New aluminum fan blade problem

[JayJay]

I have run into this problem on the last four water pumps I’ve handled. Oversized nose, and often the shaft is not centered in the nose of the casting. I created a jig that I mount the water pump to in my small lathe. I turn the nose of the water pump down to 1.640” and everything fits fine. Richard Knight nailed it - remove material from the nose of the pump housing.