Deere 4020 hydraulic issue

[JasG]

Just to make sure I'm not missing something. Our 1968 4020 seems to lose prime on the hydraulics after it has been sitting for a while. I don't see any major leaks and it's not losing oil. It started a couple years ago where after start up you would have to wait 10-15 seconds before any steering or you could do anything with the loader. Now it can take a full minute before any hydraulics will work.

Does this mean the pump is on it's last legs or is there something more I could be missing?

 

[Tx Jim]

There is a service bulletin to add a check valve to eliminate hyd oil drain back that causes this problem you mentioned.

 

[J_J]

Why not check the pressure potential of the pump by using a hyd gage and see if the relief is set right and relieving at the set pressure.

Check all your fittings and suction tube, you may have a suction leak.

Have you looked in the tank for small bubbles.

 

[Tx Jim]

Here's a website pertaining to your tractors hyd problem I learned about several yrs back from another tractor forum. Fixing JD 4020 hydraulic loss

 

[JasG]

Here's a website pertaining to your tractors hyd problem I learned about several yrs back from another tractor forum. Fixing JD 4020 hydraulic loss

Thank you for the idea. I did see that last night while searching for this problem, only ours if fine with the clutch pushed it, it's just while sitting with the engine off. It's worth looking into though. It seems to have good pressure and I know he had a dealer mechanic pressure test it last year. He didn't ask about the prime at the time though because it wasn't that bad.