Hello
I have a broken tap in a 1993 chevy lumina water pump housing. the
housing is aluminum but i dont know what grade it is. i am pretty sure
that the tap is cast iron but im not 100% sure. the tap is broken off
right at the base of the housing and i have tried cobalt drill bits and
they didnt work. the drill bits stated that they will work on armor
plate, but i gues they were wrong, being that they didnt work in
removing cast iron. I was wondering how i should remove the tap, would
a diomnd bit help or is there some chemical that i could use?