The Westerbeake circa 1985 has a direct mechanical drive no belt to this pump just to the alternator. When I removed the cover to check the impeller I had a friend bump the engine and it was turning. I figure the easiest thing to do next is remove the thermostate and run the engine. If it still overheats then I move to the heat exchanger which is much harder to get to and work on. I guess that is sound reasoning?
Cabo Rico 38