M6800 pto problem

[massey4mike]

When I was running a 3 pt. hitch snow blower on my 2005 M6800, a very noticeble rattling/knocking sound started coming from the tractor. I at first thought something like a valve broke in the engine. I disengaged the pto and brought the engine back up to speed and no noise. I went back to snow blowing (just clean up, not much of a load) and the noise returned. I disconnected the snow blower from the pto, engaged the pto with no load and brought it back to 540 rpm with tractor not moving and no rattle. Also, the pto does not spin freely when disengaged, should it? Anyone have any clue what I should be looking for or what is going on?

 

[KennyV]

Sounds like something on your snow blower... check that first... KennyV

 

[BeezFun]

You can probably turn the PTO shaft by hand, might find a spot where the auger is binding or hitting something. If you can't turn the shaft, you should be able to turn the second stage impeller, you've got a pretty good mechanical advantage with that. You might have ingested something that's stuck, I've had every kind of dog toy, rope, fence wire and stick go through mine, things can get wrapped around the second stage and just stay there spinning around, hitting things.

 

[rbargeron]

PTO will not spin freely when disengaged - too much stuff turns with it. You can turn it by hand but it's stiff. Odds are there's something in the blower, or pto shaft that's causing the noise and it's telegraphing back through the tractor.

 

[massey4mike]

Thanks for the suggestions! Turns out there is nothing wrong with the snow blower as I checked it out thoroughly. I tried to use it again but this time as soon as I started to back up, a loud banging started coming from the tractor and it shook rather violently. The tractor runs fine without the pto engaged. Any ideas?
Sounds like I have a major issue but I have no clue as to what.

 

[Tx Jim]

Could the snowblower pto driveshaft u-joints be out of phase? Also a rough cross on a u-joint can make some noises. Also is driveshaft running in a staight line from tractor to blower or is off to one side?

 

[rbargeron]

........Any ideas?
Sounds like I have a major issue but I have no clue as to what.

Load banging is not good - my first guess is broken pto gear teeth. A couple teeth could be broken - it might still turn ok with no load but would make noise as the torque rises. You might be able to feel the rough spot by slowly turning the pto shaft back and forth with the tractor off. If that doesn't work, try holding a piece of wood against the pto shaft while it's turning at idle - might feel it or hear a click-click.

My first L345 made pto noise - it had 3 broken teeth on a pto gear (probably from hitting rocks with a rotary cutter). Had to split the tractor and change out the broken gear - the mating gear looked ok but I replaced it anyway to be on the safe side. The broken out gear chips were in the bottom of the case - cleaned them out and put it all back together with new oil and filter. Ran fine for years.

Not sure how the M6800 is built, but on other Kubotas the gear shafts have sliding couplings where they pass from one case to another, and all the bearings, etc. are sliding fits (not pressed) - makes it a little nicer job. Definitely get the workshop manual for your M6800. I go to Ronnie Bowman at Tractorsmart.com for parts. People like Messick's too. Good luck. Dick B

 

[638]

Perhaps a bad u-joint?

 

[sixdogs]

Could also have the implement lifted to too sharp of a driveshaft angle.

 

[massey4mike]

It is definitely not the blower or driveshaft. It is internal. Seems like the shaft that is supported by bearings through the casings lost on of those bearings and is flopping around when loaded. I unfortunately must wait for spring to investigate as I can't be without the tractor during winter. I can still take care of snow with a grader blade and the bucket for now. Where is the best place to get a shop manual?

 

[Tx Jim]

Where is the best place to get a shop manual?

I bought a TM for my M4900 at local Kubota dealer.It was $75, it's 3-4 "s thick and very infomative.

 

[sixdogs]

Not sure where to get it but you could also call a Kubota mechanic and ask a couple questions about the problem. Chappel tractor is near you in mid-south NH and is very helpful and friendly. I bought an M8950 from them years back and they couldn't have been nicer and shops aren't real busy right now. Years back I twisted my M8950 PTO shaft in a bizarre situation and had my local Maine guy come out and change it. It was before the shaft came out easily and they had to take a few things apart but it didn't take very long.

Your PTO shaft should just slide out by removing a few bolts. It is made this way to allow a swap to a 1000 RPM setup. I'm not positive on this but nearly so. Mine had a cluster of bearings and a geared arrangement. You can look inside then but first make sure you find out if your PTO lever needs to be tied back. Mine was hydraulic over mechanical and it did.
I actually still have my old PTO shaft and it was nearly twited halfway around but did not crack or break. In fact, it baled 2000 bales in that condition. Everyone thought it must be made of Krypton.

Anyway, before I got very far in calling a dealer I would make sure the driveshaft is not binding or some other simple thing is not going on. Narrow the focus.
You could search this site for Kubota manuals and that's where you can find info. "Smart Tractor" comes to mind. Keep us posted on this unusual situation. My guess is your PTO problem is something simple and my M8950 was built like a tank. Tough to figure it out at 20 below with a hard wind however. Good luck; this too shall pass.
Oh, my parts and shop manuals were serial number specific so know your SN#.

 

[massey4mike]

Thanks to all. I may give Chappel Tractor a call and see what they say although they could be a hundred miles from me. Something tells me the tractor needs to be split to repair but if it is something as simple as sliding out the shaft from the rear of the tractor and sliding in a new one, that would be great!

 

[sixdogs]

After what you say I am GUESSing you have a bad bearing.
I'll give you 85% odds it's not a big deal as long as it is not a bent implement shaft or something simple like that.
The big Kubotas are pretty hard to hurt so look real hard.
I have never seen a bad PTO or split larger Kubota. You can also call the regional sales rep.
These guys are smarter than it would seem.
I bought a tractor from Chappel and I lived north of Bangor, Maine.
It was 100 miles for me to get parts.

 

[HCJtractor]

Thanks to all. I may give Chappel Tractor a call and see what they say although they could be a hundred miles from me. Something tells me the tractor needs to be split to repair but if it is something as simple as sliding out the shaft from the rear of the tractor and sliding in a new one, that would be great!

I sent you an email. I have the shop manual and parts manual for this tractor so let me know if you need help. I will gladly share.

 

[massey4mike]

HC Tractor, I never got your email. I did buy a service manual which was helpful in knowing how the pto is designed from front to back but not so much, for me, in describing how to replace any given part. Do you know if the tractor must be split to replace a bearing or the shaft from the pto clutch to the rear?