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Discussion Starter · #1 ·
I went to a bush hog job today and pto would not engage. PTO slowly turned and sped up a little with more throttle without load. Seemed to be slipping. A bit of research revealed it could be bad pto solenoid or pto valve plugged up. Tractor hydraulics are operating normal.
Now, I have a new solenoid but cannot remove internal piece attached in the block.
How do you remove it? I also would like to know how to remove the valve for cleaning since I can't find it or know what I am looking at. Do you need to remove the entire block to remove valve? Looks like a big job to remove block.
Dealership is 3 weeks behind so that's not an option. I'm losing money when I am not cutting.
Thanks for your help!
 

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JD 455, 4610, 4052R, and 6120E
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The service manual tells you to remove the coil nut, then the coil, then simply says "Remove solenoid body from PTO valve block" without telling you how.

It appears from the pictures both in the service manual and on the JD parts website that the solenoid body might be threaded and screwed into the valve block. It has a gasket between the solenoid body and the valve block, so surely it is threaded and screwed into the block.

Do you see some flats on the solenoid body that might allow you to unscrew it with a wrench?
 

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Discussion Starter · #3 ·
Thank you sir,
That is about all the info I have found also. The flats are visible, but they are recessed into the block so that a wrench or socket will not grab. Genius design. What the hell were they thinking with that. I just got the threaded part to break loose from the block. It took a 1 ft pipe wrench multiple tries to get it loose. Big vice grips would only spin on the shaft. I'm not sure how I will get new one tight. I was about to remove the wheel, fender etc to get to the scv to remove that so I could remove pto block. I did remove the filter, housing, return pipe, mid mount hyd pipes to be able to move tools under there.
There was no trash in the valve so I guess that is good. I certainly do not want to do this again.
If anyone has more info please add it to this post to help the next guy.
 

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The PTO Valve performs many functions including the following:
  1. Includes a PTO Solenoid valve which moves a spool to determine whether hydraulic pressure is applied to the PTO Clutch and PTO Brake to both engage the clutch to spin the PTO shaft and release the PTO Brake so it may spin, or release this pressure to disengage the PTO Clutch and apply the PTO Brake.
  2. Includes a PTO Clutch/Brake pressure relief valve to set the available hydraulic pressure to 216 psi +/- 10%
  3. Includes a PTO lubrication pressure relief valve to set lubrication pressure to 5.7 psi +/- 10%
While the PTO Solenoid Valve plays an important role in the PTO Valve, there are many other internal parts and seals which, if they become contaminated with something like teflon tape or debris, could fail to perform their function and prevent the PTO from working. The service manual has an entire section devoted to guidance on disassembly, cleaning, and o-ring replacement for the PTO valve body.

There are 2 pressure test ports on the tractor which allow you to A) verify that when the PTO is engaged that 216 psi +/- 10% of pressure is applied to the PTO Clutch and Brake and B) verify that 5.7 psi +/- 10% of lubrication pressure is always applied to the PTO clutch, brake, and other PTO mechanisms to keep them from being damaged.

If replacing the PTO Solenoid Valve doesn't fix the problem, I would probably next perform the 2 pressure tests. It is likely that the pressure being supplied to the PTO Clutch/Brake is insufficient to fully engage the PTO clutch. This could be caused by valving problems in the PTO valve, or by something like a dirty seat in the PTO Clutch//Brake pressure relief valve that is preventing adequate pressure to be applied by the PTO valve.

It is also possible that the PTO clutch is worn out and requires replacement of the clutch plates, but hopefully this is not the case since this maintenance activity requires splitting the tractor.
 

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Discussion Starter · #5 ·
Thanks for the info. 1200 hours on the machine. Probably half of that is pto time. Oil and filter are 130 hours and 1 year old. The new pto solenoid did not cure the problem. Battery voltage to the end of the pto harness. Zero debris on the valve behind solenoid. The valve has some notches and cut outs on it, but there were no detents indicating a certain position to install it? There was some debris on the main screen. Dealer service manager thought is was brake material but not enough to worry about.
It looks like next step is find the test ports?
 

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That is too bad that replacing the PTO solenoid valve did not solve the problem. The solenoid valve screws in until it is tight, and just moves a rod in/out that is inserted into the end of the solenoid valve, so there should not be any certain position to install it in.

The technical manual is expensive, but now might be a good time to visit the John Deere Technical Information Store and purchase the download copy for your tractor. There are 2 different serial number ranges for the U.S. 4320.

At least for my 4610, the manual says you will need to remove the seat and close in cover under the seat to expose the PTO solenoid valve block. The 216 psi test port A is on the top of the solenoid valve block, and the 5.7 psi lubrication pressure test port is on the side.

Here is a picture of the location of the top mounted "A" test port (probably the most important to test since it is the 216 psi pressure applied to the piston that presses the PTO clutch plates together to make the PTO shaft spin).

782175
 

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Discussion Starter · #7 ·
With partial engagement of pto, I'm betting on debris in the valve not allowing it to operate. I think I will remove the valve body and take that to local pump shop for a rebuild if I can just remove tire and fender to access it completely. I have repaired a broken pin on scv before, so I have at least been in there. That seat pan removal looks like a 2-6 day job. I think I'll look into the repair manual. The dealer is expensive and always a month behind.
Oh yeah, I discovered my alternator is out also. If it ain't the peanut butter, it's the jelly. At least I made several benjis friday doing loader work!
 

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Discussion Starter · #8 ·
Need help. I had the pto and scv valves cleaned and rebuilt by a local guru. Upon re-assembly, I have a couple new noises and almost no hydraulic flow. Loosening the pressure lines on the bottom of the pump only get a dribble out. Ounces per minute instead of gallons per minute. It should be spraying oil everywhere. It also is loading the engine plus a metal on metal sound from the rear of the tractor at idle and gets much louder at 1200 rpm.
Pump dude said it sounds like a suction problem since no flow out of pump that was working ok 2 weeks ago. I changed an oring on the suction tube side in the oil filter housing. A damaged oring would only slow flow, not stop it almost completely. The pto comes on with the switch, but I don't know if it is locking properly since I can't hook mower up.
The engine lugging has me puzzled? I don't know if pressure relief valve is on or not?
Any ideas? I make a living with this tractor and need to get it running without throwing excess money at it.
Thank you!
 

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Discussion Starter · #9 ·
Today, I loosened pressure lines and use air hose to pump some air into dipstick tube until oil ran out of pressure lines to prime system. Started tractor, still lugging but no difference in 3 pt lift. Still barely going up to halfway point.
Any other ideas?
 

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I’m afraid I can’t offer help on you hydraulic issues, only condolences.
I had the same PTO issue with my 4320 when I bought it and it was debris in the valves. Then I had the opposite issue, the PTO wouldn’t turn off. Again, debris in the valve. I don’t know or understand where the debris is coming from as I had changed the oil and filter during the first repair.
 
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