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Snojetter

Kohler KT Starter

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Snojetter

I have an Allis 917 with a KT17 Series I.  This tractor is dedicated to my tiller and therefore is used only a couple times a year...poor thing.  Anyway, the starter motor bendix (I think?) sticks so that when I go to start it, the starter usually just spins without engaging the ring gear.  The starter is so well hidden, that it's basically impossible to do anything with the shroud on.  I can usually fiddle with it for a bit - key it off and on, use a screw driver and hammer to give it a tap, and it'll eventually engage so that I haven't had to tear it apart...yet.  But I'd just as soon "fix" this thing, so I have a couple questions:

1) My assumption is that the bendix isn't actually broken or damaged, but is just sticking from lack of use.  What's your experience with the starter motor - is this really a case of lack of use, or is there likely something broken or worn?

2) I haven't looked closely at how to access the starter, but it appears that I would need to remove the engine to get the starter unbolted and out of the chassis.  Is this true or is there a way to get it out with out major disassembly?

Thanks for the help!

Kyle Sands <>< Brandon, MN

Edited by Snojetter
mis-spelled words

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ShaunE

I have a guy I use for starter/generator rebuild local.  I pulled the motor to to remove mine.  It would be a good time to remove the shrouding & clean the fins thoroughly while your are waiting for the rebuild.  Even remove flywheel & clean the stator.  You won't believe how filthy it is.  I use a pressure washer.  Be careful to stay off crank seals directly & stuff rags in the intake.  Never had a problem with anything electrical doing this & have done this half a dozen times.  Also, I had the rebuild shop tell be to install the next larger gauge positive wire to the starter due to the length.  I did this but you probably don't have to.  If it has lasted 30 years before, I'd say you're good.

It was $75 for the rebuild 5 years ago.

Nice screen name!  Think I'll call you Thunder Jet!

Edited by ShaunE

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a_sannine

Take the shroud on the left side , few screws , spark plug , then u have access to starter , most of time dirt build up and some rust cause that , I just did a 917 was doing the same thing , clean it good as mentioned above , spray it with WD40 work it out few times forward /backward and u should be good to go .

Now if u need to take it out to do the brushes or rebuild it , take engine mounts out , don't disconnect the shaft , u can left the starter side up enough to undo the two nuts holding it .

 

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PGL

Al had the definitive answer for the starter problem back in 2008:

 

Al

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Hi, I would like to address the sticking drive problem This is a common problem with both Kohler and Briggs and all inertia drive starters. I will address the Kohler starters first. One word of caution! DO NOT STRIKE OR POUND ON ANY OF THESE STARTERS!!!! STRIKING THE STARTER WILL CRACK THE POWERED IRON MAGNETS AND THERE IS NO FIXING THE STARTER THEN!! The most common cause of the problem is the drive is stuck on the armature shaft. When the solenoid applies the 12 volts to the starter, the armature very quickly starts to rotate. The drive assembly has an internal helix on the inside (look like very coarse threads)on the inside and the armature has a helix (look like threads) on the shaft. The drive (part with the gear on) is "screwed back on the armature shaft against a shoulder on the shaft". The Drive has mass and when the motor starts to turn, the shaft spins in the inside of the drive. The mass of the drive makes it resistant to turn due to inertia. (Hence the name Inertia Drive starter) As it turns the drive is screwed out against a light spring to the ring gear of the flywheel. It is also starting to turn, but is free on the shaft at this time. When it gets to the flywheel and the gear teeth touch, it is able to mesh with the gear and continue to move to the "stop collar" on the end of armature shaft. At this point the gear is locked to the shaft and the engine starts to turn. Note: there is a rubber friction slip clutch inside the drive. This absorbs the shock load when the drive hits the stop collar and prevents this from breaking the armature shaft. This cushions the inertia load from starting the engine rotation. The gears stay meshed until the engine starts or at the minimum fires. When the engine starts the flywheel speeds up and turns the starter drive gear faster than the starter motor. Sometimes, the engine will fire and kick the starter out. When the drive is "kicked back" it is "screwed" back on the armature until it hits the shoulder on the shaft where is stays or is parked. If the engine has not started, the key needs to go to off and the cycle repeated. Because the drive will be spinning with the armature and there is no inertia difference to cause it to move out. The above actions happen very fast and are quite violent. When the drive is "kicked back" it "slams" back against the shoulder on the armature shaft. Over time the shoulder on the shaft will get "hammered out" and the outside edge will develop a sharp edge. When the drive is slammed against it, it caused the drive to tend to stick. When the starter is engaged, the armature starts to turn, but this sticking causes the drive to rotate with the armature and turn instead of "screwing out". If you could get to the drive and just push on a gear tooth to break it loose it would kick in normally. Another factor that can cause the problem. If the helix gets oil and dirt on it, the dirt will cause the drive to tend to spin with the armature before it reaches the flywheel. This results in the starter motor turning and not engaging the flywheel. There are other factors that can cause this problem. A weak battery, high resistance in the wiring, (ie, dirty or corroded cables") poor grounds including paint insulation. If the grond cable is connected to the frame and the engine is bolted to the painted frame and the bolts don't "bite" througn the paint this can crate a low starter torque problem also. Short or bad brushes in the starter can also be a factor. Anything that causes the starter motor to have low torque. As it is the quick torque of the motor that causes the drive to screw out. The most common fix: Kohler: Remove the starter and and remove the stop collar at the end of the armature shaft. Remove the drive, clean the helix on the inside of the drive. Take the starter to a wire wheel and clean the helix on the armature shaft. Also wire wheel the shoulder of the armature shaft where the shaft comes out of the bearing plate. Spray the shaft and helix with "Dry Graphite Lube" DO NOT GREASE! Allow to dry and reassemble. Reassemble. When you put the plastic spring cover back on make sure it has not shrunk and rubbing the on the washer under the nut on the end of the armature. If it is dragging on this washer it can cause the problem also. If this is happening it will really show up in cold weather when it will shrink and get harder. One thing that can help is to grind the outside of the washer down for more clearance. This normally takes care of the drive problem with the Kohler starters. Briggs starters have the same problem, and on them the gear is plastic and the helix is plastic. The plastic gear has less mass and is more prone to stick. Often you can take a small wire of screwdriver and reach up under the blower housing and just push a tiny bit on the gear and free it. Briggs has done several things to address the sticking problem. They revised the helix by putting a little blunt end on it and on the gear they blunted the end of the helix in the gear. This eliminated the little triangle on the gear and helix greatly reducing the wedging that was happening. Normally replacing the gear really helps on these starters, but about half of the time the “threads” or more correctly “splines” are worn and the whole drive needs to be replaced. We normally take the motor apart and check the brushes, bearings and magnets. I will do an article on assembling and reassembling the motors in another post as this is already tooo long. Al Eden
 
Many of the Kohler starters can be accessed and removed if you remove the engine mounting bolts and lift the engine up to 3 inches to get at the two holding bolts
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Snojetter

Thanks a bunch for the replies.  Grateful to know I don't have to pull the whole motor out to remove the starter.  I have no problem tearing into the starter if necessary but wasn't looking forward to removing the engine...I've done it before, just not my favorite job.

ShaunE - I used to be a Sno*Jet collector so this has been my go-to screen name.  Figured there's no sense in changing it now.  Still my favorite old snowmobile, but have moved on to other interests.

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MikeES

You can get to the starter without completely removing the engine.

Always disconnect battery before any maintenance work!

Remove the 4 mounting bolts engine to tractor frame.

Create a lift to lift the engine about 3 to 4 inches, I use a com-a-long from the shop rafter to the lifting lugs on the engine.

You will NOT need to remove the drive shaft, throttle, or choke cables. or electrical.

Remove the left side cylinder tin/shroud and you will then have access to the starter.

Remove the starter and clean the bendix, and lube with nothing thicker than WD-40.

Reinstall. 

I have done this many times.

 

Edited by MikeES

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Snojetter

Finally got the starter cleaned up and it seems to be operating smoothly out of the tractor.  Read my "Holy Crud" post to find out why it's not back in the tractor yet...hopefully it will be all reassembled soon.

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