depending ont he size shape and location of the hole
i would drill it out to a clean round hole and tap it
put a socket cap set screw in it with soem loctite to seal it up with
if you use an old half worn out tap it will be a night tight fit between the threads
or use a pipe tap and tap it for say a 1/8 inch pipe plug
i dont see why this wouldnt work just fine depending ont he location of the hole