CONTINUOUSWAVE

I've a 1990 Johnson 200 counter-rotating engine which hasn't been run in three years. It was running roughly and had always been a hard starter. I finally had time to remove the flywheel. Three magnets were shattered and the other three had broken free of the epoxy. The flywheel had also been rubbing against the stator so much so that the inside of the flywheel has gouges around the inner top. The potting from the stator has also melted out.

Has a stator ever swollen and deformed from over-heating or melting?

I am not quite sure why they would have been rubbing, other than that [the stator had swollen and deformed], unless the stator or flywheel wasn't seated properly. Thanks.

If there was mechanical interference between the rotating steel flywheel and the plastic molded wire bobbins that hold the copper wire coils of the stator in place, the mechanical interference would create abrasion. The abrasion would create heat. The heat would cause the thermo-plastic wire bobbins to become pliable. In that state there is a very good possibility that the thermo-plastic wire bobbins of the stator would deform. The wire insulation material is also subject to melting at high temperatures. A common insulating material is called FormVar. For more about the insulation used see

https://en.wikipedia.org/wiki/Formvar

and

https://en.wikipedia.org/wiki/Magnet_wire

I don't know the exact temperature at which cured Formvar becomes re-liquified.

Problems with the magnets embedded in pockets in the flywheel becoming loose are often due to splashing of water into the flywheel area. The water, particularly saltwater, causes rust and oxidation of the steel in the flywheel. The rust can result in the magnets becoming loose.

The abrasion of the flywheel against the stator assembly that was described above and the heat produced by it will soften the adhesive that is holding the magnets in place, also causing the magnets to become loose. Of course, as a result of the flywheel being located above the engine and the engine giving off a lot heat which rises, the normal operating temperature of the flywheel is going to be very warm. If the engine were to be running unusually hot, the flywheel temperatures will be correspondingly higher. Prolonged operation at higher than normal temperatures would also tend to have an effect on the adhesive holding the magnets into the pockets on the flywheel.

Once heat has cause deformation of the stator assembly and melting of the wire insulation, it will be unlikely that you can effect a proper repair. Replace the stator assembly.

You may be able to renovate and restore the flywheel. If you attempt this, be aware that the magnets have a North-South magnetic pole polarity and must be re-installed in the flywheel in the proper sequence and arrangement. Seek more details about this before undertaking the renovation of the flywheel yourself. Or, replace the flywheel with a new one or used one in better condition.

That the engine is a counter-rotation gear case model has no influence on the flywheel or stator. The direction of the engine rotation is the same in standard rotation and counter rotation models.

Speculation about the cause of the initial mechanical interference between the stator and flywheel may be interesting, but it won't affect the repairs necessary. The most likely initial cause of mechanical interference was a flywheel magnet becoming poorly adhered in its pocket in the flywheel. Problem of this type are common.

I recommend you examine the cooling water circulation system, hoses, thermostats, and fittings for any leaks. Water escaping from the cooling system can splash onto the flywheel and cause rusting.