WAter pump question

Ok now I thought my water pump was the problem and it could still be but after closer inspetion it appears that there is a small hole on the top of the water pump ,like where a bolt or pin maybe went and has fallen out or got loose and fell out...now Im wandering whether or not that hole is there for a reason or is it in fact something that a pin came out of becuz that is where all the coolant is just spraying out of and I cant imagine why that would be there unless it had something plugging it before...any ideas ...Im just want to get the car drivable to trade it in and if I can plug a hole that isnt supposed to be there and thats th eproblem I d rather do that than replace the whole pump...any ideas????


thanks

There should be a type of spit valve there.
Yours is in better shape than mine, I have oil coming out of mine