How do I remove a broken spark plug from the lead end of a W124 103 engine (1992 260E)? The plug is broken halfway through the ceramic. I can get the engine-side of the plug out but not the lead end. Is it possible to undo the metal boot? I notice it has a wire ring around it and several lugs.

Meanwhile I've ordered new leads and Beru plugs BUT I'd really like to whack a new plug in right now. It looks like its had this problem for awhile. The plugs Haven't been changed for 4 years and I notice there's a small hole (pitting) at the base of the plug hole near the head. Possibly from arking.

Amazingly, even though the spark-plug is broken in two the engine fires without a miss and the car drives fine.

Since you have new plugs / wires coming, leave it go. The boot is holding the plug together. Extracting the plug and damaging the boot will leave you with a non running car. ( Driving with a dead miss will cook the cat converter. )

I'm worried the parts won't be here in time. I'm driving to the snow in one week. 1200k round trip. No way I'm doing that with a broken plug.

Needle nose pliers might work. Look at your other old spark plug tops, do they have a threaded or barbed end? If threaded, turning the broken insulator CCW might be easier then pulling.

If you puncture the boot, it will create a spark leak and a dead miss.

I managed to do it. I carefully undid the metallic sleeve...which revealed the rubber boot - with a bad crack in it. I managed to extract the broken top of the plug...and tape it up with electrical insulation tape. I refitted the metal sleeve...whacked in a new plug...and already I can feel the difference.Hopefully the new leads will arrive before I go on vacation.