Craftsman, Kohler MV18S, ignition magnets weak, no spark.

tom3 · Jul 26, 2021

Old GT5000 Sears Craftsman riding mower. Like this old machine, like the sound of that Kohler twin. Engine MV18S flathead opposed 18hp twin. Mowing the other day, engine started to sound off a bit. Got done, blew it off, filled with gas, no start. Took a while but figured out no fire at the plugs, ignition magnets on the flywheel are pretty weak. Tightened up the coil gap and it started and runs. Probably not for long. Is it possible to replace those two magnets, maybe remagnetize them? Or is there a battery powered ignition setup that could be put in place of the old magneto type system? Have done this with a points ignition on an old Gravely, not sure with this ignition. See some used flywheels on Ebay, might be no better than what I have. Any suggestions?

Roadworthy · Jul 27, 2021

I read somewhere that some oxidation can build up between the magnet and the pickup. You could try polishing with a fine sandpaper and checking the gap.

tom3 · Jul 27, 2021

I'll check on that. Also found a place that rebuilds old magnetos and they do restore magnets in the carrier on these Kohlers. That'll probably be the best fix for this. Thanks for the reply!

Richard001 · Jul 28, 2021

just out of curiosity, how do you know that the magnets are "weak" ?

Richard

tom3 · Jul 28, 2021

Tried the screwdriver pull in deal. Dangle a flat blade screwdriver beside the magnet, see how far away it will pull in. Couldn't find a spec. for Kohler but B&S specifies 3/4 in for a strong magnet. These barely pull in at 1/4 in. And just by feel with a 1/2 in socket the magnet doesn't have much strength. Kohler manual says the magnet mount is not removable so sending that whole flywheel to get it re-magnetized might be a problem. I wonder if a couple non-resistor plugs might help some?

Richard001 · Jul 29, 2021

Found this thread on this forum:

Can you re-magnetize a flywheel magnet?

Hello, I recently got hooked on David Bradley 2 wheel tractors and my last purchase was a 917.57561 with a Continental AU8 engine. I am having problems keeping it running so I went over the carb, the points and condenser, the points are under the governor cap, and checked the flywheel. Now...

www.smokstak.com

One guy said that he got his magnets recharged by the engine manufacture.