1365 - removing stuck pilot valve on hydraulic lift

fperron_kt88

New User
Hello all, second post on the same topic: short version here...

Any tips on how to remove the pilot valve on the hydraulic lift? That's the one on top of the head unit (under the brass cap screw). Lift gradually quit working.

The pilot valve rotates when applying hand force with a screw driver. The rest of the unit dismantled fine.
 
You might have to wait for Mitch Poindexter or Traditional Farmer to come along on that question. I will tell you this,the 3 pt on mine got weak this spring. I could go out and move round bales with it and after 25-30 bales,it would start giving out until it wouldn't even raise with nothing on it. I put a new pump on it and that took care of it.
 
Thanks for the replies.

I have the shop manual.

Did not measure the pressure at the input, but the failure on the lift was gradual. It went from lifting the nose of the tractor with the winch and big trees to nothing at all. At the same time, it continued to lift the haybine 479 with no performance change perceptible...

So, performance is the same on the aux, while the lift no longer twitches... and the pump was rebuilt in 2011.

Hope this helps...
 
..."At the same time, it continued to lift the haybine 479 with no performance change perceptible..."

I meant the aux continued to lift the Haybine 479 with no change...
 
I unfortunately don't have a pressure gauge to read within the 2000-3000psi range... Could ask Santa, lives nearby I'm told ;-) ...

In terms of hot/cold performance, I can assert that the aux hydraulics (thus the hydraulic oil pump) is functioning with equal performance on heavy objects (1 000lbs haybine head) at the moment of starting and after 4 hours of mowing. Pump pressure reading would definitely eliminate the pump question, I agree...

As a wildcard, I could swap the entire hydraulic lift unit, as I have another 1365 standing by and in top condition. Swapping the hydraulic lifts would clearly eliminate the pump as a potential culprit, as all is working fine on the other tractor... Swapping the pump could be done as well. Now that I think of it, the latter is probably easier ;-)

However, the head unit is already disassembled, except for the pilot valve that remains stuck in its bore hole, and I most certainly will have to finish disassembly and proceed to decontaminate anyways... Any idea on how to remove it from there?

I understand that this valve is meant to be driven by pressure, thus it could be hard to move by hand. It just seems odd that the tolerances would have been designed so tight in there, especially as the seal (seat?) is at the bottom end, not on the axial mating surfaces (that *has* to be a slide fit in oil).

So, I can certainly fork the job temporarily by swapping the pumps/lifts to eliminate the pump or figure a way to measure that pressure. In the meantime, both my intuition and recent experience with the aux tell me that the pump is working and the pilot is fishy on the lift itself. Plus the head unit is on my bench...

Is it normal that the pilot be this tight?
Any trick on how can to remove it to give it a good clean-up?

Thanks for the help and the patience...
 
If your aux continues to lift your implement just fine, then your hydraulic pump is fine, as you have pointed out. I know you said you think your copper sealing washers on the relief valve are fine, however, pull and check the 3 point relief valve and make sure it isn’t stuck open by debris. Light air pressure applied to the opposite side of the valve will allow you to remove it.

The system is simple, if you have hydraulic pressure, which you seem to, then there are only 3 possible reasons your lift won’t raise 1) relief valve bypass, 2) spool bypass, 3) hole in lift piston or piston seal failed.
 
Ah! Ok, thanks!

I will definitely check the relief valve for the copper seal. However, I already swapped the relief valve with the other tractor's with the same result.

As for 3) I can also assert that the internal piston seal is fine. The piston/sleeve unit was easily pulled out of the unit and tested fine in looks and slide fit tightness. The head seal was also fine (visual check only for rubber integrity and head condition, as there could be bypass sidewise to another chamber, but certainly no external oil leak of any sort...). So looks good there for now.

So 1) or 2) remain...

Progress! Thanks!

Ha ha moment: perhaps I can open the brass cap screw on the working tractor and test the movement of the pilot spool there? Will only get to it past 10PM tonight, but I think its a no brainer to check that now...
 
Assume you have already checked this, but if you have the head unit on the bench, make sure the check ball is seating properly. It’s the little ball on the piston side of the head that is covered up by a little rectangular piece of metal that is threaded into the head. It’s usually peened into place, so it’s not very serviceable. There should be a spring between the little piece of metal and the ball.

I think I have a head unit on the bench at home, I should be able to take some pics for you if it will help.
 
Ok, will double check the ball valve as well. The spring is definitely visible and the ball too. Did not want to break the tab on the screw (so little meat on there...) so the seat has not been checked yet...
 
use a short piece of heater hose, put it over the check ball and blow into the hose. The ball is either seating or it isn’t, and this will answer that question without fiddling with that little tab(read more chance of breaking something here that is most likely not the problem anyway)
 
We sold a man anew 1265 and after the first day or 2 it steered hard!. My employer the customer and the John Deere dealer were all in the same card club. I was told to solve the problem before the card club met! I made up a fitting to verify that my pressure was low. Took the relief valve apart and found a metal shaving holding the relieve valve open. I cleaned the spool and put it back together. It worked good. You may want to check if these check balls are all seating properly while you have the unit and check the pressure so you know if it meets specifications.
 
Looked at the hydraulic unit I have at home this morning. See the attached photo. What I failed to mention last night was that you can remove the pilot valve by threading a bolt into the top of it and pulling it out. The pilot valve body has a threaded hole in it for removal. Sorry for the omition.
6569.jpg
 
Haaa!!! This is it!!! I did not remove the oil in there and missed the threads!!! :oops:

Great! Any idea what size bolt it is? M12x1,25?

Is the pilot valve very tight in there in your unit?
 

And I will certainly want to check for pressure as soon as I have the thing cleaned-up and reassembled. Thanks for the anecdote!
 
Bingo!

I found a screw (more like an M6) and pulled the pilot out. Guess what: metal speck on the valve seat down below. Some contamination on the walls that made it sticky. You can see a fair amount of scoring and marring on the valve body... Not bad for a tractor about my age. The pilot will go back in there for another few decades... Did not take a photo of the seat, but it looks good. Will decide later if I want to lap-it a bit or not (any advice on this? I would do it like for a regular head valve with minimal amount of paste and rotation action)

Here is the pilot body:
view


It is now moving smoothly, just like everything else, with the simple action of a small magnet and after a simple clean-up/re-lube.

Here is the test with the magnet: much better now!
view


This is very good news, I believe ;-)

Thanks to all for the help and support!

Time for decontamination and rebuild. Fingers crossed...
 
For completeness: all is well, the tractor is fixed! It was a metal speck preventing the pilot valve's proper sealing action and general contamination that was preventing proper movement of said pilot valve...

Had to ditch the gaskets that were sourced for the job: very poor fit. Made them with generic paper and tack-it red stuff...

Replaced two o-rings and the plastic backing coil on the piston while in there. The main o-ring on the cylinder needed a weird plastic band to stay on while reassembling: nothing special, but a tad expensive at 23$CAD...

Thanks *a lot* for the help!

Now, let there be snow!
 

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