hole in water pump

I just bought a new impeller for my 69 roadrunner 383 water pump. the impeller housing has a 12-24 threaded hole at the 6 o-clock position. grease fittings don't fit. what is this hole for? If it was a bleed hole, why would they thread it? should I plug it or leave it open?

blake

Do not plug the hole

http://www.ehow.com/how-does_5187372_there-small-hole-water-pump_.html

No , don't plug it . Its supposed to be like that .

That would be a weep hole if the mechanical seal goes bad it leaks coolant there not shout why it is threaded

Thank you guys. I put it back in the car without plugging the hole.