# engine vibration



## film495 (Nov 1, 2013)

ariens s12, k301S

so, if you were to count out 4/4 timing, just like counting to 4 at a normal pace. count 1, 2, 3, and on 4 my whole tractor seems to vibrate or shake, then 1,2,3 and on 4 vibrate. I think it originates in the engine and I'm thinking of checking motor mounts etc, figured I'd get lucky and maybe someone has seen this before. Only does it when throttled up near max throttle. I think I noticed this last year when snowblowing, but noticed it again this year while mowing, so figured I'd look into it. 

-Mike


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## Hoodoo Valley (Nov 14, 2006)

Can't give you any specific but there's no doubt that something is loose. Have you looked it over really well throughout and tried pushing on things with a stick or similar object to keep from getting injured?


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## film495 (Nov 1, 2013)

tractor beam said:


> Can't give you any specific but there's no doubt that something is loose. Have you looked it over really well throughout and tried pushing on things with a stick or similar object to keep from getting injured?


I started trying to go over it with a wrench to make sure engine mount bolts are tight etc. Did one side today before it got dark and did put a little extra "tight" on the bolts, but would not have said the ones I checked were loose. 

I did notice on the other side, the right front bolt is new, so it was replaced before I owned the machine, so maybe I'm onto something. I didn't get a wrench on it today, so I'll see tomorrow hopefully.

I think it only does this vibration pattern when the PTO clutch is engaged and a load is on the engine.


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## Fredneck (May 25, 2012)

ya, good chance the new bolt is an indicator that the original just fell out.

i was surprised to find out how often mower engines work their way loose of the mounting bolts. i just had a friend determine that a suspected rod knock was exactly this, and i had this issue with mine a few years ago. lockwashers and loctite are good products 

i hope this turns out to be the case for u, mechanical problems don't get much easier to fix than that.


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## film495 (Nov 1, 2013)

well, I was wrong, that bolt is original, I just remembered seeing another one that holds the grill onto the front was new, and remembered it wrong. anyway, I've put a wrench on the bolts for the motor mounts, and anything down in that area that I could get a wrench on to tighten it up. I've been unable to recreate the vibration, but it wasn't doing it all the time, just at the right speed with the PTO engaged.

One thing I noticed today while poking over the machine, is that the flywheel screen seems to have a little wobble in it. So, I tried to look at the flywheel and it certainly looked normal, but what I did see was that the drive shaft seems to have about a 1/4" wobble at each end at low rpm. It seems to be straight as soon as I add any rpm to the engine, but I did notice there seems to be some wobble in the shaft at the engine end and the transmission end. Not sure if that is a problem, or how I would even begin to go over it?

One other thing I noticed was the aft part of the drive shaft has an assembly, where I can see has bolts that appear to have made contact with the bottom of the floor plate there, and made some decent marks/indentation in that spot. What I thought was just harmonic vibration when snowblowing, going slightly up hill, full RPM, PTO engaged, with snow going through blower, that floor plate vibrates, and may have actually been the 4 bolts connecting the drive shaft assembly, slightly impacting the floot plate, since there are impact marks there, not sure why it would do this at that particular spot in the driveway, and not all the time?

Maybe the extra load/torque, causes it to have more stress and thus a little more motion?


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## jhngardner367 (Apr 5, 2011)

Check the crank shaft bearings.


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## film495 (Nov 1, 2013)

jhngardner367 said:


> Check the crank shaft bearings.


You make that sound so simple. I have a couple service manuals for the K301 motor and looking through not sure how to check the bearings. If I have to do anything significant to this machine I'd like to do it now, before winter when I need the machine to work.


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## film495 (Nov 1, 2013)

Well, I got an hour to look over this again before it got dark, and when rotating the drive shaft by hand, there appears to be what I think is about a 1/8" curve in the shaft itself. It has no play or movement when trying to see if the each end is fully secure, and no back n forth movement either. 

I closed it all up and put the floor plate back on and started it to see what would happen ......................and

seemed fine, so I ran it up and down the throttle slowly and I get the basic noise vibrations I expect out of the hood have a little rattle/rap at a certain rpm from handles and what not, and at about 3/4 throttle I hear that noise, softer but it sounds like the same sort of higher pitched noise, that is much more metalic and just bad sounding like something might explode. I go up and down the throttle a couple more times, and there it is right at that exact spot in the throttle, and I notice it is coming out of the floor plate, and I figure the bolts that hold the drive shaft must be making just tiny contact with it at that rpm and making the "your tractor is going to explode and kill someone noise."

since I've seen that same floor plate rattle, I put my fingers down on it and well - no more noise. So, I guess if I'm lucky - the whole issue is that floor plate rattles at a specific harmonic vibration, and just makes the worst noise ever. Maybe not, but I'll add some more bolts to hold the floor plate down better and see if I ever hear/feel that same vibration again.


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## jhngardner367 (Apr 5, 2011)

Lay a straight-edge on the shaft,to check for that "curve". It can sometimes look curved,but not be.
Are there any marks on the bolts for the drive shaft,like they were nicking it ?
Good idea , on the extra floor plate bolts!
These "mystery noises" can drive you nuts,at times !
My Bolens has the same engine,and had sat for 7 yrs,and when I fired it up,it had a weird clicking "rattle". After checking everything on it, I pulled the cooling shroud. 
Varmints had left some acorns in it,and they were bouncing off the inside of the shroud,and the flywheel !


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## film495 (Nov 1, 2013)

that's a great idea, I'm going to check it with a straight edge. 

i need to get time to check it out again, I didn't see marks on the bolts, but I didn't have time to look really good. it could be old marks dating before a previous repair; some of the attaching hardware on that end looks newer than some of the other pieces down there. 

I'm also not sure that just because when I put my hand down on the floor plate and the rattle went away, doesn't mean those attaching bolts aren't making a slight impact at the particular 3/4 throttle speed anyways. maybe I'll put a piece of masking tape on that spot and see if it gets ripped right in the middle. 

If it does rip, I could add in some small washers under the floor plate to ad 1/16" additional clearance, but not sure that would be really fixing the problem if there is one.

Yeah, noises are a bugger, weird noises, especially when thinking about the reality of those noises coming from high speed metal object rotating between my legs ... be afraid, be very afraid.


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## jhngardner367 (Apr 5, 2011)

You could always sing soprano,in a choir!:lmao::lmao:
I had a drive shaft on a JD317 throw a cross-joint,at full throttle once...........ever hear the saying"scared the poo outta me !" ??? it does!


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## film495 (Nov 1, 2013)

found googling, so at least I know someone has seen the same thing happen...

"I can post fan pics if someone needs them. I just took 2 of the three nylon spacers out of mine cuz it was making the drive shaft end hit my floor pan. Not really sure whey the original owner did that. I wonder if I even need the nylon washers in there or if I can bolt it up without. I'm assuming its just a vibration dampening thing. "


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## film495 (Nov 1, 2013)

so, I mowed again and I heard the same type of sound, and I just don't like it. so, I pulled the hood and front grill, and floor pan, and started looking for things that can move/rattle. I'll make my project notes here so I don't forget.

thinks I think may rattle - and sound bad

exhaust pipe coming out of grill on side
floor pan
shaft/rod to front lift has a lot of movement, add washers
neutralizer pedal tighten
feet/risers, forget what they're called, where you put your feet, are loose
drive shaft coupler, sometimes hits floor pan, scootch floor pan forward and tighen
hood / I can add some foam to take car of this, did it before

I put the muffler back on and ran it without the hood and front grill, and a lot of the noise was not there. I'm going to tighten up these other parts just 'cause.

The tractor, at low RPM just sort of waddles a little side to side as far as motion, vibration goes, seems normal to me, but what do I know. At higher RPM it vibrates pretty good, all over, but not enough to say make your fingers numb from holding the steering wheel. 

Hopefully, I can get another season out of this thing blowing snow - so I'm going over it again.


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## jhngardner367 (Apr 5, 2011)

To check the crankshaft bearings,all you do is push it back,and forth,then side to side. 
Any movement larger than 0.015" shows wear.
Have you checked the timing,by any chance ? It should be at 20 degreesBTDC. .
On the side of the cooling fan shroud,there's a round hole. If you shine a light in there,you can see the timing marks.


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## film495 (Nov 1, 2013)

well, I didn't manage to get a straight edge on the drive shaft, but by eye as I rotated it by hand, it had some sway to it, either from being off center at one end or the other, or it is bent. 

I took some pics of further discovery, will post at some point. one of the bolts on the coupler at the back end of the drive shaft is actually worn away about 1/8" as well as are the threads on the bolt, from impact with the floor plate. the floor plate has some good wear marks as well. I think this is partly due to the floor plate being attached poorly, and sliding backward and creating the contact. not sure how much of the marking is new and how much is old. I put a couple new bolts through the floor pan and have it held in pretty snug now. one interesting thing is only one of the bolts that hold the coupler has damage, but there are 4 that really should all rotate in the same plane. 

while I was in there, I added a spring to the neutralizer pedal so it would return to upright after pressed. I found the half remaining broken spring hanging there and happen to have one that fit. also, added a bolt to the footrest where the old one had started to rot out, and I broke it putting a wrench on it; so got a new one in.

I played with the points, and found an S mark and an I mark, on the flywheel. I thought it was supposed to be an S and T mark, but maybe I'm seeing the T as an I, but it is a little hard to read, there is a line under each mark. I managed to break the points that were on the tractor, and happen to have a replacement set that was new, so I put that in and set the gap to .015 just to see if it would make any difference. I could not find any real correlation between the marks on the flywheel being lined up to the site hole and any behavior of the points, didn't seem to open or close or do anything as I rotated it, but that was before I found the broken points, so maybe that has something to do with it.

So, at .015 I see no difference in how the motor starts or runs as opposed to the .02 setting. I'll likely muck with it a little more when I have time. The whole machine still has some nominal vibration, I think is normal, but how would I know.


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## film495 (Nov 1, 2013)

I was reading about this and for the life of me could not find any real way to figure out how to get the S and T marks to mean much of anything without a timing light, but then I thought - oh, I made marks with paint on the flywheel screen and housing so I could line up and find the marks again later. Well, that's only easier than looking through the sight hole, but then 

- if you open the points gap, this is advancing the timing, if you close the gap - you are retarding it, so - if the flywheel spins clockwise looking from the flywheel end, then I can, - see if the S mark is before or after when the points start to open, and either widen the gap or close it based on the timing fo the points opening in relation to the S mark being early or late. 

I haven't done it, but I also think attaching a test light to the points, is on vs off, when points are open vs closed. so may be able to figure the exact spot to determine if the flywheel markings of S is early or late. Yay! 

Maybe anyone who does this should really invest in a timing light, but I feel good that I may have figured this out in my small brain.


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## jhngardner367 (Apr 5, 2011)

Try this site.
It's where I got my Kohler engine manual from.
You can download them to disc,or your PCs "Documents" file. It opens with adobe reader.

http://www.kohler-engine-parts.opee...-manuals/free-kohler-service-manual-downloads


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## film495 (Nov 1, 2013)

after mucking around, I was able to get the timing set about 1 degree late, and that's about as close as I could get it, so I stopped adjusting it. put the grill and hood back on, tightened it all up. I ran some seafoam through it, then adjusted the carb settings again. Seems to run strong, but I would not say much/any different than before, but I got a good education and discovered how many things on a tractor can rattle/vibrate.

I'd swear there is a slight rattle/knock sound that I can't identify that sounds like it comes from the motor. It does not make the sound at idle, but probably around 2,000 rpm is there. I can't hear it unless I make a point to listen for it - with the tractor out of the garage, in the garage the motor sound is too loud and I can not hear the rattle, outside if I move forward, the sound of the hydrostatic makes it so I can't hear it. I was trying to see if some load on the motor made a difference, but it is so slight I can not hear it with any other sounds going on, but I'm pretty sure it is from the motor.


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## film495 (Nov 1, 2013)

hmmm... wonder if my 87 octane gas could make it do that?


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## jhngardner367 (Apr 5, 2011)

The 87 gas shouldn't make it do it,unless the timing is retarded too much. Timing on these is at 20 degrees. 
With the engine OFF,rotate the engine until the "S" or "SP" mark lines up. Continue to turn the engine,slowly,until the points are fully open. Set the points at 0.020 ".


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## film495 (Nov 1, 2013)

http://www.aircooledvwlove.com/how-to-set-ignition-timing-on-an-air-cooled-vw/

I basically used the manual method outlined here, using a test light. 

I got the timing to be about 1 degree late, of the S mark, so I left it there.


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## film495 (Nov 1, 2013)

did a little searching and guess the kohler knock can be to much play in cam shaft, or connecting rod, or a bearing in there. I guess if it isn't too loud I'll just run it.


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## jhngardner367 (Apr 5, 2011)

Just run SAE30 oil in it,and it should help.


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## film495 (Nov 1, 2013)

just cause I can't help myself I experimented with this a little more today. the knock or ping I hear, sounds more like a small rattle, like there is a ball bearing floating around the engine, but it is related to engine speed and changes in relation to the throttle setting.

another note of interest, it only makes this noise as far as I can tell starting at 1800 or 2000 RPM, which is just about when everything else on the tractor will rattle a little as well, so it must be the harmonic of the engine at that RPM range. when I go over about 2500 RPM, I can not hear it and it does not rattle at Idle or as far as I can tell, or when the engine is cold.

another interesting thing is for the most part, I can make it go away by applying load to the engine. If I start to creep forward or backward I can make the rattle go away. I can also create the rattle when I'm slowing down or sitting still.

so, I don't know much about engines, but what in there will rattle, that when there is a load applied, will stop rattling. possibly due to torque being applied?


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## jhngardner367 (Apr 5, 2011)

Loose crank/cam bearings.


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## film495 (Nov 1, 2013)

Is the cam bearings something I can check through the cam cover? why is there a cam cover anyway?

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I read crank bearings will likely make noise at startup or under load (opposite symptoms I'm seeing), and I don't think it is rod knock(not hard or thumpy enough), and that leaves the cam.

My guess on this (from internet searching) is that from years of wear, the play in the cam shaft has grown, so the end of the shaft actually taps or rattles on the thrust plate. When under load, the shaft is held, or pressed(thrust) against the plate, and no more rattle, knock, metal to metal sound. 

I'm not a mechanic and I honestly don't even know if the K301 motor has a thrust plate at the end of the camshaft to tap against, but as far as I can tell from the information available to me, it is at least a decent working theory.


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## film495 (Nov 1, 2013)

well, for kicks I held a board over the exhaust pipe just to see what would happen. so, restricting the exhaust a little, or a lot, seems to make the rattle go away all together. maybe I'll order a new muffler and see what happens. 

anyone know a good way to seal the fitting at the motor end of the muffler. I'm pretty sure the attachment between the muffler and the exhaust pipe is not sealed completely by the clamp that is there.


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## film495 (Nov 1, 2013)

pulled muffler, checked out, no holes, no rattle, a little rust fell out - just dust - reseated muffler better and added some gasket compound to the joint at the engine so the clamp would make a better seal. tried putting board to exhaust like I did before, and it starts to stall out engine, so fixed the exhaust leak, engine still makes a little knocking rattle noise.


well, it just sort of dawned on me that maybe it is the front PTO? I'd go outside and test it right now, but it is 11PM and my neighbors would have solid confirmation of my crazy, so maybe tomorrow.


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