I had to replace the rubber impeller since I forgot to turn the garden hose on when I started the engine to check the boat out for this summer. Most of the impeller blades were broken off and gone. I found half of one in the thermostat housing and 2 in the boat bottome under the engine. The engine does NOT overheat with the new impeller, but I do not get any water exhaust coming out of the center of the prop. I ran the engine for over 20 mins (prop engaged) watching the temp gauge go up to 180 and then back down to 160 several times. Do I need to worry about the exhaust situation? Where is the water going? Where should I look next for the broken rubber impeller blades?