Originally Posted by funola

For such a large gaping hole that is 1.25" deep all around in the intake, epoxy putty is not going to work. Below is what I'd propose. The 14-1.5 mm machined bolt's purpose is to apply pressure on the lead plug which pushes on the remnant of the glow plug, trying to do the same thing as when you tighten the glow plug. Whether this will work or not to keep combustion gas from escaping depends on whether the glow plug seat is intact and if sufficient, even pressure can be transferred to the glow plug seat.

The 1/4-20 N.C. set screw pushes on a rubber plug which seals the coolant breach. Coolant pressure is determined by your expansion tank cap, which should be around 17 psi max.