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Discussion Starter #1
3 coils later, I still have no spark. Original coil, which had weak spark before, now has none. My known good replacement coil acts like it's dead now, too. I bought a 129$ Kohler OEM replacement coil and still no spark.
The kill wire isn't connected.
Both plugs are in, with their wires connected.
Coil magnet is gapped to .014", per spec.
Spark plugs are correct and gapped to .035, per spec.


I did notice after shining the flywheel magnet that its cracked, it's a crack halfway down the long red line then goes into a deep scratch, and has a chunk taken out of it (which can be seen at the top of the picture). I checked out the original coil, and the edge is dented and folded over, so it seems like the coil was set crooked and the flywheel magnet hit the coil.

Does this mean I'm screwed? This flywheel was way over-torqued and bent my puller trying to get it off, so it's on there wayyy too tight, the bolt is on there with over 100 ft/lbs of torque, which warped the bolt head.
 

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In 2nd picture the kill wire is connected.
I always just removed spark plug (easy turning motor), then turned flywheel until lines up with coil. I put a business card between the two, tightened coil screws snug. Turn flywheel to be sure it clears all way around. Plug into coil, plug on side grounded to motor. No kill wire on coil. Cranking should see a good spark.
Otherwise sounds like you'll need to replace flywheel. I use a little penetrating oil, gentle puller pressure, rap flywheel with hammer. It should pop right off.


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"turned flywheel until lines up with coil."
Should say...turned flywheel until MAGNET lines up with coil.

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Discussion Starter #4
Yeah, it's so stuck on there it bent my puller. It's on there tight. Don't know if I can even get it off.
 

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Mudrig 150,

Is it possible that the "Impact" that caused the Chipping & Crack on the Flywheel "may have" knocked the Magnetic Field off?

It is a Very Good Possibility...

As for removal, mix a 1:1 Ratio of ATF & Gasoline in a SEALED Container, and allow it to soak for 23hrs. As the Fuel will evaporate, make sure to seal after applying and Label after/before use. This stuff works!

Take care,
-Thomas (12)
Western Washington State

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Hopefully you'll get better answers, but I would have the flywheel nut at top, so it's threaded on flush with top threads.
Then wedge wood strips bottom flywheel to block so pressure is flywheel up (off). All around even pressure. Penetrating oil. Then rap nut with hammer. If it's frozen solid some heat may help.

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Did you check the coil windings for good resistance per the manual? It might be all the problem you have.. Check the kill wire to ground and make sure your points are not grounded directly but through the condenser (if you have points).

I know folks discourage this but if I get a toughie like that I'll take a MAPP torch and heat up the area around the flywheel-to-crank area with the puller on and @ a goodly pressure applied.. Not a ton of heat, just enough to expand things.. The flywheel will pop right off.. Good luck!
 

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Discussion Starter #9
Did you check the coil windings for good resistance per the manual? It might be all the problem you have.. Check the kill wire to ground and make sure your points are not grounded directly but through the condenser (if you have points).

I know folks discourage this but if I get a toughie like that I'll take a MAPP torch and heat up the area around the flywheel-to-crank area with the puller on and @ a goodly pressure applied.. Not a ton of heat, just enough to expand things.. The flywheel will pop right off.. Good luck!
Worst part is the only torch we have with gas in it is the high heat torch, which doesn't go low enough to just warm up, at its lowest setting it likes to warp flywheels and cranks.
My puller bent and the crowbar I was using to pop the sucker loose bent, too. And that was with enough heat to discolor the crank end.
This flywheel is not coming off, and I don't think it ever will. I would have to smash the flywheel to get it off.
The only spare flywheel I have, the other M18 flywheel, is cracked where it goes on the shaft. The M20 flywheel is missing entirely. Guess I'm SOL.
 

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See if you can find a used flywheel somewhere and beat the **** out of the one you have to get it off. Just dont gak the crank threads. What does your puller look like? Some are flimsier than others and I've bent some of those flimsy ones. Do you have an air hammer handy?
 

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Discussion Starter #11
Sanded and polished the magnet, set to .008" and still nothing. Busted a pry bar in half trying to pop the flywheel loose. I'm done with this engine. :mad:?
 

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I'd say your cracked magnet is what's keeping it from sparking. That effectively makes 2 partial strength magnetic fields where the pickup is looking for one stronger signal.

I happen to have a rebuildable M18 I just pulled out of a Cub I'm repowering with an Onan if you're anywhere near NE Ohio.

Put the crank nut on the flywheel so it's flush with the tip of the crank and while you're prying up (or wedging the FW) give it a serious wallop - I hold a 2" brass chunk on there just to keep from bending the nut/threads.
 

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Discussion Starter #13
Welp. My puller is ruined. Added some bracing after bending it back, put all 4 driveshaft bolts on, and tightended the threaded part of the puller over 50 ft/lbs. The thing was bending up in the middle, it was that tight. Gave it a hit with the hammer, and the threaded rod broke in half. Someone must've used a hydraulic press to put this **** flywheel on!!!!!!
 

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Discussion Starter #14
I still don't understand how it had spark before we picked it up and now nothing???

I got it with a fuel issue, it ran when you dumped gas down the carb, and had a bad fuel pump.
We got the snapper home, tested spark after unloading it from the trailer. Good spark.
Key switch put 12 volts to the ground wire. Weak spark. Unplugged the coil kill wire.
Pulled the engine to fix the starter. No spark.
Pulled engine out entirely, and had it sitting on the floor. Weak spark.
Swapped it for my known good coil. Good coil completely lost spark even on another engine.
Put engine on table, swapped for BRAND NEW COIL, new coil has no spark. Can't test on other engine because I don't have the other engine.
It's set to .010, has no kill wire connected, and only goes on one way.

WHAT MORE COULD THIS ENGINE WANT????
 

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Discussion Starter #15
Coil tested good, got 28,000 OHMs. Sanded the bracket and did everything and got .8 OHMs resistance from the coil body to ground, so what's the issue???
 

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It's an extremely simple circuit. Here's the wiring diagram. One coil for two cylinders. With proper flywheel to coil gap it sparks as magnet goes past coil.
For spark test, the kill wire should not be connected (1/4" tab side of coil).
Sounds like with a cracked or weak magnet, flywheel has to be replaced. With broken threads, crank needs replacement.
Maybe a replacement motor (new, good used) may be the best choice.
A metal bar stuck on the magnet, and force it takes pulling it off compared with different flywheel magnets gives an idea of strength comparison.


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Coil tested good, got 28,000 OHMs. Sanded the bracket and did everything and got .8 OHMs resistance from the coil body to ground, so what's the issue???
8 ohms from coil body to ground. Where is the ground lead? I assume the motor block.
Zero meter by leads touched together. It should be zero ohms...1 ohm at most coil to motor (farther from coil resistance increases some).

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8 ohms from coil body to ground. Where is the ground lead? I assume the motor block.
Zero meter by leads touched together. It should be zero ohms...1 ohm at most coil to motor (farther from coil resistance increases some).

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Disregard I see it's .8 (8/10th) ohm. That's ok.

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