hot coil
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Mountain Pass
Joined: Mar 2006
Posts: 145
Likes: 2
hot coil
I was working on my 54 today and had key on for about 15 or 20 minutes. I went to cut key off and noticed coil (12 volts) was hot as a firecracker. I felt of the rest of the wiring (new original wiring harness) and it was not hot under the hood or inside truck What would cause the coil to get that hot with just the key on. Have it hooked up correct I think ignition side to plus side and distributor lead to minus side. Thanks
Elder User
Joined: Dec 2011
Posts: 701
Likes: 1
From: Echuca VIC Australia
What he said, I've seen coils fail after being left on also.
Lead Driver
Joined: Jul 2011
Posts: 6,599
Likes: 34
From: Rockingham, VA
The key is "the points are closed". Of course there's no way for you to know that with the cap on.
I did the same thing once on my Harley. Instead of a few minutes, mine was on for days. The coil was shot.
Hopefully, you caught yours in time to save the coil.
I did the same thing once on my Harley. Instead of a few minutes, mine was on for days. The coil was shot.
Hopefully, you caught yours in time to save the coil.
Believe Nothing
Joined: Jun 2004
Posts: 7,513
Likes: 394
From: W. Central FL.
Lead Driver
Joined: Jul 2011
Posts: 6,599
Likes: 34
From: Rockingham, VA
But you're right about our trucks.
Fleet Mechanic
Joined: Aug 2010
Posts: 1,994
Likes: 3
From: Morgan Hill, CA
I was told a long time ago that if you have a ballast resistor in the system, the resistor will heat up when the key is left on with the points closed. The resistance increases with heat and will eventually reduce the voltage to the coil to the point where it generally won't be damaged. It will still kill the battery after some time has passed.
As usual, all generalitys are false....so it probably won't work that way every time.
Dan
As usual, all generalitys are false....so it probably won't work that way every time.
Dan
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Fleet Owner
Joined: Jul 2004
Posts: 27,288
Likes: 1,053
From: NM
I was told a long time ago that if you have a ballast resistor in the system, the resistor will heat up when the key is left on with the points closed. The resistance increases with heat and will eventually reduce the voltage to the coil to the point where it generally won't be damaged. It will still kill the battery after some time has passed.
As usual, all generalitys are false....so it probably won't work that way every time.
Dan
As usual, all generalitys are false....so it probably won't work that way every time.
Dan
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Senior User
Joined: Dec 2003
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Mopars used "that" style, the porcelain block. Since these are easy to mount the Mopar design was real common on a 12 v conversion.
Ford used a ballast resistor wire for the ignition 56 up. Not sure what GM used.
Ford used a ballast resistor wire for the ignition 56 up. Not sure what GM used.
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