JD 4020 Priority valve

[magpiene]

Where is a good place to get a priority valve for a 4020. Or should I try to rebuild mine. Works fine , but rattles terrible.

 

[David G]

Are you sure pump is working OK?

 

[Bob]

There's nothing in there but a plunger and a spring. Unless the spring has broken, all should be well.

I agree with the other reply, you probably have main pump issues, or it's cavitating from lack of oil from the transmission pump through the filter, etc..

 

[David G]

I should say pumps.

 

[Tx Jim]

I agree with the other posters. I'd suggest to check stand-by pressure. It should be 2250 psi.

 

[Jackless@1234567]

1965 j d 4020 priority valve hammering noise , louder than engine noise. Took all internal springs ,shims, rod , ECT out of priority vale and started tractor and no noise ? have changed pump, filter, cleaned screen, fluid, even changed number of shims in the priority valve plus put new springs in. No one seems to have a clue whats wrong. No old timers around anymore. John deere mechanic said nothing wrong, but there is a distinct loud noise that is not normal. Any suggestions would be great. Thanks !!

 

[Mark-Ia]

Bushings in the drive coupler between the engine and pump will make a loud hammer noise.

 

[used red MN]

Edit: Oops, sorry my reply was not relevant.

 

[Tx Jim]

1965 j d 4020 priority valve hammering noise , louder than engine noise. Took all internal springs ,shims, rod , ECT out of priority vale and started tractor and no noise ? have changed pump, filter, cleaned screen, fluid, even changed number of shims in the priority valve plus put new springs in. No one seems to have a clue whats wrong. No old timers around anymore. John deere mechanic said nothing wrong, but there is a distinct loud noise that is not normal. Any suggestions would be great. Thanks !!

My guess is priority valve housing or spool is faulty. I suggest to replace both with known good used similar components.

 

[Jackless@1234567]

i have replaced priority valve with a used one , no change what spool would you be talking about ?.. I have ordered some flare cap and plugs to start isolating my hydraulic lines leaving the priority valve and see which one stops the plunger valve to stop hammering in priority valve and go from there.

 

[wore out]

i have replaced priority valve with a used one , no change what spool would you be talking about ?.. I have ordered some flare cap and plugs to start isolating my hydraulic lines leaving the priority valve and see which one stops the plunger valve to stop hammering in priority valve and go from there.

Likely, you have a hydraulic pump issue such as a failed "exhaust valve" on one of the pistons.

"Flowrating" the pump should show reduced output if this is the case.

 

[caterpillar guy]

I'm with checking those bushings on the pump coupler they will make a racket when worn out. will also cause pump problems and at about 800-1000 for a new used or reman pump they are cheap at probably a 100 for the set of 4.