This worked for me, and only cost 1$. Used a 5/16 1 inch long roll pin. Remove old pump, if the broken stud in not flush with the mating surface, flush it, being carful not to damage surface. Clean the old gasket from the water pump. Support the under side of the pump on 1x2 blocks so the impeller does not hit, this will form a level surface to in-large the broken stud hole to 5/16". Drill press works the best. Then the roll pin will slide into the 5/16 hole. Bolt the water pump back on the front cover with at least 2 bolts. insert a 3/16 drill bit into the hole in the roll pin, it just fits, and drill out the broken threads. the 1/4-20 tap, need about one larger drill size to tap, but it is easy to in-large the hole, the initial pilot hole is the difficult one, with a steel bolt and alu cover. It worked for me.
Nice trick. Beats spending the 80 bucks on the snap on kit that still won't work as well as what you did.
OH YES! Glad that i saw this (again). Had a steel 1/4" bolt break off the head, naturally. This idea is even better if you have a failed water pump for a core!
Good idea, I use that method myself if I can't get a welder to it,or no welder available . Recently on ford 4.6l 2v thermostat bolts. Last buick 455 was for my shop truck and I welded nuts to those and 99% of broken bolts I encounter.
