Engine overheat after idling for about a minute. I checked the water pump. All the parts looked good. The guy who sold me the boat said he just put a new impeller in it. The impeller looked new. I checked the thermostat. It opened fully in a pan of water that I could stand to put my finger in for a second. I'm running the engine with muffs. No water comes from the tell / tell holes when its running. Could there be an obstuction somewhere?
