1520 3pt valve leaking, HELP

[Barry Bowen]

There is no way to turn off the 3pt. As long as I have the 3pt raised all the way, I have enough for the loader as the leak then is very minimal.

See if this helps figure things out. If I lower the hitch half way and it finds it's spot to stop, I can push the end of the arms down another 3-5 inches and then it will bounce right back up. Does this help with the diagnostics?

 

[J_J]

How about a gate valve or solenoid valve at the input to the 3pt valve. That will shut off all hyd to the 3pt, and give the loader all the fluid and pressure.

One guy on TBN just took his 3pt valve apart and found some bad o-rings.

Locate a parts/service manual and you should be able to break it down and repair it.

There is a spot on the 3pt valve that is the neutral position, where no fluid is supposed to flow. If you raise the lever up, the 3pt should rise and start to relieve at the end of the stroke. .

If you had a gage install, you could see this point when in neutral.

 

[Barry Bowen]

There is no way to turn off flow to the 3pt. It is inside the castings. The priority valve bolts to the trans housing, and the flow to the 3pt is internal from there.

The plan is to rebuild both the cylinder and valve. I was looking to see if any one had any good insights. It is my belief that when things got way way over heated this summer when I was having problems in the steering that I damaged or blew out orings or seals in the valve and cylinder. Chances are they have never been apart since the tractor was new anyway.

What things do I need to look out for on the technical side of doing this particular valve and cylinder. I have the shop, hoist, and tools to do what ever needs doing. I have rebuild hydraulic valves before. I just did the MCV pump and valve on my 706 yesterday, but I think this 3pt valve will be much more complicated then that. I have access to the shop manual no problem, infact I should be getting it this evening.

 

[jenkinsph]

I am still suspecting the valve and would also add the position control linkage has to rotate to move the valve to the center (no flow) position.

If the rockshaft will hold an implement in the up position for an hour or so without dropping down I would think the rockshaft cylinder is okay. If it were bad enough to cause the problems you infer it would come down instantly when you shut down the tractor.

Does the position control work properly? If it isn't the valve would not be moved to the nuetral position. Not familar with the 1520 setup

 

[jenkinsph]

There is no way to turn off flow to the 3pt. It is inside the castings. The priority valve bolts to the trans housing, and the flow to the 3pt is internal from there.

The plan is to rebuild both the cylinder and valve. I was looking to see if any one had any good insights. It is my belief that when things got way way over heated this summer when I was having problems in the steering that I damaged or blew out orings or seals in the valve and cylinder. Chances are they have never been apart since the tractor was new anyway.

What things do I need to look out for on the technical side of doing this particular valve and cylinder. I have the shop, hoist, and tools to do what ever needs doing. I have rebuild hydraulic valves before. I just did the MCV pump and valve on my 706 yesterday, but I think this 3pt valve will be much more complicated then that. I have access to the shop manual no problem, infact I should be getting it this evening.

Before going inside I would check all the external linkage adjustments on the outside. There are several adjustments outlined in the technical manual that are critical for proper operation.

There is a remote possibility that some of the failed Oring is lodged in the system too. If you have to remove the top housing and rebuild the valve and cylinder I would check on the cost of a new transmission pump while you are at it. I had to change one in my 4020 many years ago and it wasn't too costly, better than taking it all apart again.

 

[Barry Bowen]

All the linkage on these is internal. I would do the trans pump now, accept it requires splitting the tractor, so I will be waiting to do that until I have to do the clutch in a year or so.

 

[Tx Jim]

What is IIRC and RS?
As long as the hitch is up completely, loader works fine. With hitch leaver even lowered just a few inches, the big flow starts in the trans and loader does not work.

Barry
If you have flow by lowering the 3pt then you may as well resolve yourself to remove rockshaft housing and replace RS valve o-rings and I'd also recommend replacing RS piston o-ring & thermal relief valve.

Here's a list of the parts required but PLEASE have parts person double check my list of part numbers before ordering parts.
2-T17882 RING,SEALING ADD 1.40 USD 2.80 USD
1-T21641 GASKET ADD 12.75 USD
2-R10093 PACKING,O RING ADD 0.84 USD 1.68 USD
2-R31136 RING, BACK-UP ADD 0.99 USD 1.98 USD
2-L55204 ORING View/Update 1.07 USD 2.14 USD
1-AT21781 VALVE,THERMAL RELIEF ADD 49.45 USD
1-R65621 PACKING ADD 5.46 USD
1-R65620 SEAL ADD 13.25 USD

 

[Zebrafive]

IIRC= If I Recall Correctly
RS= Rock Shaft

It sounds like you have leakage internally in your Rock Shaft Valve.
When you have the arms fully raised and the valve in the raised position, I think the valve being shifted, the oil flow dead ending in the rock shaft cylinder, you get enough flow to operate other hydraulics.

I would rebuild the valve. I would also rebuild the cylinder since I have it a part. I do not think your thermo relief valve is at fault, but would replace it too, since it is a part.

The trans oil pump can be tested without splitting the tractor. JD dealer should have a flow tester to do this.

 

[Barry Bowen]

Here is a link to the JD site for a rebuild kit for the cylinder and valve for 1520.

http://jdpc.deere.com/jdpc/servlet/...vlets.HomePageServlet?search=model&model=301A


I am already resolved that all this has to come off. I got a hold of the shop manual from my uncle yesterday, so I can read all the details on this job.

I also see the complete valve seal kit ar92385 (instead of separates)
spring f3322r
spring r49684

your prices though look about half of what is coming up on line, where are you getting those so I can go there and get stuff instead.

 

[Tx Jim]

Barry
The part # ar92385 you listed if I'm looking correctly doesn't appear to contain all the parts I listed. These 2 part numbers aren't shown(1-R65621 PACKING ADD 5.46 USD,1-R65620 SEAL ADD 13.25 USD) plus this one(T21641 GASKET ADD 12.75 USD). The prices I listed are from my local JD dealer that I log into to llook up parts. Some dealers charge MSRP and some charge MSRP plus a % markup.