For the life of me I cannot figure out why he would do that?
I have seen some work out in the field where a person may have a small hole and rather than fix it, they drill it out to make it bigger and put a sort of plug in. I have not seen this with engines mind you, but it is not uncommon when you just need to fill a hole easily. Maybe this is what he was doing?
Anyway, I think I will continue to attempt to fix this hole while looking for a new pan.
