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BigSix

Kohler K321 S Flywheel Cracked....

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BigSix
Hey All: I have a question on my oh-so-previously-messed-with Wheel Horse GT 14, concerning it’s Kohler 14 hp. (K321 S ), so I hope it’s okay to bring it up here. Some of you may remember that you’ve indulged my Wheel Horse questions before (perhaps because I have 2 or 3 Simplicities as well?). This is the tractor that was supposed to be in “turn key” condition (yet there IS no key—or ignition switch!) when I agreed to pick it up for my buddy, in return for being allowed to “mow” with it. I had 50+ hours in it before the first blade of grass succumbed…. Now (I think) I'm buying it, and it runs and mows well, once you jump the failed solenoid to start it, but read on…. I took the flywheel off, as my attempts to follow Al Eden’s excellent tutorial on trouble shooting the electrical system of Kohler engines lead me to discover very little AC voltage from the stator. (Thanks, Al! Your instructions are great—it’s the lack of most of the wiring harness, an ignition switch, and basic skills which are slowing me down now….:D) I pulled the flywheel, after removing the WOOD SCREW (!) that was holding one side of the magnetic ignition pickup to the aluminum bearing plate, and I discovered that the flywheel is cracked. :(! It has a crack running from the inner end of the keyway, and up over the inner edge of the shoulder of the hole the crank goes through. The crack is only 1/3” long, perhaps 1/64” wide (or less?) and does not run back down the outside of the crank hole shoulder. In other words, it just stops, 1/3” from where it begins. It does not appear to be fresh. I have a few questions regarding this, if you don’t mind: 1. I will put a wanted ad in the appropriate forum, here, but I wondered if anyone has a used flywheel to sell? The engine is a K321 S, Ser. No.: D259205, Spec. No. 6010B. The part number cast into the flywheel is 235806. 2. Must I find a flywheel from the same spec. no. of engine, or are they compatible with most (all?) K321 engines? What does the "S" in K321 S stand for, and must a replacement come from a K321 S or will any K321 suffice? 3. How likely is this flywheel to “grenade” if the crack worsens, and kill/injure me like a fan at a drag race before scatter shields were required on the meaner engines? Would YOU run it at WOT to mow with, while waiting to find a replacement, or not? I’m thinking that because the crack is neither wide nor long, that it’s not going anywhere. I’ve mowed with the tractor a few times so far, and the engine is very smooth. 4. The ends of the iron (steel?) plates of the layered stator cores, in the stator ring (and rotor ring inside the flywheel) are pretty corroded with that white oxide, and rust. I’m sanding them clean with some 150# sandpaper. What can I coat the magnets and ends of the core plates with that will prevent rerusting/recorroding, but that will not impede the magnetic mojo from generating? I don't want them to rust again, because if I sand them again, the air gap b/w the two rings will increase, albeit slightly, which I assume reduces their abiltity to generate electricity. 5. Does the electronic ignition system (it’s a breakerless engine with the magnetic pickup next to the flywheel) also get it’s juice from the stator and rotor under the flywheel, or from the battery? Because the spark is the weakest I’ve ever seen where the engine still runs—I was hoping the spark might improve when I clean up the under-flywheel magnets…. Thanks, everyone, for your indulgence in the off-brand questions. Peter

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D-17_Dave
Even if it looks old, the potential damage from the chunk of metal that large would be my cation enough to toss it in favor of a replacement. The other thing is if it comes apart and doesn't hurt you it'll surely cause your WH some terrible damage. Just for the piece of mind I'd be looking for a replacement. Now with that said, parting it out on ebeay would be my next choice.

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Marty-MN
Blowen flywheels can take the floor boards out of a truck. The damage is unreal. You would never know if it was safe, I would not take a chance on running it. Wish I could held with engine advise but no advise is better than mine on these

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maxtorman1234
DO not run it cracked, i would post a link to what can happen, but the page is gone. the fluwheel broke about 100 feet from the guys shop, went right through the siding and dented a support beam. I never run WOT when mowing, my engines last and cool proper, never had a problem. even though companies say to run at WOT, i find WOT is unnecessary unless you're trying to blow your engine, 1/2 to 3/4 throttle is plenty for me. thats just my opinion, flywheels from just about any k series engine will work, as long as they have the magnets,ring gear and trigger for your pickup. the pickup for the spark should work off the battery, and i would just clean up the ends of the windings with sand paper like you said, and put a clear coat of paint on it, its worked fine for me before, hope that helps you, o and I would also pull out the plug stuck in the hole for the points, get a point set, ignition coil, and plunger and then convert it to points, its way better. you should have good spark then, S stands for elecric start,

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BigSix
Marty and Maxtorman: I'm thinking I won't run it above a high idle, like if I have to move it around. Yes, it looks like the crack's been there for years, but I put big stress on the flywheel with (the proper) puller when I removed it, so I can't be sure it isn't more unstable than it was. So thanks for the words of caution on that score. Can I transfer my "rotor" ring, from the damaged flywheel, to another one (with the proper breakerless trigger bump? It's got four large Phillips head screws holding it into the flywheel. Thanks for the paint/points advice, and for decoding the "S". Re: WOT moving, this Kohler's governor keeps it at 3,400, which is still fast, I know, and while historically, I've been like you, not one to run them faster than necessary, this Kohler seemed to run a little warm, so I do/did run it right at 3,400. (I've pulled the shrouds and removed/degreased what little buildup there was on the fins, and the mixture's good. I had an intermittent lean condition before I rebuilt the fuel pump, and then after, due to fuel contam. It appears I've won that one...knock on wood.) Dave: I'm looking for a flywheel, like you said. If you or anyone have one in inventory, please PM me. I'm in NYS. Re: parting out my 1969 Wheel Horse GT 14 on ebay? Yikes! [:0]}:):D That's kind of harsh, no? Nice running (despite being much abused) Kohler 14, Cat. Zero 3pt. hitch, hydrualic lift, electro clutch and hydrostatic, 7 mph drive. It's rough, but it runs well, and it's very stable, gets mad traction, steers easy and mows a 48" swath, albeit not as scalp free as a Simplicity, axle-coupled, 42" deck, to be sure. Part it out? Shsssssh.... Surely you jest? LoL ;) Thanks again, Peter

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maxtorman1234
quote:
Originally posted by BigSix
Marty and Maxtorman: Can I transfer my "rotor" ring, from the damaged flywheel, to another one (with the proper breakerless trigger bump? It's got four large Phillips head screws holding it into the flywheel.
I guess you're talking about the ring gear on the flywheel for the starter, ive never seen one held on with screws, ususally they are pressed on , i think you can get them off but i dont think they will work on old flywheels without them. i have a bunch of flywheels here, ususally theres a bunch on ebay. heres one http://cgi.ebay.com/Cub-Cadet-1250-Tractor-Kohler-K301-12hp-Engine-Flywheel_W0QQitemZ7763388507QQcategoryZ82237QQssPageNameZWDVWQQrdZ1QQcmdZViewItem i dont imagine shipping would be much, ive had a block shipped here for little $$. hope this helps,

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IronPony
I repowered my 1978 AC712 by replacing the K301 with a K341. In doing so I found out that the K341 did not have a stater or stator type flywheel. I used the flywheel off my old K301 with stator and it has been doing just fine for going on 3 years. Did not make any other alterations to make it work; Just bolt off bolt on.:) The K341 came off a heavy equipment/truck "start all" unit and the engine ran off the vehicle battery that the unit was mounted in/on so it did not need a gen or stator of it's own and was not spec out from the Kohler factory with one. No one has mentioned yet that Kohler produced the K series with several different stators. You can find them listed in their Kohler manual with specs. Dan aka IronPony

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BigSix
Maxtorman: By "rotor ring" I may have used the wrong term. There is an alternator under the flywheel. The part that doesn't move, bolted to the engine case, is I believe called the "stator" (as in, it's stationary?) so I assumed the ring of iron plates and windings under the flywheel that moves with the flywheel is called the "rotor" but again, I could be wrong. Anyway, the winding magnet ring (the one that moves) is bolted to the flywheel, and I would have to change that over, I guess, unless he new flywheel had the same ring. Thanks for the auction link, as it gives me an idea of the cost, even though that flywheel is for a K301 and I have a K321. I'll keep my eyse open. Dan: I hope I will be as successful as your repair was, once I find a flywheel. I did know that there were several stators made, from Al Eden's very helpful tutorial on elect. trouble shooting a Kohler (available on his website--thanks Al!). From the type of plug on the regulator/rectifer, the Kohler Service Manual indicates that this should be a 15 amp alternator, yet that alternator allegedly is missing a couple of magnets, originally, from the factory, whereas the 30 amp model has every magnet hole filled, which is how my machine is. Someone opined that, based on the spec. number, my engine is a "service engine replacement" model for the tractor's original engine. If so, perhaps that could explain the 15 amp. wiring harness and 30 amp. flywheel? Dunno.... Thanks again, guys. I really appreciate your help. Peter

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Craiger
Working for a motor manufacturer, I can assure you the stator is a stack of steel plates (where motor strength is usually dependant on the stack width) and wrapped with copper windings. In electric motors, the rotor is usually another series of stacked plates (o.d. being slightly smaller than the i.d. of the stator giving you an air gap) with aluminum cast into them and a shaft pressed into the center of the steel stack. A magnetic field is created (called flux) when the electricity passes through the stator and energizes the rotor. Granted, I've not disassembled one of these, so take what I've described to be theoretical. I say that because there are instances where the rotor is stationary and the stator rotates around the rotor. I may have just described what you already know. And if so, I sincerely apologize.

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maxtorman1234
Ok, that flywheel from the k301 in the auction will fit, it is the exact same as a k241, k321 and k341.if it's off a k series and has a ring gear and magnets, it'll fit right on. Now, ther are 3 TERMINALS on a 15 amp rectifier, and 3 WIRES on a 25amp rectifier, all posts on the stator are wound on a 25 amp, but 2 arent ona 15 amp. it would seem to me you have a 25amp stator, also what winding moves with the flywheel? so if your rectifier has 3 wires, and all windings wound, its a 25 amp, the 30 amp stator has 4 wires, so its totally different. i hope that helps, also pictures would help alot :D

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maxtorman1234
I went out and checked, there are 15 amp stators with all posts wound around, i beleive yours is probably a 15, i'd just leave it the way it was if it was charging good. most flywheels have all the magnets, i wouldnt worry about it,

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BigSix
Craiger: I made a correction in red, above, that may correct any earlier confusion, but I think we're on the same page, in thinking that the stator is stationary and the rotor (generally) is the part that moves, in a generator/alternator. Sorry for the confusion. Maxtorman: Thank you for indicating which K-series flywheels will fit! Also, please see my correction (in red) to my earlier post, as I did not mean to imply that the winding half of the alternator turns--good catch!--I mean the magnet ring is what's bolted to the flywheel, and moves with it. Sorry 'bout that. :o) I didn't realize that there were 15 amp units where all the posts were wound--that's not what my Kohler service manual diagram shows, but of course, that's just one diagram. In any event, you're right, I have no need to change it if it's charging good. I don't yet know if it does charge, however, as I only got a volt or two, when I tried to check it's output, at the rectifier/regulator plug, prior to cleaning the winding posts and magnet ring. I did clean them up today, and painted them with Krylon clear acrylic. I've still got to patch the rust holes in the fan shroud before I replace it and fire it up. But since the charging is supposed to be measured at WOT, and I don't want to go above an idle with this flywheel, it may be awhile before I can test the output. Anyway, thanks for all your help! Peter

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BigSix
WOW--how much one learns when one bothers to read the literature at one's fingertips. For example, I learned that: Per the Kohler Engine Service Manual, sect. 8.4, "...the breakerless (ignition) system consists of four major components: 1. Ignition winding on alternator stator 2. Trigger module 3. Ignition coil assy. 4. Flywheel-mounted trigger The ignition winding is separate from the other windings on the alternator stator. It functions like the magneto winding." This was good news, as I now have hope that the barely-adequate spark will be improved by my cleaning/acrylicing of the stator winding plate ends and the magnet ring. I also learned, from my W.H. GT 14 Owner's Manual, that the GT 14 had a 10 amp system. Now, as my engine is allegedly a "replacement service engine," I don't know if the magnet ring and stator are OEM from the original engine, or came with a (possibly used?) replacement engine. But at least I know it's supposed to be the 10 amp alternator under there. Unfortunately, the Kohler Service Manual has no drawing of the 10 amp system, so I can't identify it by comparison to the manual. Regarding the flywheel magnets: I'm assuming I'll have to switch them when I find a used flywheel (which may not be the case, of course) but this WARNING in the Kohler Service Manual baffles me, from section 10.3 of said manual: "NOTE: Ignition magnet is not removable or serviceable! (they included the exclamation point!) Do not atttempt to remove ignition magnet from flywheel. Loosening or removing magnet screws could cause manget to come off during engine operation and be thrown from the engine causing severe injury. Replace the flywheel if magnet is damaged." This baffles me because the aluminum magnet ring is bolted into the cast iron flywheel with four, large panhead Phillips screws--these screws appear to be the only ones the previous abusers haven't boogered up, either. Were some of these engines' magnets held on by individual screws, as opposed to the the aluminum ring which is securely bolted to the flywheel on this engine, by what appear to be 4 1/4-20 screws? IOW, I can't see what the harm would be in unbolting this magnet ring and reinstalling it in another flywheel. Can anyone shed some light on this, please? Thanks again, Peter

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maxtorman1234
now i know what flywheel youre talking about its a newer one, you should never have to remove the magnets, because one without them wont have space to accommodate one, if you get another one, it probaly will have good magnets. I think the starter generators were about 10 amp, that would explain it, but i still would not worry about it. the flywheel will come as a complete unit. some magnets were glued or pressed in, held in by spacers between each magnet. i imagine the the stator and flywheel came with the engine. Just get a kohler flyweel, throw it on, if it has the trigger bump, magnets and ring gear it should be easy to find.

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