Maxxforce 13 question???

I have a 2013 Maxxforce 13 that we just rebuilt, new sleeves, pistons, ect. We are still getting water in the oil so we ordered new complete oil cooler. We left the pan off and started putting water in and it started pouring out water from the #1 hole. At first we thought we pinched an o ring but after looking more, it's coming out of the hole circled in the picture. Where does this hole go???