WC - Magneto?

Tom RS · Jul 5, 2017

Took some of our tractors out for a short road trip yesterday.
After a relatively easy start in the barn in the morning we stopped for some lunch.
Came out and as usual our 37 WC wouldn't start. This tractor has always been a pain when its warm to start - this is a crank only tractor.
HAd a tow strap so we pull started it - didn't want to start that way either but did get it going.
Drove it for about 5 minutes and it died again.
Then she wouldn't start and we towed it home.
Waited till it was cooled off for over 4 hrs and still wouldn't start.
Checked fuel supply - plenty.
This tractor appears to hve the original or a very old mag.
I'm thinking its time for a mag replacement.
Any other words of wisdom?

Thanks

Jerry Coulter · Jul 5, 2017

Sounds like the coil and/or condenser are failing. If it has the old Fairbanks Morse type RV mag, it is time for replacement. If you have the type FMJ4B3, parts are available and the mag should be serviced. Try to find a servicer who will recharge the magnetism in the rotor.

Butch(OH) · Jul 5, 2017

Sounds like you need to service the magneto or remove it and have it checked out. Procedures for checking the obvious things like the points varies with what magneto is on it so the next step is to let us in on what is on it. Some people can find their way through a magneto with a little help, other's should keep their fingers out of such things and send it off to a rebuiler you must make that call, LOL. As for the hot starting issue that is commonplace with a WC but the tractor will start much easier when warm if you kill it by shutting the fuel off and letting it run out instead of grounding the mag.

DGinVT · Jul 5, 2017

Send your magneto to John Brillman Co. John is an expert on rebuilding those. He has done 2 for me and they are perfect.

tractorguy2 · Jul 5, 2017

Fairbanks type J and are known for having bad coils. You can replace the coil yourself. I would also replace the points and condenser. I really doubt the magnet needs recharged. I buy and sell about 40 magnetos each year. I have never had a type J or X that didn't work very well with a new coil.

Look your distributor caps over good around the screw holes. Very common for them to be cracked. The large cap is very pricey. You may be better off to look for a different magneto.

old · Jul 5, 2017

Well if I still had my old computer I would offer to send you the manual for that mag but I lost hat info when my computer crashed on me. But maybe one of the guys I had sent that to will be kind enough to offer it to you. The manual will pretty much tell you every thing you need to know to fix the mag you have.

That said it could be as simple as the coil going bad or the points went bad or even the condenser which is the least likely but can happen. I have even seen rotors go bad out of the clear blue. But you might double check a few things like
#1 check for a good blue/white spark at the plug wires that jump a 1/4 inch gap or more. If you have that then your problem may not be the mag or if it is the mag it is likely to be a coil on it way out.

Ted in NE-OH · Jul 5, 2017

To test a magneto connect a timing light to each spark plug and see if the mag will trigger it. Harbor Freight has a $4.94 spark tester that you connect in series with the spark plug wire and you can watch the spark.

WC - Magneto?

Tom RS

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Jerry Coulter

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Butch(OH)

Well-known Member

DGinVT

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tractorguy2

Well-known Member

old

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Ted in NE-OH

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