99-01 Jinma 254 3 point wont lift

[Affordable]

There is a small set screw for a straight head screwdriver

Tommy
Affordable Tractor Sales

 

[piper184]

That linkage arm not being connected probably contributed to your situation.
It is good to know that you can access the cylinder by removing the front and rear covers. I wasn't sure it would give enough room to work inside.
Here is a picture of my adjusting knob and set-screw. 2006 284

 

[Cherryman]

I removed the back plate and saw the piston rod hanging with a black o-ring hanging around it (pic 1). The piston was all the way to the front and could not be retrevied. I removed the lift box, a horrible design with a bottom cover what would keep hydraylic fluid from leaking into the gear box. With the lift box removed I unbolted the front cap and the cylinder was removed after pushing out some left over fluid the piston suction was released and piston slid out. I also found both of the nylon washer wipers were in pieces shattered everywhere. The o-ring that was hanging around the piston rod was in one piece but it was split down the middle leaving a 1/8 " thick o-ring where its usually .25 " thick. Its wonder the 3pt worked at all. I also found what was left of the dipstick. One more observation if the piston rod is not connected to the piston, if the pressure goes slack the piston rod ball becomes unseated and guides itselfs back into the piston center ? The last pic shows two dings where it looks like the rod has smashed into it while self guiding its way back to the piston?

 

[piper184]

Good thing you got in there to do some TLC. I think your assessment of the dings in the piston are correct. IF the lever was in the down position and the 3pt had lowered itself normally the piston would be at the bottom of the travel. Then if something (or someone) manually picked up the lift arms or drove the tractor with something on the 3pt in such a manor as to cause it to "float" upwards that could cause the push rod to come off of the piston. That is the only scenario where I can see the piston and the push rod separating. Normally just the weight of the arms will keep them connected. If the piston has no other damage, I would go ahead and re-seal it and move on. The dings don't look like they would effect the travel or the seal of the piston to the cylinder. A pain the wazzoo, but good work.

 

[Cherryman]

When I rebuild it Ill index the arm position to piston location and use the linkage correctly. By the
way do you know a good torque setting to use on the lift box? The underside cover is the most important one. I'll use threadlocker but the removed bolts were not that tight when removed? Thks Rob

 

[piper184]

There should be a button on the inside of the rear cover that is supposed to prevent the lift arms from going up too far, thus keeping the piston in the cylinder. Since you have it upside down and apart, you should be able to check that before re-assembly. As for torque, I don't have the info in front of me, but there are charts that show "standard" torque values for different sizes of bolts and thread types. I use these when there is not value listed in the manual. Do a quick web search and I am sure you can find one. If not, let me know and I can scan the one I have and post a picture of it.
Sounds like you have a good handle on things.

 

[Cherryman]

There should be a button on the inside of the rear cover that is supposed to prevent the lift arms from going up too far, thus keeping the piston in the cylinder. Since you have it upside down and apart, you should be able to check that before re-assembly. As for torque, I don't have the info in front of me, but there are charts that show "standard" torque values for different sizes of bolts and thread types. I use these when there is not value listed in the manual. Do a quick web search and I am sure you can find one. If not, let me know and I can scan the one I have and post a picture of it.
Sounds like you have a good handle on things.

Thks Piper184 and QSF for your help. The rubber bumper is attached to the rear cover and Im guessing with a proper pressure in the cylinder the piston rod ball will remain seated in the piston.

 

[Cherryman]

Thks Piper184 and QSF for your help. The rubber bumper is attached to the rear cover and Im guessing with a proper pressure in the cylinder the piston rod ball will remain seated in the piston.

I was thinking of changing the gear oil since the lift box is off. What should I use 80 - 90 weight?

 

[Cherryman]

While rebuilding the lift box I cleaned the cylinder and piston added the o-ring and wiper washers. Added a little fluid to the piston and inserted into the cylinder easliy up to the middle o-ring. Thats where its stuck should I press it in ?

 

[piper184]

I use 80W-90 in all the manual gear boxes of the 284. Different weight hydraulic fluid for different seasons, sometimes even ATF in the winter.

As for the stuck o-ring, I'm trying to imagine what you are describing. Any chance you can post a picture?