I'm feeling lucking! 1987 NH Ford 3910 with no hydraulic pressure for loader/backhoe.

[JL Sargent]

I have had this tractor for 30 years. I added a Koyker front end loader 25 years ago and added a Case 125 backhoe to it 15 years ago. This is an open center system. I turned this farm tractor into a backhoe is what I did. All has worked well until this week. While using the front end loader to load sand in a top dresser for my son's high school football field, the tractor lost the ability to do hydraulic work. It got weaker and weaker over 4 or 5 loads and eventually would not do a thing. I then tried operating the backhoe and it wouldn't do squat either. So I'm thinking hydraulic pump at this point.

This tractor has a transmission mounted hydraulic gear pump. Took me about an hour to get that pulled. I expected to find a broken pump, but no, it actually feels tight and looks good. Hmmm, what to check next? I then drain the fluid and remove the hydraulic oil filter. I cut that in half and only found a few small pieces of cylinder gland seals (I have rebuilt at least a 1/2 doz on this thing) so it is not stopped up and no metal or sludge in filter. I disassembled the pressure relief valve on the front end loader and inspected it. All seems ok there. I Poured all the hydraulic fluid through a strainer and found nothing of concern. No water in system at all. Not sure where to go from here. I have the factory service manual for this series machine, but it's not too good to be honest. The tractor itself has to have a pressure relief valve somewhere, but where is it? Any help appreciated!

 

[DLTTrekkers]

Photo of your FEL controle valve wil help us to help you ?

 

[JL Sargent]

Photo of your FEL controle valve wil help us to help you ?

This is the valve. Its a Pace 7040. Koyker still sells this one. This valve is the first thing the hydraulic power goes to. Out of the remote power block under the tractor seat to this valve on loader and then from power beyond port on this valve to the backhoe attachment and then back to tractor housing/tank. I wonder if this valve is simply worn out and returning fluid to tank anytime pressure is in the system? I mention this because the valve is plumbing power beyond and there is a return to tank on the valve too, so it's possible.

 

[DLTTrekkers]

This is your reliefe valve.
I think your pump is on its way uot. TEF and digger at the back is a lot of hydraulic work !

 

[JL Sargent]

I did take that relief valve apart. It looked ok. I suspect the FEL valve is just worn out and diverting pressure back to tank. Isolating the backhoe to the hydraulic system would take that valve out of the equation. If it works properly in that configuration, I know what to do.