John Deere 401c

[V86EAL]

I have a John Deere 401c tractor with front end loader that I was operating and all of sudden lost forward movement , the loader hydraulics and the power steering . I thought it was the front coupling on the front hydraulic pump ok . I have a new noise coming from that area . Checked out the coupling on the pump ok . I am able to go into forward and reverse and drive the tractor . Still no power steering and loader . I put a pressure guage and external relief value on the pressure side of the pump and have 150 psi which makes sense because that should be the pressure coming coming out the transmission pump to feed the front pump and forward and reverse. I am guessing something has happened internally in the front pump.Does anybody have any other Ideas ?

 

[Harvey H]

I would agree that you should concentrate on the front pump. You could check inlet pressure to the front pump just to make sure oil is getting there. Then make sure to check the the coupler splines are not stripped out and the input shaft is turning. The comment that you have a new noise coming from "up there" seems to be strike two for the pump. I've seen them fail internally where they just grind themselves to pieces inside. Removing the outlet line and checking for metal debris would confirm that.
If you end up changing out the pump do not disassemble it. That will void the core value. Also, when there is a major failure make sure to do a clean up procedure before you start up again with new oil and new filters every so often until everything is cleaned up. No sense recirculating a bunch of metal through a new or reman pump. Normally there is an inlet screen to the transmission pump that should be cleaned while the oil is out of the tractor.

 

[Tx Jim]

How long since hyd filters were changed & sump screen checked/cleaned? I'll 2nd closely inspecting frt pump coupler. It's possible stroke control valve has some debris lodged in it. If frt pump has a destroking screw you can try turning it in/out several times to try to dislodge any debris.