Hydraulic leak while running on JD 4020

[Danny Barnett]

I have a '65 4020 that leaks down on the 3 pt. hitch while using implements. Is this the rockshaft control valve and what will it take to stop the leaking down?

 

[Tx Jim]

Leak down could be control valves leaking from not seating,piston seal or thermal relief valve leaking. Easiest thing to check is the piston seal by removing the cover in photo and replacing piston seal.