Would it be accessible to a MIG welder? If there are exposed threads, which there are given the question about JB Weld, my method of choice would be to weld a nut on the end of the broken bolt and use that to wind it out. If it's corroded in place the heat from the welding will also help break the grip of the corrosion.
TBH that would be my ideal, and what made me think of a welding glue. It's in a tricky spot to drill and gauge the right depth. Plus as it's an engine casing I don't want to get it wrong!
Would it be accessible to a MIG welder? If there are exposed threads, which there are given the question about JB Weld, my method of choice would be to weld a nut on the end of the broken bolt and use that to wind it out. If it's corroded in place the heat from the welding will also help break the grip of the corrosion.