Coil getting hot, why?

G

GeordieP6

New Member
Hi,
I have a 1976 2200SC & the coil is getting very hot. Can anyone tell me if I should have a ballast resisted coil or not? One supplier tells me it should be a non ballast coil & another is telling me it should be a ballast coil. Help!! If I do have a ballast resistor on my car whereabouts is it fitted so I can physically check? Thanks

PS - There are 2 wires going to the positive on the coil that go into the same spade connector - looks like factory wiring not aftermarket, is this correct? Thanks
 
You should have a ballasted coil. The resistor is actually a length of wire, it's on the RH side of the engine compartment and is coloured white with a pink tracer if I recall correctly. You can check if it's there by measuring the voltage at the + terminal of the coil with the ignition on. It should be about 7 volts if there's a resistor, 12 if not. Of the two wires on the coil, one is from the ballast resistor and the other from an auxiliary contact on the starter motor to apply 12 volts and by-pass the ballast when the starter is operating.
 
Ok great thanks. I do have a ballasted coil fitted which is correct then. Any idea why it would be getting hot? Its a new coil. It is connected properly i.e. not wrong way round!
 
Have you checked whether the resistance is present? If you're applying 12 volts all the time to a ballasted coil then it will get hot.
 
No, I will check if the ballast resistor is there and if so if there is resistance. If it's not then I guess its ok to fit a non ballasted coil? What's the actual point in the ballast resistor anyway?
 
The ballasted system is for improved starting. You get 12v through a 9v coil when cranking to boost the spark. If you have a permanent ignition controlled 12v at the coil and that's causing your problem, you can either fit a 12v coil and see how you find starting afterwards, or fit an early type porcelain ballast resistor into the supply and keep the coil you've got.
 
scratching my head on difficult to start 1967 2000TC HOT579E. Think the coil is suspect.
Seems Likely I need the negative earth ballast type coil - will any type do the trick? Will go out and look for the ballast resistor.

did not see ballast resistor
Did find 12v on the coil. Weirdly the 12v is coming out of uninsulated spade connector. Suspect my own bodged repair!
 
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How are you measuring "getting hot". If you leave the ignition on without the engine running it will get hot, that's the nature of inductors - they oppose changes in current, in a steady state condition the impedance goes to nothing and you have a constant 6 amps pumping through the coil. It should be only warm with the engine running.
 
The hot coil issue was in 2016. The revival is now about hard starting by Rob.

I don't think a 67 car would have a ballasted coil.

Yours
Vern
 
The resistance on a non ballasted coil should 3 ohms across the low tension terminals. Check your points gap if that checks out as a closed up gap can over charge a coil of its aging.
 
Sorry for ancient thread resurrection and any confusion.
want to diagnose my starting issues.
hoped to positively identify the correct coil. Mainly as it’s an easy swap!
We have fuel
Engine does turn over, albeit sluggish.
 
If your engine is turning over sluggishly, sort that first. A slow turning engine will always be difficult.
 
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