mkazemi wrote:
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?


Doubtfull that the tap's made of cast iron, I've never heard of one. Why
are you "pretty sure" that it is? And, if it was cast iron the drill
bits should have gone through it like it was butter.

If the housing is off the car and you don't mind spending some time, you
can submerge the part with the busted tap in a boiling concentrated
solution of alum. You'll see bubble coming from the tap and in a while
it'll be eaten away, without damaging the aluminum.

Again if it's loose from the engine you could find a shop with EDM
eqiuipment and have them "burn" it out.

Which reminds me, about 40 years ago when I first learned about using
alum to remove broken taps from non ferrous materials I thought I could
get rich quick by selling alum packaged in cardboard cannisters as a
"magic" tap removing system. I named the product "Bust-Out" and had
labels printed up with a photo of a gal spilling out of her bathing suit
to put on the packages. It was the idea which was a bust, I didn't sell
enough of them to pay for the labels. G

Thanks for the mammaries,

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"