ceramic piece off coil

I was wondering what the ceramic piece connected to the coil does and if they wear out on a Farmall 140

If your tractor is 12v, that is likely a ballast resistor, used to reduce voltage to the igntion to 6v. They don't really "wear out" but they can fail.

If its maybe 1/2 square by 2 1/2 inches or so long (often dull white or grayish) with a wire terminal on each end, one to the coil one from ign switch, and if its a 12 volt tractor that uses a coil designed for 6 volt operation, I agree with Scotty, its a voltage dropping (12 to 6) Ballast Resistor. They can go bad, usually by opening, use an ohm meter to test its resistance and continuity between its termnals with all else removed and it should be in the vicinity of 1 to 2 ohms or so. IF ITS AN OPEN CIRCUIT ITS BADDDDDDDD.

If it is a ballast resistor and its good you can turn the ignition on and use a voltmeter and if the points are closed Id expect near battery voltage on its input (from ign switch) but more like 5 to 7 volts on its output (to coil).

If its NOT an ignition ballast it may be some sort of insulator or wire holder device assuming its NOT something thats broke loose from the coil or distributor.....

A 12 volt tractor often typically uses EITHER a coil designed for use at 12 volts (some call them internally ballasted) OR SOME OTHERS use a coil designed for use at 6 volts and an external series voltage droping (12 to 6) ballast resistor. If you apply 12 volts to a coil that is designed to operate only at 6 volts, it may overheat because it doesnt dissipate the heat generated from the current that would pass throught it if a full 12 volts (twice its design) were applied.

Hope this helps

Best wishes and Happy New Year

John T

Thanks, wondered how that 12volt six volt worked. Tractor had been working fine, but stalled it plowing snow and it will not start gas is o.k. seems to be getting power to the ballist resistor but i don't have a voltmeter. it has new wires and plugs. Will have to borrow a voltmeter and check it and coil, points and condenser.Is there a coil off a car that will fit that tractor. Thanks again Kerry

You can replace BOTH resistor and coil with a NAPA IC14SB. (No resistor required).
You can replace JUST the coil with a NAPA IC13 (keep the resistor).
You can replace JUST the resistor with a NAPA ICR13.

I recommend option 1; it's about $19. (if coil is indeed the problem).

http://www.napaonline.com/Search/Results.aspx?Ntt=ic14sb&Ntk=Keyword&Nty=1&N=0

I find that winter ignition cut-outs are frequently due to moisture in distributor; I recommend you try another cap (NAPA IH350) and rotor (NAPA IH300) before anything else. If it does not solve the problem, you will have them as spares for when they DO go, or to use at next tune-up.

I am NOT affiliated with NAPA, but they have a store 3 miles away and CIH is 20 miles.