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?