> > I have been told that spark erosion could be an option.
> No it is not, spark erosion can remove a broken bolt from a
casting that can
be put in the eroders oil filled tank..... there is NO WAY you
can get a car
in an eroder.
I agree that spark erosion is probably not an option, but you're wrong in assuming that spark erosion can only be done using a heavy floor standing m/c with an electrolytic filled tank etc. Years ago a Co I worked for had a very small spark eroder. Completely portable, and no bigger or heavier than a domestic food mixer. Specifically made for sparking out broken taps, bolts etc. I haven't seen another since, but for what it was designed for, it worked well. Could spark out the broken tap extractor as described with no problem, once the head was lined up to the hole.
All it consisted of, was a column mounted on a small base, with a 'woodpecker' head mounted on the column. The head had a lead to a small ECU which plugged into an ordinary mains socket. Water was added as an electrolite by any convenient method. Drip feed can, trickle from mains hose etc. Mike.