Bite the bullet and pull the head;
Given the outer steel shell broke at the weakest point, the minor
diameter of the the threads, the likelihood you will have to repair the
threads is probable. You don't want pieces of steel from the old plug
threads sitting on top of the piston and creating hot spots or worse
like jamming a valve.. If you could manage to remove the remaining part
whole without drilling, you could re-tap the aluminum head and insert it
with a better chance of survival but still iffy. I just had the same
happen to my Miata and the cost by a competent mechanic with misc. was
900.00
Marcus Pryor wrote:
> I have a peculiar problem, and I would like some opinions from those who
> have walked the walk. The reason my '68 2000 doesn't run is because it has
> a broken spark plug. Here's the rub; it isn't broken at the usual place
> (at the base of the insulater) but, believe it or not, the iron base of
> the plug sheared off just above the threads!
>
> I have studied the problem with an eye toward removing it without pulling
> the head. I would like to see if I can get it running the way it is. I
> figure if I drill it out (best solution), I will get some detritus into
> the combustion chamber. Any thoughts before I tear her down?
>
> Marcus A. Pryor
> For a new age of reason
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