Vibration @ high rpm

[persof 14]

My 312-8 runs great. At 1/2 throttle where I plow snow, pull a cart and run my tiller (2/3 throttle) the vibration is moderate, but mowing the grass at full throttle for a while and my hands tingle for 15 minutes after I shut down.

Is this the way it is or can it be reduced?

Thanks

Francis

[Duff 206]

Wow, Francis - not a good symptom. I've got two M12's on 312-8's and neither vibrates at any RPM. I'm hoping one of our experts like TT jumps in on this. The only thing that comes to mind, and it's a way long shot, is on one of my Dad's green tractors that developed a vibration we found that the main drive pulley had started to split creating an out-of-round condition. This was a sheet metal pulley that was made from spot welding the two halves together. It's unlikely a cast pulley on a has split, but maybe the clutch/idler pulley?

Duff :)

[rmaynard 14,932]

I would check to make sure that something has not built a nest behind your flywheel, or stashed something in the vanes. If the problem has just started, it's that time of year when critters are looking for a winter home. I had chipmunks stash acorns behind the flywheel cover on one of my tractors. They lodged between the vanes and threw it off balance. Thought it was going to shake apart until I found the source.

Bob

[Sparky-(Admin) 19,652]

Have you checked to make sure the motor is bolted tight to the tractors frame. Just a thought .

Mike.........

[persof 14]

I had the skins off the other day in order to replace the starter. My deck is very noisy, is it possible that the deck has a vibration that is xfered to the steering wheel??? I will man the throttle with the deck disconnected and report the results.

Thanks

Francis

[Duff 206]

My deck is very noisy, is it possible that the deck has a vibration that is xfered to the steering wheel???

Yes, that is very possible, but didn't you say there was also some vibration using the tiller or just towing a cart? Hmmmm.....

Duff :thumbs:

[HankB 16]

Have you checked to make sure the motor is bolted tight to the tractors frame. Just a thought .

Mike.........

Excellent point!

I found the two left bolts loose on the M14 on my 314-H. I bought it new and never removed the engine so I guess these just have a tendency to vibrate loose. I used Loctite on them before I tightened them.

Since the OP noticed the problem when mowing, I'd also check for problems with the deck and mule.

-hank

[stevasaurus 22,259]

If it is in the deck, it is possible that the blades are out of balance. Take off the blades and hang them on a nail in the wall to see if the are balanced. Sounds primitive but that is what the manuals say to do when you are sharpening the blades. Also check to see that they are on correctly. :thumbs:

[whfan74 2,015]

Steve is right on..........many of us have put the blades on upside down accidently. That will definitely give you a shake that you aren't used to.

But like was mentioned before it seems to happen with any attachment. I would check the bolts as well first, then start searching for obstructions. Like we have all heard before........K.I.S.S. Keep it simple stupid...........not that I am calling you stupid, sometimes we get lucky and it is the simple fix. :thumbs:

[persof 14]

Checked engine to frame bolts and they are tight. I checked the under deck baffle and they appear tight. I removed the blades and did a meticulous balancing on them using care to ensure that they were installed correctly. I also put a ruler against the underside of the deck and rotated the blades to verify no bent blades or shafts, looked "OK". I also attempted to perceve if there was a varying of deck belt tension but if there was any I coulden't detect any. Is it possable that one of the pulleys is out of round?

I think that single cylinder engines are prone to vibrate at high RPM, But my deck has a powerful vibration and a LOUD buzzing sound like "braaaa ___Braaaa___braaaa ( my neighbor can heari it from his yard ).

Ideas???

Thanks

Francis

[Duff 206]

Francis, your symptoms are identical to the problem I had on a green tractor when a pulley split creating an out of round condition. The noise and vibration became hideous very quickly. Another possibility is a spindle bearing has died. Can you take off the belt and turn the spindles to see if one of them feels rough or is grinding?

Duff :thumbs:

[oldandred 15]

why not slide off the pto pully and then run the engine if it still there its the engine

could be a balance gear broken ???? :thumbs:

[Duff 206]

why not slide off the pto pully and then run the engine if it still there its the engine

could be a balance gear broken ????

oldandred, you may have hit on something here.....could be the bearing inside the PTO has let go, too. That would probably vibrate with high RPM's and load....

Duff :thumbs:

[persof 14]

All spindle bearings were replaced when I first got the deck as it was much noiser than now. I also replaced one of the spindle shafts. I also replaced the idler tensioner shaft, bushings and spring.

I must confess there are two issues here that may be linked:

High engine RPM for 40 minutes makes my hands tingle.

and

Deck makes a loud pulsing noise and has a strong vibration when running at speed.

Is there a balance gear in the engine?

Thanks

Francis

[Duff 206]

Yes, there is a balance gear in the engine. But if it is the balance gear and the problem has been going on this long, I'm surprised it hasn't "grenaded" already.

Even though you replaced the bearings and one spindle on the deck, my money's on either one of the new bearings having gone south (it can happen, as I found out ), the other spindle having developed an issue, or there's something wrong with one of the pulleys. All that vibration and racket from the deck just ain't normal!

Wish I had another thought on the engine, but I'm plumb out of ideas.

Good luck!

~Duff :)

[MaineDad 85]

Does it vibrate at WOT when the deck is NOT engaged?

[persof 14]

yes it does. I looked in the Kohler service manual and they show the ballance shafts that Duff mentioned and it says to take care in installation to ensure proper orentation of the ballance shaft - vs - the crank shaft.

Francis

[stevasaurus 22,259]

I am at a loss also, but will watch in case something pops up. :thumbs:

[Guest]

... Is it possable that one of the pulleys is out of round? ....

I think that single cylinder engines are prone to vibrate at high RPM, But my deck has a powerful vibration and a LOUD buzzing sound like "braaaa ___Braaaa___braaaa ( my neighbor can heari it from his yard ).

Ideas???

Thanks

Francis

I would want to eliminate the pulleys as the root. There may just be some debris lodged in one of them and you might not feel it turning the blade through by hand. Looks like you've crossed blade imbalance off the list - and you said they weren't bent (rotating out of plane) so why not take the belt off and give the pulleys a quick look? Then you can really look at the spindles again, too.