Kubota L3901 PTO Lever Is OFF, Tractor Thinks PTO Is ON (and Sometimes It Is!)

[VaBeekeeper]

Hey Folks,

My Kubota L3901 HST is having a problem. I bought it new from the dealer this summer (only 20 hours on the odometer so far) and got the KTAC insurance, so I guess I should just contact the dealer and let him take care of the issue... but hey, if it's a minor adjustment I can do without voiding the warranty, I'd like to avoid the time and hassle of getting the repair shop involved. So I turn for advice to the great knowledge base of my virtual friends here in Internetville...

The problem is that my tractor "thinks" the PTO is engaged even when the PTO lever is in the Off position. And sometimes the tractor is right: after pressing the clutch pedal, moving the lever from On to Off, and slowly releasing the clutch pedal, the PTO resumes spinning. It's not supposed to do that! More often, the PTO shaft doesn't spin, but if I get up off of my seat, the seat kill switch kicks in and shuts off the tractor. Again, it's not supposed to do that.

I think I've sort of homed in to the location of the problem. (Please bear with me for this long-winded explanation, or skip to the next paragraph.) The PTO lever mechanism is supposed to press against a small switch when the lever is moved to the OFF position. But in my case moving the lever doesn't always cause the switch to be activated, or to stay activated. If I move the lever all the way to the very back of the slot it's in, until it bumps up against the edge of the sheet metal housing, then, yes, the switch activates. I hear a distinct "click" when that happens, and when I subsequently release the clutch pedal, the PTO does not spin. On the other hand, if I just move the lever far enough back so it can lock into the "Off" side slot position, without going all the way back to the edge of the housing, then the switch does not activate, I hear no tiny click, and the PTO shaft resumes spinning upon releasing the clutch pedal. Thus, it appears that the switch must be activated at least momentarily for the PTO not to spin. In either case, though, if I attempt to dismount the tractor, the kill switch under the seat shuts down the tractor. So that switch evidently must be pressed all the time to let the safety interlock system know that the PTO isn't running. Indeed, I am unable to start the tractor at all unless I take one hand and push the PTO lever all the way back while I use the other hand to turn the key.

So it appears that the PTO control lever isn't pushing on the PTO OFF sensing switch sufficiently, if at all, when the lever is in the rear, "PTO OFF" position. I took at look at the assembly and noticed that there is a lot of lateral play. To illustrate, I'll show you two photos for comparison.





Okay, so we have two photos of the PTO control assembly, looking from the back of the tractor just behind the seat. That big orange vertical bar is the PTO control lever; it's currently in the "OFF" position. Now take a look at the bolt and washer toward the lower center of the photos. Notice that in one photo, the bolt and washer are snug against each other, while in the other photo they aren't. That second photo, where there's some slack between the bolt and the washer, produces the condition where moving the lever to OFF uniformly results in activating the PTO OFF switch and keeping it activated (what we want). In other words, it seems that if the bolt were tightened so that there wasn't as much "slop" allowing the lever linkage mechanism to move laterally, the problem would go away. But I have taken a wrench to the nuts and bolt-heads, and I haven't detected anything that feels loose, and I don't want to force anything (remember my concern about voiding the warranty).

So what should I do? Does anyone out there recognize the problem and know an easy, low-risk adjustment? Or should I just play it safe and call the repair shop, even though it'll mean that my tractor is out of action for a couple of weeks?

By the way, thanks again if you waded through all my verbiage...

 

[s219]

The lever itself, and the slop, probably has nothing to do with it. When you move the lever, it operates a cable that moves a shift arm on the transmission case, which in turn actuates a dog clutch on the PTO countershaft to lock it in and engage the PTO output. It's a completely mechanical setup (except for the sensing safety switch, which merely cuts off the engine but doesn't control the shifting).

For some reason, when you move the lever back to off, the dog clutch is not disengaging. From what I can see in the parts diagrams, there is a torsion spring on the transmission case that is meant to make the PTO shift arm move back to neutral and disengage the dog clutch. I'd suggest you verify that the spring is doing what it needs to. There is also a pin on the external part of the shift arm that connects to the internal part of the shift arm. Verify that the pin is in place and connecting the various parts.

If you trace the cable from the lever to the transmission case, you'll see all that stuff. Have someone move the lever and see what is happening.

By moving the lever to off, the cable should go slack and the torsion spring on the shift arm should move it back to neutral. Verify that happens. I don't know if there's an adjustment in that cable (looks like you may be able to adjust it on the end near the lever), but perhaps it's not going slack enough. If there is still tension on it, that could cause what you describe.

Also make sure everything moves smoothly and is lubed. If any part of the mechanism sticks, it could cause the problems you describe.

I attached a screen grab of the parts diagram (I skipped the internal stuff, as I bet your problem is all external -- pray it's all external!!).

 

[teg]

....so I guess I should just contact the dealer and let him take care of the issue... but hey, if it's a minor adjustment I can do without voiding the warranty...

I would only ask the dealer about how to correct this problem. For one, he'll now know it a problem (maybe someone is not setting up the tractor correctly). The dealer will know if you can adjust it correctly over the phone - certain procedures to do.

I'll be surprised if they don't just send someone out there to adjust it correctly... especially, if you tell them you'll look for the answer on the internet!!!

 

[VaBeekeeper]

Thanks, folks. After looking at the assembly myself using the guidance of s219 and not finding anything obvious, I decided to take teg's advice and call the dealer. They sent out a guy to my house within 2 hours, who fixed the issue. The problem turned out to be the spray paint job that was done on the transmission case; there was a thick layer of paint that hindered proper movement of the mechanism.

 

[teg]

Good deal... glad the dealer did the correct thing (coming to the problem, to fix it).

 

[s219]

Thanks, folks. After looking at the assembly myself using the guidance of s219 and not finding anything obvious, I decided to take teg's advice and call the dealer. They sent out a guy to my house within 2 hours, who fixed the issue. The problem turned out to be the spray paint job that was done on the transmission case; there was a thick layer of paint that hindered proper movement of the mechanism.

Well that is great service, and certainly an oddball cause to the problem. Glad they got it figured out. Thick paint probably would have been the last thing on my mind! Which dealer did you buy from?

 

[VaBeekeeper]

Well that is great service, and certainly an oddball cause to the problem. Glad they got it figured out. Thick paint probably would have been the last thing on my mind! Which dealer did you buy from?

Hugh C. Gardiner, in Charles County, MD, across the Potomac River Bridge from me. Really great service, and Hugh is a stand-up guy.

 

[chili4x4]

Hey there.. I have a Kubota L3901 with the same problem.. I called my dealer who recommended spraying penetrating oil on the transmission case lever... I will definitely get up under there and check for overspray after reading your posts.. THANKS!!

 

[michaelwwaite]

Thanks, folks. After looking at the assembly myself using the guidance of s219 and not finding anything obvious, I decided to take teg's advice and call the dealer. They sent out a guy to my house within 2 hours, who fixed the issue. The problem turned out to be the spray paint job that was done on the transmission case; there was a thick layer of paint that hindered proper movement of the mechanism.

Any idea on why the PTO switch was not being depressed? I have a 2 year old Kubota L3901 in which all of a sudden it would not start. After some diagnosis, I found the metal arm of the PTO was not pressing the switch closed(similar to your complaint). If I manually pressed on the switch, the tractor would turnover and start. I then found if I pushed the PTO arm all the way back, it would press the switch and I could start the engine but the engine shut off *** soon as I stood up(PTO not engaged or spinning). I am looking for how this is to be adjusted properly. For now, I have padded the metal bar that presses on the switch with some duct tape. The tractor will now start with it sitting in thePTO disengauged position without having to press it all the way back. The swithh has a small straight silver arm with a slight bump on the end.that I guess is what gets pressed in to make the arm touch the contact.

Any info would be good
Thanks