John Deere 440 A lost hydraulics after blowing hose

earache · April 28, 2019, 07:17:14 AM

I am running a 1970 (ish) John Deere 440 A cable skidder. Everything was working fine. Had a hydraulic leak under the machine. I pulled the belly pan and found the hydraulic fitting on the left side (as your sitting on it) steer cylinder was leaking. I made a wrench and tightened that. Left the pan off to verify the repair (BIG mistake) .Took it for a turn and ran a stick up through the belly and it broke a fitting off .The fitting that broke was the three way fitting sticking out of the side of the brake valve .I removed that, had it repaired, and reinstalled it. Checked fluid and fired it up . Hydraulics were very jerky .I took it back to the landing and parked it. Rechecked fluid (it was fine). Reinstalled belly pan, and left for the day. Next morning (yesterday) I fire it up, let it warm up for twenty minutes, take off. Hydraulic functions still very jerky. After about five minutes, I lost all hydraulic functions.
With transmission filler cap out, can look down in the transmission and see that the hydraulic oil isn't moving. It isn't being pumped.
Tried bleeding at top of steer motor , to no avail. (No fluid comes out, but did at first). Cracked line loose on right side (as your standing in front of and looking at machine) of piston pump, no fluid coming from there. I'm being told that this hydraulic line feeds the Piston pump oil from a gear pump inside the transmission. I drained oil and removed the tube screen filter inside the rear of the transmission. It looked good. While the oil was out, I replaced the large canister style filter on the side of the transmission.
Put filter back in, refill transmission, run it, same thing.
Anyone have any ideas as to what (else) to check?

TeaW · April 28, 2019, 07:29:54 AM

The pickup line for the gear pump in the transmission fell off on me once.

tacks Y · April 28, 2019, 08:52:56 AM

Like Teaw said. Which means removing rear brake cover. Not to bad a job. Maybe someone else will come up with other ideas. Seems odd this would happen at the same time as other problems. What does the 3 way fitting do? Any chance it is not back right?

Ford_man · April 28, 2019, 09:06:31 AM

I had a JD 4010 farm tractor that did the same thing. there is a small screen filter up front by or on the pump. It under a hex cap it takes a 1.125 in wrench to take out. it is about 1 in dia and about 3 or4 in long. PS this is coming from memory of 40 + yrs ago.
good luck

earache · April 28, 2019, 09:27:28 AM

@TeaW - how do I check that?

@tacks Y - this fitting is a tee. It sticks out of the side of the brake valve. There is a hose from the steering valve, a hose to the diff lock valve, and then thus fitting screws onto the side of the brake valve.
I took it back off yesterday morning, blew through it and looked through it.

@Ford_man - I pulled the screen filter and checked it. It looked good.