My Beauty 1988 V12 has had new leads, plugs, distributor cap etc fitted and has been running like a new car. Yesterday it scared the crap out of me when I was out of the car and my wife yelled that there was smoke coming from the engine. I opened the bonnet and one of the HT leads was glowing with smoke coming off it. I freaked out and grabbed my fire extinguisher which stopped it. I had not been running the car long enough for it to get really hot. After about 5 minutes I started the car and it was OK to drive a short way home.

HELP is it safe to drive - what could have been the cause? Could the lead have been arcing to something. Now when I look I can't even see which lead it was. Any help would be terrific and very much appreciated.

Les

 

I can not see how a HT lead can get this hot and the engine remain running. The HT leads are also silicone insulated over 200°C rating. To get this hot the carbon conductor would have broken down and/or the coil fried.

I would look around and see if you can find another wire in the vicinity that has head damage.

 

Wouldn't the HT lead have to have an internal fracture to cause this? Would a damaged spark plug have a similar effect? More questions than answers..

 

I would take a careful look inside the dizzy. Somehow you had a dead short to earth, either from an external wire (as Doug mentioned) or from some odd fault inside the dizzy/coil.

 

thanks Warren, I guess I didn't think too much, just really worried - it was dark at the time and I couldn't see exactly what was smoldering - I have looked at all the wires in the vee and couldn't see any damage - I will have another good look around
Les

 

Do a simple resistance check of the plug wires

 

No this would cause an open circuit and no current to flow. To have a wire glow it needs to have very high current flow for the wire diameter. Like an electric heater element.

Current flow in a HT lead is on/off as the plugs fire, current enough to kill a HT lead would kill the coil first.

 

I would pull all the wiring ties and separate the wires, there will be damage somewhere when a wire smokes.

You're lucky it did not release ALL the smoke, we all know electronics/electrics work on smoke and when it's all gone it does not work any more................ Although in my experience these faults are much easier to find.

 

 

 

 

I'd keep the fire extinguisher with me at all times. That's real crazy that you can't find any damage??? As where there is Smoke, there is usually fire, and damage? Hope you find it.

Jack

 

A couple or more thoughts:

1. Heat in a wire usually means high resistance. Or a dead short to ground.

2. If it was/is a wire either HT or otherwise, I would expect signs of damaged insulation, burnt or melted.

3. As the symptom is gone, and all seems well, I suspect foreign matter that cooked and the engine fans blew the ashes away.

4. Try the engine in the dark and see if you get a TESLA like light show. Evicdence of leaking insulation

Carl