Universal parts and problems

got a 11 HP model 15(sea cooled). Ran with water valve closed. ate up impeller. Replaced and removed the thermostat. hooked up fresh water after pump, Seems to cool OK, this way. Removed exaust manifold.Need to replace.(new one $500)
Questions: 1. How big a stream should come out from the pump? 2.Is there anything past the manifold that would restrict the water flow? (Im not getting much water going overboard.) The manifold is not stopped up. 3. Where does everybody go to buy universal parts??
Thanks
Chuck

You may have pieces of the impeller in the hoses or passages restricting water flow. I have had this on my mastercraft before where the outlet of the pump is restricted by impeller pieces after an impeller crumbles.