1970 JD 4320 weak hydraulics

Anonymous-0

Well-known Member
Weak hydraulics when using loader. Fluid level is good and filter is new but hydraulics are weak. How or where do I check the pickup tube screen to see if it's clean? No chatter when I start tractor so it doesn't seem to be starving for oil from back pump. So does that eliminate possible pickup tube issue? Have heard about pressure relief or bypass valve as possibility. Is that under dash or where? Can it be tested? Any help or troubleshooting checklist is appreciated. Thanks
 
First thing to do is check the stand by pressure by putting a gauge in one of the remotes and activating it, you should have 2250psi, if not you can turn the stroke valve screw in a couple turns on the under side of the pump till the pressure is right,,how do you have the loader plumbed in??
 
I recommend checking/cleaning sump screen and possibly checking filter(parts key #17) in frt hyd pump. If it were my tractor with a frt loader I'd set the stand-by pressure 100#s higher to 2350 psi. Parts key #37 is the screw Tim referred to for adjusting the stand-by pressure.
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The loader is plumbed directly into the rear hydraulic outlets and I use the console levers for control. No auxilary valve is used.
 

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