Green Tractor Talk banner

1 - 6 of 6 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter #1
I'm New to the forum and sincerely appreciate any advice no matter how simple or basic it might seem.
I have a 1970 JD 4020 with 5000 Original Hours on it. I am the 2nd Owner. First Owner Pulled a 7ft Bush Hog and a 7ft blade on His chicken Farm so it's never Pulled a disc or set of plows or worked very hard. He sold his Farm and equipment and Retired. When I bought it, I noticed that the Lift Arms would raise Fine and seemed to stay raised until the engine was stopped. They would Slowly (over an hour or so) Leak Down. Starting the engine with the lever up wouldn't raise the arms, initially. I put 10 gallons of hydraulic fluid in it since I wasn't showing any on the dipstick. Now they still leak Down but will Raise without touching the lift lever. I don't See any major hydraulic fluid leaks After parking it on the concrete for several hours. (There is some oozing around the right side hydraulic coupler). The Power steering, transmission etc work Fine. I realize this is probably a common, simple question to Most folks on this site So Any Advice would be Greatly Appreciated ! Thank you
 

·
Registered
Joined
·
982 Posts
Sounds like you are leaking oil internally. May be the piston oring. That is pretty easy to change. The control valves may need reseating and/or adjusting. Or the thermal relief valve may be bad. Does oil seem to get extra hot when running?
 

·
Registered
Joined
·
972 Posts
I know NOTHING about a 4020, so let me just throw some "logic" out there!
I've got to think you've got a "neutral" position on the 3-pt control lever where the arms don't raise or lower. Have you tried shutting down tractor in this position?

My thinking is that in the raise position. you have constant pump pressure to one side (raise side) of your lift mechanism. Shutting down in "raise", the pressure is gone and the weight of the arms pushes the oil in the mechanism back through the valve, through the pump, and into the reservoir. Bob
 
  • Like
Reactions: BaconDoc

·
Registered
Joined
·
2,090 Posts
I agree with jd110. 1st thing I'd recommend is R&R of rockshaft piston seal. This seal can be accessed after 3 pt hitch has been lowered by removing cap that has 3 pt centerlink transport hook attached to it. If new piston seal doesn't stop 3 pt from settling then I would suggest to check 3 pt valves operating clearance by removing a plug in rockshaft control valve housing.
 

·
Registered
Joined
·
14 Posts
Discussion Starter #5
Thank y'all !! I am going to take a look at the Piston Seal First and go from there. I'll let y'all know if that's what's causing the Problem. If it's ok, I'll Move on to the Valve clearence.
jD110, no Sir the Oil doesn't seem to get extra hot after a couple of hours of running it.
rwmeyer, that's something that I haven't thought about. I appreciate you jogging My Old Brain to think outside of the Box.
 

·
Registered
Joined
·
2,090 Posts
rwmeyer
Basically if 4020 3 pt control valves are adjusted correctly with the correct amount of clearances the "neutral position" you referred to will be at any position the control lever is positioned in the quadrant.
 
1 - 6 of 6 Posts
Top