Hydraulics moving without touching controls

[Mearntain]

1970 Ford 2000 3 Cyl Gas

The other week I went to replace the pto seal on the tractor, and something came up and wasn't able to finish it. The farthest I got was draining the rear oil and refilling it. The old oil seemed to have a bit of water contamination in it. (Not sure if this bit of background is relevant or not, but thought I'd include it)

Prior to changing the hyd oil, everything worked fine with the hydraulics. Now when I went to hook the bush hog up, I noticed the arms were sitting about 3 inches too high to connect up to it. The hyd position lever was in the fully lowered position and nothing I tried could get it to gp all the way back down. After cutting the tractor off, it eventually blead to fully lowered a few hours later. Started back up, it instantly raised back up a couple inches.

What could be causing this and where should I start to look? Is this possibly something with the draft control causing this issue ? I still find it kinda odd how this problem instantly started and didn't come in gradually. Thanks in advance for any input yall may have.

 

[Texasmark]

Are you in Draft or Position Control? As I recall in Position Control the lever on the right side of the hyd part of the housing, below the seat and Position Control is pointing down...vertically. What fluid did you use? Other than the lever, makes no sense if all you did was to change the fluid. If nothing else, put an implement on the 3 pt and run it up and down a dozen or so times in the Position Control position.

 

[Mearntain]

I don't remember the brand used, but I got the proper universal hydraulic/Trans tractor oil from tractor supply. Currently the draft control levers pointing straight up in a vertical position.

 

[Texasmark]

Well I just went out and looked at my 63 4 cyl 2000 and it's straight forward, corresponding to markings on the hyd casting. ON my '65 3000, which your 2000 is more like than the old designed 2000 it's straight up like you say your's is.

Okay. Where is it supposed to be before it starts moving? Is it supposed to be up due to your position of the position control lever? If so, then my best guess is that the pump is working bubbles out of the system and it takes time for it to get the ones affecting the positon and allowing for adequate pressure to lift the arms.

In that case, I'd put a load on the 3 pt and cycle the position lever all the way up and down couple of dozen times to work the air out. Other that the above, I can't help. Sorry.

 

[Soundguy]

System should purge air out near instantly, its a constant flow unloader system.

Recheck draft setting.

If arms slowly rise and continue to rise, post back with that.

If no,try partially applying draft and observe arms

 

[Mearntain]

Sounds good, I'l get back out it to it sometime tomorrow. I picked up a plow today that I need to unload so I'm gonna need to bring the tractor up to pick that up anyways. I'll post back here with what happens.

 

[Texasmark]

System should purge air out near instantly, its a constant flow unloader system.

Recheck draft setting.

If arms slowly rise and continue to rise, post back with that.

If no,try partially applying draft and observe arms

Hi again, Guy,

Walking through what you said, if I understand you correctly and this would help Mearntain, unlike a dead end FEL cylinder system, the open center Ford system is leaning on the "unloader valve" as long as the engine is running and the fluid flow isn't being diverted to do some other form of work. That would help to vent any bubbles in the system developing by the fluid change. I don't have my flow diagrams handy to see the relationship of the flow to the unloader and the lift piston, but I do remember moving my position control up and down numerous times in the past to clear up unexpected performance variations of my 3 pts on occasion. Or maybe I'm remembering one of my JD closed system tractors, or a FEL.

 

[Soundguy]

backpressure valve develops about 40 psi, and unless diverted the system dups to sump via the unloader.

first time you pressureize the 3pt, it will blow the air out the oring seals on the lift piston..

 

[Texasmark]

backpressure valve develops about 40 psi, and unless diverted the system dups to sump via the unloader.

first time you pressureize the 3pt, it will blow the air out the oring seals on the lift piston..

Thanks

 

[Mearntain]

Sorry for the late reply, it's just been one crazy long week. I was out there tonight and it seems to be fine now and not doing it anymore. I didn't change or mess with anything other than try to plow a little bit the other day, but hopefully it won't be coming back. Thanks everyone for the input and tips