replies here. Really appreciate the way you have of keeping it simple too. :thumbsup:

I don't have a valve to try what you suggested but I did raise the boom and turned off the tractor. I could see the bucket lower very very slowly and also found a very small amount of HF under the valve. It was more on the curl side of the valve stem at the bottom than on the boom side, but it is leaking.

I priced the cylinder kits at jdparts.com, they are $45.50 each so if I do it myself it's <$200 all 4 cylinders. The valve doesn't have a rebuild kit but all the O-rings, washers, bushings and springs only added up to $53.00. Looking at the parts diagram it does not look very complicated so I may try that myself too.

My next question would be. How would I know if the spools are worn when I take the valve apart?

hmm if the valve is shot, maybe I can install a 3 spool and add a Hyd.
Top link or 2 joysticks and put on a side link too!! Somebody stop me please!!

 

[Mechanos]

You said you bought a 70 loader and a valve. Is the valve a "stand alone" unit that just bolts to the loader boom? or is the valve integral with the rockshaft cylinder head?

I would be leaning more toward a problem with the valve. Like JJ said, it is possible that the cylinder piston seals are worn, but given what you described, I'd look at the valve first.

 

[ChoPChoP]

The valve is the same as what originally came with the tractor. It is mounted in front of the rocker arm controls on the right side of the seat. Here's a PDF attachment of the valve. The numbers are covered by the mounting plate so I am not sure this is it but it sure looks like it.

It's also a Model 75 loader taken off a JD 950 with a blown engine, not a model 70 like the first post.

Thanks for the reply Mechanos

 

[J_J]

ChoPChoP,

You could remove the loader valve and take it to a hyd shop for testing. They should be able to test the PRV, spool internal leakage if any, spool seal leakage, check out the spring centering, load check valve, float, etc.

If you know the cyl are good, you can lift a load and release the lever to neutral, and shut
off the engine. If all things are working to specs, the load will hold. If you want to see the leakage rate, remove the hose from the tank port, and the PB port if used. Any fluid coming out after a normal valve drain is coming from the cyl via a worn spool. Some manufacturer may have a 10 drops per min rate, and others more ore less depending on precision of manufacturing.

Should you need to replace the FEL valve, here are a few choices.

Surplus Center - 2 SPOOL COMPACT 10 GPM JOYSTICK CONTROL VALVE

Surplus Center - 2 SPOOL 25 GPM JOYSTICK LOADER CONTROL VALVE

 

[ChoPChoP]

ChoPChoP,

You could remove the loader valve and take it to a hyd shop for testing. They should be able to test the PRV, spool internal leakage if any, spool seal leakage, check out the spring centering, load check valve, float, etc.

If you know the cyl are good, you can lift a load and release the lever to neutral, and shut
off the engine. If all things are working to specs, the load will hold. If you want to see the leakage rate, remove the hose from the tank port, and the PB port if used. Any fluid coming out after a normal valve drain is coming from the cyl via a worn spool. Some manufacturer may have a 10 drops per min rate, and others more ore less depending on precision of manufacturing.

Should you need to replace the FEL valve, here are a few choices.

Surplus Center - 2 SPOOL COMPACT 10 GPM JOYSTICK CONTROL VALVE

Surplus Center - 2 SPOOL 25 GPM JOYSTICK LOADER CONTROL VALVE

Called the local Hyd shop today and asked him about testing the valve. After explaining the problem to him, he suggested switching the boom and curl hoses to see what happens. I tried that and the boom still goes down. The curl is not moving at all plugged into either port. Does that mean it's the cylinders? He is quoting me 1 1/2 to 4 hours a piece to rebuild and test them. He said sometimes they just don't want to come apart so he can't give me a fixed price.

 

[J_J]

Use a hyd gage to test the pressure from the work ports of the valve, Plug the gage into each of the work port hoses. Active the valve until the relief sounds. If you get full relief pressure, then the valve is good.

 

[Mechanos]

... Does that mean it's the cylinders? He is quoting me 1 1/2 to 4 hours a piece to rebuild and test them. He said sometimes they just don't want to come apart so he can't give me a fixed price.

I can sympathize with that. I just rebuilt two of my cylinders last week. The first one took me about 2.5 to 3 hours to get it apart... about 15 minutes to rebuild and put back together. The second one came apart in about 5 minutes and took about 15 minutes to rebuild and put back together.