Kubota L3940 All the Sudden Won't Move and Hydraulics Won't Work

webmonk · Jun 1, 2021

I was mowing the back side of our pond dam. I back down and drive back up. I have done this many times before. After a few times today I was driving back up and all the sudden my forward movement stopped. I put my foot on the brake and tried a few times to drive up, making sure that it was in gear, but every time I let off the brake I would start rolling backwards. I tried the hydraulics (loader and PTO mower) and neither would raise up. I turned it off and started it again hoping that would reset something, but it didn't. After several attempts in different gears and settings (in case I bumped something) I gave up.

Does anyone have any idea of the likely cause and solution?

Rebeldad1 · Jun 1, 2021

basic stuff to start. check hydraulic fluid incase something like a hose or fitting broke. check fan belts incase the pump is driven by belts.

ptsg · Jun 1, 2021

It sure looks like you lost all of your fluid. Definitely check your fluid, then take a look under the tractor. Pretty sure a stick or something pierced an hole of the hydraulic filter or pulled another line apart.

If it's HST, that would explaining it rolling when you release the brake as there is no fluid on the pump nor motor, it will just free spin. A very dangerous aspect of the HST that's is often overlooked. Specially if working on the steep hills.

Rebeldad1 · Jun 2, 2021

OP... where are you at with this?

webmonk · Jun 3, 2021

I noticed a large area (somewhere else) where some fluid had leaked where I had it parked. It wasn't a drip because it was a wide area, maybe like 3' x 3'. That was a bit disturbing.

At the advice of someone I tried adding more hydraulic fluid. I have no way of knowing what level it's at because it is still stuck on the hill and the dip stick and fill hole are both on the downhill side. I put in maybe 2-3 quarts. I was still unable to get it to move after adding more, but I was able to move the implements (although reluctantly).

I tried to tow it up about 15' to level ground so I could better diagnose things, but was unable to with my SUV. I have someone else with a tractor coming today to tow it up. Hopefully I'll know more by tonight.

ptsg · Jun 3, 2021

2 to 3 quarts is nothing on a tractor that lost most of the fluid, although, being on the hill, I'm sure there is still some in it. Accordingly to TractorData, that tractor takes a total of 11.4 gallons of fluid.

sea2summit · Jun 3, 2021

webmonk said:
I noticed a large area (somewhere else) where some fluid had leaked where I had it parked. It wasn't a drip because it was a wide area, maybe like 3' x 3'. That was a bit disturbing.

At the advice of someone I tried adding more hydraulic fluid. I have no way of knowing what level it's at because it is still stuck on the hill and the dip stick and fill hole are both on the downhill side. I put in maybe 2-3 quarts. I was still unable to get it to move after adding more, but I was able to move the implements (although reluctantly).

I tried to tow it up about 15' to level ground so I could better diagnose things, but was unable to with my SUV. I have someone else with a tractor coming today to tow it up. Hopefully I'll know more by tonight.

Do you see any in the sightglass or dipstick? If not I'd add until you do, if it dumped all the fluid I'm surprised it could even get pressure with only 2-3 quarts. Did you already check the plugs? Any other obvious signs of leaks?

Leejohn · Jun 3, 2021

After you get it on level ground or shop, on the right side at the firewall see if there is a short rubber hose on the pump inlet line, check for cracks or hole. Then check the little button under tractor at the bell housing and see if you have oil coming out. Then I would check the screen on the inlet in the trans and change filters.

jonsstihl · Jun 3, 2021

The grand L 40 series has no screen on the inlet pipe. the suction filter is the screen but definitely check the split pin plug on the bottom of the trans and the rubber coupling elbow on the inlet pipe to the hydraulic pump like leejohn said.

ning · Jun 3, 2021

webmonk said:
I noticed a large area (somewhere else) where some fluid had leaked where I had it parked. It wasn't a drip because it was a wide area, maybe like 3' x 3'. That was a bit disturbing.

At the advice of someone I tried adding more hydraulic fluid. I have no way of knowing what level it's at because it is still stuck on the hill and the dip stick and fill hole are both on the downhill side. I put in maybe 2-3 quarts. I was still unable to get it to move after adding more, but I was able to move the implements (although reluctantly).

I tried to tow it up about 15' to level ground so I could better diagnose things, but was unable to with my SUV. I have someone else with a tractor coming today to tow it up. Hopefully I'll know more by tonight.

Improvement with 2-3 quarts is promising.
I'd add gallons. Worst case is that it overflows out the fill neck; best case is it moves and then overflows.
Just how steep was that bank you're parked on?