I just reread your post – I was obviously thinking PRE war Sea King. The POST war horse and a half used a rubber rotor driven by an eccentric on the propeller shaft. Unfortunately the Oilite prop shaft bearing allowed some oil the seep into the pump housing causing the rubber rotor to swell. This increases it’s diameter and reduces the amount of water pumped. On the other hand, the water jacket on those motors consists of a loop of copper tubing wrapped around the grey iron sleeve as it is put into the die casting machine in Waukegan Illinois. Then some are sent to Milwaukee for Evinrude Sportsmen and some to Galesburg for various brands. They are resistant to corrosion but not from clogging. They can be cleared by reverse flushing. This illustration of a Johnson pump by Frank Robb shows what to look for in your Sea King. . . 😉
