See full version: What causes an ignition coil to overheat
An ignition coil will get warm in use but it should not burn you or be too hot to touch. If the system has a ballast resistor then check the voltage supply to the coil + terminal with the engine cranking and then with the engine running.
In this manner, what causes a coil pack to melt? here
Additionally, can bad coil pack cause overheating? no. if anything, that cylinder is running cooler and will act as a heat sink to disperse some of the heat. however, a misfire could be caused by a faulty headgasket, which could be the cause of an overheating condition. Can a bad coil pack cause the car to overheat? more
Had a run to a friends just over an hour and half away.
When I came out to leave it would not start, the coil was covered in oil so we swapped to another new still boxed coil.
On the way home I came to a stop three times, missfire then die,
You could feel the heat from the coil and it was too hot to touch, after about 30 minutes when cooled down the engine would start and run OK for another few miles and then it would die and a hot coil.
So that would imply that if yours is a 1.5ohm coil, it expects to be run through a ballast to give it around 6v during normal running, and often a bit more during cranking if your starter supports it. If the coil is generally good, a ballast resistor in series might be a quick way to sort it out. here
Last Sundays problems pointed to Condenser, turned out to be an electric fuel cut off switch.
Which coil should I use if my car has a ballast resistor? here
Ballast ignition systems were introduced in around 1970. To find out for sure, use a multimeter to check the voltage on the positive wire of the coil with the ignition on. more
Once the engine is running, the 12v feed is cut and the coil continues to run on the 9v feed.
A standard coil should read around 3 Ohms or around 12 volts more
(maximum 3.4 Ohms is ideal for our systems) more
Isolating the problem by excluding heat transfer from the engine, bad grounding and + feeding, bad condenser or break points, what other things could cause this? here
I have got in the past ignition coil overheating, making the engine run very erratically and in some cases it even wouldn't run at all until the coil got cooler. In one occasion I changed the coil for a new one and it overheated as well. more
I have read about: wrong timing, wrong spark plug gaps, dirty spark plugs (not in my case), poor fuel/air mix.