Exactly how does a bad sparkplug wire, or a bad boot, blow out the ceramic insulator of a plug ? The spark travels from the coil to the top of the plug. If the plug isn't bad, as in new, how does the insulator break ? I just can't quite picture this in my mind. My new wires seem to have, for now at least, stopped my plug breakage problem. But the dealer said there was no way an engine can break an insulator, and I buy that, since I can't imagine how it would happen. So for the sake of my sanity, does anyone know how this works ? There have been others in here with broken insulators, so it's not a real uncommon problem. Thanks y'all.

Ken, 99 Silver Frost SE Zetec Atx, polished alloys, Kumho's, Pioneer hi power CD/AM/FM. Factory spoiler (added) Audi side lites, Borla stainless steel muff. Stolen, recovered in pieces. Looking for another Tour, preferably V6, 5 speed.