Replacing 225 water pump

The pump impeller (star wheel) is pressed on; you do not want to take it off as it would be about impossible to do with out damaging/destroying the impeller and will very likely cause big problems. I have worked sealant in the gaps for the outer layer before, but don't do that any more. I just put it on the block surface, and let the coolant swell up and seal the inner gasket; it may seep a bit.