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Coil Getting hot

10468 Views 9 Replies 4 Participants Last post by  TerryS
Does anyone know if its ok for the ignition coil on my 2.5 petrol 90 to be getting hot :dunno: . Its almost too hot to touch. I've noticed this while fault finding my indicator problem..
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The Bosch coil, for whatever reason, seems to run hotter than the lucas coil, but even the Lucas coil runs hot. You should have a good look at your points (yeah, something the EFI people have forgotten) as they will run a higher rsesitance to ground if they are not maring up properly, or if they are partly burned.
A lot of people have opted to use a conventional coil (without the internal ballast resistor) and use an external ballast resistor.
Just the other week, I had a brand new Bosch coil puke it's guts out, all over the back end of my exhaust manifold. Engine wasn't running, but I was fault finding with the key on and the points were obviously closed.
Is the visible spark, at the plugs, a pure blue plasma, or are you seeing any yellow-orange color to it? Assuming it's a good quality blue spark, then I'm not certain your non-starting issue is related to the coil.
What's important to keep in mind when using aftermarket, externaly ballasted coils is that you have the correct ballast resister, so that you're not overheating the primary side of the coil. Most stock plug wires won't handle high intensity, 50K+ volt coil outputs, and normal compression Land Rover V8 engines don't get much added benfit from using these. I don't find any issue with using stock Lucas coils on these engines.
Sometimes it's worth just clearing the decks and getting back to basics. I believe the later Land Rover distributors which use Hall Effect pickup coils instead of points and condensers, and the correct 'amplifier' (a missnomer, as it's just an electronic switch to handle the coil primary circuit current) very reliable. Additionally, the firing pulse is very precise, as opposed to a the wider, less precise firing from mechanical points. If you don't have this distributor, with amp, you can probably get a good used one from Paul Grant.
The longer you try starting a nonfiring engine, the more likely you will foul even new plugs.
Other items to check are your cap and rotor. Rotors can frequently be cracked internally allowing a spark path through the center, to the distributor shaft.
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Trucks with external ballast resistors should have a 4 terminal solinoid. The two big ones are self explanatory, one from the the battery, the other to the starter. The two small terminals are: One which energizes the solinoid, from the key, and one which get 12+ when the solinoid is energized. That terminal is used to bypass the ballast resistor when cranking, to compensate for the voltage drop whil cranking. As you have a V8, I suspect you don't have that "hot only when cranking" terminal, since V8 starters have integral solinoids.
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