Ignition Coil Failure
Posted July 23, 2014 - 08:58 PM
Posted July 23, 2014 - 08:59 PM
Posted July 23, 2014 - 09:07 PM
Posted July 23, 2014 - 09:39 PM
I'd look at an overcharging issue like Neil sugested. The other thought would be that you are using the wrong coil. Some coils have an internal resistor and some don't but they look alike. Check the voltage at the positive post of your coil. If it is the same as battery voltage then you need a coil with an internal resistor. Otherwise, you need to put a resistor in the wire going to the coil something like the old balast resistor on a Chrysler product from the 80's-90's.
- boyscout862 and propane1 have said thanks
Posted July 23, 2014 - 09:39 PM
Posted July 23, 2014 - 09:45 PM
I think you may be getting bad coils out of the box.
Maybe Chinese made from the same store?
Or, your getting too much voltage to the coil, and that's causing the problem.
Can you use a known good coil from something else?
You might be better off with an old coil that you know is good.
Or buy a better coil from a different maker.
Posted July 24, 2014 - 07:27 AM
Too much current through the coil may be the culprit. If you have replaced the regulator you should not have a high voltage condition. However, you should check the connections in the charging circuit. A bad connection from the regulator to the - side of the battery will prevent the regulator from working properly.
Posted July 24, 2014 - 09:24 PM
Posted July 25, 2014 - 06:38 AM
With an internal resistor, I don't think you should need a second one if everything else is right. Where did you get the new coil, same place?
Posted July 26, 2014 - 07:36 AM
Posted July 26, 2014 - 08:02 AM
Yeah I got the coil from the Deere dealership where I work . Again it has a john deere part number stuck over top of a Kohler number in a Kohler box. I'm assuming it's an oem Kohler coil. What's a good way to check for a/c voltage?
If your battery is good you won't see much AC voltage on the top of the coil. Just put your meter on AC and proceed as if measuring a DC voltage. The alternator charging current is rectified AC which is filtered by the battery. When the battery is charging you should only see a small AC voltage, which represents the peaks of the AC current. The lower the impedance of your battery the less AC you will see. On the lower side of the coil, going to the points you will always see AC voltage when the engine is running. This is normal. The points are switching the coil current on and off. That is what generates the High voltage at the spark plug wire.
This must be a frustrating and expense problem for you. A few other things come to mind. Heat and vibration may be impacting the coils. If your engine is vibrating a lot due to loose or worn motor mounts or if it is running hot, these 2 things could impact coil life. If for some reason the power is not being disconnected from the coil when the tractor is turned off and the points are closed this will put a continuous DC current through your coil and over heat it, perhaps even burning it out if your battery lasts long enough. This may be worth checking. You should have 0 volts on the top of the coil when the ignition is off.
- Bruce Dorsi said thank you
Posted July 26, 2014 - 08:00 PM
Posted August 27, 2014 - 10:21 PM
- Rock farmer said thank you
Posted August 28, 2014 - 05:37 AM
Glad to hear you haven't had a coil go bad since last month . I forgot about this thread , thanks for the update . I wonder what different causes would make a coil run too hot or maybe they all run that hot ? How hot is too hot lol ?
Posted August 28, 2014 - 06:41 PM
Try making an aluminum fin heat-sink and clamping it to the coil.