Pressure relief valve malfunction?

   / Pressure relief valve malfunction? #1  

adrenolion

New member
Joined
Jul 22, 2025
Messages
2
Tractor
Ford 1720
Hey all!
I have an older ford 1720 with a liberty kpx-6/LW-6 that I'm trying to trouble shoot.
It started heating the hydraulic fluid with use and the fluid would look aerated after awhile. Then it basically stopped working all together.
I'm pretty sure that the pto pump is still good, after putting a shutoff in-line I can run it down and almost stall the engine.
So, I'm thinking pressure relief valve? I can't find a replacement for it or I would just replace and eliminate that possibility and move on to the next thing. (Valve body?)
Any and all help would be greatly appreciated! Parts numbers, exploded views, ideas, eliminating processes?
Thanks in advance
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   / Pressure relief valve malfunction?
  • Thread Starter
#2  
Pressure relief valve
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   / Pressure relief valve malfunction? #3  
Relief valves rarely fail closed they typically fail open.

Where did you have the shut off valve in relation to the relief valve when doing your test?

With shut off valve fully open What pressure do you see with all the valves in spring loaded home position?
What pressure do you see when operating a function and when that function dead heads?
 

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