John Deere 4020 hydraulic issue

John Deere 4020 hydraulic issue Problems

Just to make sure I’m not missing something. Our 1968 4020 seems to lose prime of the hydraulic system after being idle for a while. I don’t see any major leaks and no oil leaks. A couple of years ago it started to happen that after starting you had to wait 10-15 seconds before anything could be done with the loader. Now it can take a full minute before any hydraulic system works.
Does this mean the bomb is on its last legs or is there something else it could be missing?

John Deere 4020 hydraulic system

Here’s a service bulletin for adding a check valve to eliminate hydraulic oil drain causing this problem you mentioned.

Why not check the pressure potential of the pump using a hydraulic gauge and see if the relief is properly adjusted and releasing at the set pressure?
Check all the fittings and the suction tube, you may have a suction leak.
Have you looked in the tank to see if there are small bubbles.

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