Thanks for the replies, gents. I think both of your theories have merit, especially given how close the water pump is to the powerhead. That said, the bailer-style pumps on the 33HP Scott-Atwater motors (with the bailer chamber stacked on top of the main impeller chamber) have a solid cover … i.e. no holes. So, if the water is meant to provide either cooling to the exhaust or keep the pump housing cool (being so close to the powerhead), I would have expected cover holes on the bailer-style pumps as well. As for the exhaust gases, maybe the double-stacked impellers on the bailer provide enough of a seal that the cover holes aren’t necessary on those, but needed on the single impeller pumps like mine?
