4020 3-point no lift

[Client]

My 1968 JD4020 three point fails to lift. Power steering works fine. Changed canister filter and cleaned screen filter. Earlier this year I could drag the bushhog around in the field and eventually it would lift but not hold the setting very long. I need some experienced advice! Thanks

 

[Tx Jim]

Welcome to this forum
Is L/D lever located under seat in position "D"? If not it needs to be put in that position. Is rockshaft control cable free to move allowing control of 3pt control valves? Next I recommend acquiring a 5000 psi hyd gauge & checking hyd stand-by pressure. Stand-by pressure should be 2250-2350psi.

 

[Client]

Tx Jim, Appreciate your input. Will ck out the "D" position and cable movement tomorrow.

 

[matthies]

Maybe take off the tinwork under the right hand side of the seat to see is the arm is moving on the valve housing. 5 bolts and the filler cap for the rearend.

 

[Paul_IN]

Have you used the hydraulic remote(s) with a cylinder? If this does not work quick and strong then it could point to the priority valve having an issue. The priority valve should cause rock shaft and remote hydraulics to not function correctly, but steering and brakes can still work, if system pressure can not hold about 1700 psi. This is why Tx Jim suggested you put a gauge in the rear hydraulic connection as it’s the easiest/quickest way to check stand by pressure.
The priority valve would not cause of the symptom of 3pt failing to hold very long when it did raise.
Let us know what you find.

 

[Client]

Will do! Thx Paul