Lost Lift on Front Hydraulics and rear three point.

[Ester AK Kubota]

Hello everyone. I hope to get some help on where to start. I am in Alaska. I am sort of the local neighborhood mechanic. The neighbor has a small organic farm and an old B7100 $x$ Tractor. It is a manual transmission, with Loader and rear Box Blade/Tiller. The other day he was moving some snow and just lost all Hydraulic lift to the front loader and rear three point. There is just nothing. The rest of the tractor sounds and runs fine. I drained the transmission/hydraulic fluid and checked the lower screen. It was nice and clean with no metal. I can confirm that I have fluid flowing as I can see fluid flowing to the return line on top of the transmission just in from of the seat coming from the valve body for the loader when I move the lever. Is it a pressure relief valve stuck somewhere? I do have a factory service manual coming soon. Any help is appreciated.

 

[North Idaho Wolfman]

You can get the manual on Kubotabooks.com for free.
Is the loader running off the pump on the side of of the block?
If it is, you need to first check for good flow from the pump, if it doesn't have good flow it could be the drive to the pump failed.

 

[TheOldHokie]

Hello everyone. I hope to get some help on where to start. I am in Alaska. I am sort of the local neighborhood mechanic. The neighbor has a small organic farm and an old B7100 $x$ Tractor. It is a manual transmission, with Loader and rear Box Blade/Tiller. The other day he was moving some snow and just lost all Hydraulic lift to the front loader and rear three point. There is just nothing. The rest of the tractor sounds and runs fine. I drained the transmission/hydraulic fluid and checked the lower screen. It was nice and clean with no metal. I can confirm that I have fluid flowing as I can see fluid flowing to the return line on top of the transmission just in from of the seat coming from the valve body for the loader when I move the lever. Is it a pressure relief valve stuck somewhere? I do have a factory service manual coming soon. Any help is appreciated.

If you have return flow from the valve when a spool is shifted the pump is supplying oil to the valve. That oil can only come via two paths:

1. As return oil from a cylinder that is being extended or retracted. If the loader isn"t moving your flow is not taking thst path.
2. As over pressure relief oil coming from the inlet pressure relief in the loader valve. If thats the case and the loader and 3pt are totally inoperable the relief valve has probably failed or stuck open.

I suggest you test pressure as follows. Disconnect the power beyond hose from the power beyond port on the loader valve and connect a 3000 PSI hydraulic pressure gauge to the port. Start the tractor, raise RPM to 2000 RPM, and read pressure with all spools in neutral. If you are getting return flow at the transmission and the PB pressure is not 1600 PSI or greater the loader relief has failed.

Dan