rbstuartjr Posted March 2, 2019 Posted March 2, 2019 So my 910’s engine died while snow blowing 2 weeks ago, since then I have gotten my new to me 1996 sovereign.so I finally got around to the 910 to check some things out on it. I pulled the engine, which is a K321 to,see what went wrong. I pulled the shrouds and and the flywheel and saw that one of the magnets let go and destroyed the stator and shorted it out. There were chunks of magnets all over the stator and the flywheel. I also feel there the rod is loose on the flywheel giving me the rod knocking that I was hearing under load. This engine started almost instantly and did not burn any oil. So it looks like I need a new flywheel and stator. I am tempted to,look for a new crankshaft as this one has been turned before and running an undersized rod as it is. I will be scouring eBay as there are no local places for used engine parts. I figure since she is going to be down for a while I was going to check on the BGB. The cone clutch has about a 1/2 play before the driveshaft will turn. I pulled the cone clutch and see the woodruff key is half it’s thickness on one side. So that might account for its play. I grabbed the driveshaft and the held the drive pulleys at the BGB and there is about 1/16- 1/8 inch of play. Is that acceptable? There is no grinding sounds or any bearing noises from the BGB. The seals aren’t leaking. I checked the fluid, it is dark and is half way up the dipstick, I must have overfilled it when I changed it last. Would you pull it to rebuild or leave it as it is? one other thing is the cone clutch pulley bearing. It’s not squealing or anything but there is definitely some wear, do these last a long time? At a price of $80-90 I don’t want to replace it if I don’t have to. I have the service manual but am looking for some advice. Thanks all.
Chris727 Posted March 2, 2019 Posted March 2, 2019 If the bushing inside the bearing is bad, it might be time to replace it. If its going bad you will typically hear a noise when clutching it with the PTO off. With the tractor not running and the PTO disengaged you should not be able to wiggle the cone clutch pulleys very much. If its fairly loose the bushing may be wore but I would suspect other symptoms would have also shown themselves if that was the case. As for the BGB, 1/16 to 1/8 of rotational play is very good and about the best you can hope for. 1
ShaunE Posted March 2, 2019 Posted March 2, 2019 13 hours ago, rbstuartjr said: one other thing is the cone clutch pulley bearing. It’s not squealing or anything but there is definitely some wear, do these last a long time? At a price of $80-90 I don’t want to replace it if I don’t have to. I'm not sure how necessary the bushing in this bearing is or what it's purpose is other than to shim from 1" to 7/8". I have replaced a few of mine with Timken 1014KRR. This is the correct size bearing with a 7/8" I.D. so no bushing needed.
PhanDad Posted March 2, 2019 Posted March 2, 2019 1 hour ago, ShaunE said: I have replaced a few of mine with Timken 1014KRR. I also did the same. So far, so good. I believe the OEM bearing has a slightly larger ID and that's the reason for the sleeve; makes it easier to get on and off the shaft. I remember having to use emery cloth to clean up the shaft. I might have reduced the shaft diameter a bit. The old OEM bearing slid on the shaft before the "clean up". Some pics of the old bearing and the 1014 KRR bearing I installed:
rbstuartjr Posted March 2, 2019 Author Posted March 2, 2019 Thanks for the part info on the bearing. Still not exactly a cheap bearing but definitely better then the $80-90 simplicity one. I am going to pull the pulleys off and check the sleeve/ bearing and shaft for wear. At first when I was checking the bgb for play, the cone clutch rally moved a lot before the input shaft did. That woodruff key really took a beating and not the shaft or clutch. She sees more snow blowing than mowing, so I wonder if that what accounts for wear in the key.
Chris727 Posted March 2, 2019 Posted March 2, 2019 4 hours ago, ShaunE said: I'm not sure how necessary the bushing in this bearing is or what it's purpose is other than to shim from 1" to 7/8". I have replaced a few of mine with Timken 1014KRR. This is the correct size bearing with a 7/8" I.D. so no bushing needed. Interesting. I assume this is a much less expensive bearing? I had a 7010 once that when you pushed in the clutch pedal with the PTO disenaged it made a vibration and noise from the cone clutch. I found that the ID of the bearing/bushing had become worn and had resulted in wear on the BGB shaft. I had a good used bearing I installed. This corrected 98% of the problem but over time it would need a new cross shaft in the BGB as well as a brand new bearing.
Chris727 Posted March 2, 2019 Posted March 2, 2019 Every now and then the OEM bearing shows up on eBay for less than $50. Part number is 1650254 or currently 1650254SM
rbstuartjr Posted March 2, 2019 Author Posted March 2, 2019 Since we all love pictures here’s the woodruff key from the cone clutch, stator and the flywheel form my K321. When rose magnets came off it stopped that engine dead flat. It also shorted the stator to ground . Which is what I believe stopped the engine from firing. But after it stalled I couldn’t even turn the engine by hand.
Alltractoredup Posted March 2, 2019 Posted March 2, 2019 Yikes, that's unfortunate. Nice and clean under there. Ebay has these flywheels all the time.
PhanDad Posted March 2, 2019 Posted March 2, 2019 3 hours ago, rbstuartjr said: Since we all love pictures here’s the woodruff key from the cone clutch Maybe they sell that type of woodruff key; the one I found that drives the bevel gear on the cross shaft looks a lot like yours: 2
ShaunE Posted March 2, 2019 Posted March 2, 2019 So much for posting about re-gluing flywheel magnets as yours don't look to be salvageable. This is my biggest fear with my Onan CCK-B.
rbstuartjr Posted March 3, 2019 Author Posted March 3, 2019 PhanDad, After seeing that woodruff key on the cone clutch, I was thinking that maybe they all were getting worn in the bgb. But after seeing how tight the the other pulleys are with the input shaft plus not leaking, I’ll leave it alone. Shaun, I had glued one of those magnets back on during one rebuild. I think one came loose grabbed onto the stator and tore the rest of the magnets to pieces. After I took the flywheel off, I was pulling chunks of magnets out of the stator. So I placed an order order for a new “used” flywheel and stator off eBay today. I wonder if they sell magnets, I could always chisel out the bad ones and reglue new ones.
ShaunE Posted March 3, 2019 Posted March 3, 2019 I had good luck with re-gluing flywheel magnets. preparation being the key. Evinrude sells an epoxy kit for $6 & change specifically designed for this purpose. It is a very common practice in the marine industry but for some reason is considered "Taboo & Risky" in the lawn & garden world. Most likely because of debris & heat buildup. My Command flywheel. Three out of the six magnets. Holding strong after two years.
rbstuartjr Posted March 3, 2019 Author Posted March 3, 2019 When I did it, used a two part epoxy JB weld type. The one that let go was not the one I glued. That one is still holding strong. I wonder, if when you see one come loose, that the others aren’t far behind. 1
ShaunE Posted March 3, 2019 Posted March 3, 2019 I had one that had came off & was spinning on the outside of the stator. I noticed the Ammeter was not charging like normal so I removed the engine & flywheel. When I was cleaning it, I pressed as hard as I could on the remaining magnets & two more popped off.
rbstuartjr Posted March 7, 2019 Author Posted March 7, 2019 So I tore down the rest of the engine today. I did order stator, flywheel and crankshaft that was mic’d at 1.50, standard size. I was nervous about a used crank, but after getting it measuring it myself, she is indeed in standard size spec. Before tearing it down, I grabbed the crank snout to check for looseness in the rod because it was knocking pretty good, even though only having about 60 hours on a rebuild. She always vibrated pretty good, but I was told that was normal for these engines. So I pulled the oil pan and look what I see, is that a small crack in the crank? Now mind you this crank still till turned and the piston moved up and down, but had a small amount of looseness noise I assumed was a loose rod. So this is the crank, piston and the oil pan. After last rebuild, I did epoxy 2 very strong magnets in the oil pan to,collect metal shavings. And they both were coated and there were some metal,flakes in the bottom of the pan. So I think I’m just going to deglaze the cylinder with a hone and throw a rebuild kit with new rod and piston in it. The cam end play is at .010 which is the high end, so I will reshim it to get closer to .005. She had new valves, valve guides and valve job at last rebuild. . I’ll take some advice on how to keep the vibration down on these things. This one did come with balance gears that I already removed. There was no difference in vibration with the gears btw. 1
RAC Posted March 8, 2019 Posted March 8, 2019 Almost looks like a crank that was reground improperly and the radius not done right resulting in a stress crack. Never really seen one do that.
rbstuartjr Posted March 8, 2019 Author Posted March 8, 2019 So upon getting the new crank, she weighs about 3/4 ounce less then the old cracked one. So I’m probably going to bring the the new crank, rod and piston to my local machine shop to see if they can balance the assembly. I knew the old one was out of balance, but upon reading up on this, that an out of balance crank can lead to cracked crank or rod. I have had both those things happen to this engine. The first time I rebuilt it was the rod blew apart, now the crank cracked. 1
PhanDad Posted March 8, 2019 Posted March 8, 2019 Sounds like more $$$ down the single hole toilet to me. Now if it were a twin hole toilet.... 1
RAC Posted March 9, 2019 Posted March 9, 2019 (edited) You can't really balance a single. I mean, there's a rule of thumb for the counter weight mass, but it will never be truly dynamically balanced. That's why they use the counter weighted gear systems. As far as out of balance causing the crank to fail... Doubt it. It'd have to be so far out the tractor would bounce up and down at idle. I'm running left over pulling parts in the 14 Kohler in my tiller/snow blower tractor. Forged piston, extra long billet rod, all added up, way heavier than stock. Definitely further out of static balance than that motor is going to be. I'd say you probably cracked the crank when you dropped the rod and the crack propagated after you put it back together. Edited March 9, 2019 by RAC
RAC Posted March 9, 2019 Posted March 9, 2019 Did you check the cam real good. Usually when the rod fails in a K motor it whacks the cam and cracks it too.
rbstuartjr Posted March 9, 2019 Author Posted March 9, 2019 I’m going to pull the cam when I add a shin toit, so I’ll check. The rod hit the bottom of the cylinder skirt and put a small crack in that. So I think that spared the cam, but I’ll double check it. So would 3/4 of an ounce difference in crank weight make it vibrate that much worse?
RAC Posted March 9, 2019 Posted March 9, 2019 Hard to say. It depends on where the 3/4 ounce is. Near the crank centerline-no difference, at the outside edge of the counterweights - maybe a noticeable difference, in the throw - maybe a little difference, evenly distributed - probably no difference. If you have a crank from the same size engine then it was statically balanced before it left the Kohler plant regardless of the overall weight. Not worth messing with. Running a 12 hp crank in a 16 or vis-versa then it'll probably vibe a little more. 12, 14, 16 will interchange but aren't balanced the same, can probably find some on-line resource to help you tell which is which. Been so long since I've worried about it that I forget. Some have flattened off counterweights etc..
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