VC bolt seized

[rbodor3]

09 335, N54, 112k miles
Broke VC bolt between cyl 3 & 4 (over-torqued), below the head (nothing to grab with pliers). Tried to remove when an Easy-Out, but extractor broke inside the bolt (and couldn't remove). I RTV'd it up, but now (10 months later) oil is filling spark plug hole #3, causing misfire from coil #3. Looking for help on how to extract the bolt.

1. Pull head and replace, or drill - god please no
2. Oversize drill-out bolt, and helicoil - can I drill through the Chrome-Moly Easy-Out?
3. Weld a rod and nut - I only have a MIG, and am concerned the Chrome-Moly Easy-Out will pose a problem. Any advise? Also not sure how I can weld into the hole without damaging the surrounding head material. Any advise how this could be done in-chassis?
4. Some other solution that makes the coil pack robust to the oil, as a band-aid

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[White94RX]

Drill it out or replace the head. I bet you learned a difficult lesson. Maybe use a torque wrench next time.

[rbodor3]

Update for future searches:
The oil leak was not coming from the missing VC bolt (as diagnosed by Dealer). It's coming from the oil fill gasket - ordered a replacement (will update with results).

No oil was leaking anywhere near the missing VC bolt, which was near Cyl 5. RTV has held up well for about 6 months! We decided not to drill out the stuck bolt, with concern that messing with it (now) will do more damage then good. If it starts to leak, we'll revisit drilling.

I'm highly suspect the oil leak is causing misfire on cylinder 3, as BMW diagnosed. I'm weary of an intermittently faulty COP. That said, I could see oil filling enough of the spark plug bore to cause intermittent connection with the spark plug (seems unlikely). In any event, we've decided to fix the oil leak, then monitor for recurrence.

[Codes2]

Glad you found the source in a more definitive manner.
Good approach on correcting leak and then reevaluating the misfire.

I used to have half my sparkplug wells wet with oil until I corrected VCG and OFHG. So common it's a given effort at an age.