Can anyone tell me what this is? --- Alpha 1 Gen 2 lower water pump assembly

[Walker600]

So when rebuilding my water pump assembly in the lower unit I noticed this small hole at the peak of the rounded edge of the impeller plate, (as per picture) the gasket sits underneath it but not as it is suspended in the air I can't Imagine it keeps a seal, it looks as tho it would allow water into the drive shaft assembly, surely that can't be the case.... What am i Missing?

Cheers

 

[ENSIGN]

Re: Can anyone tell me what this is? --- Alpha 1 Gen 2 lower water pump assembly

It's a drain to keep any water from freezing in the pump and drive