Just finished the following repairs to a Universal 5411 diesel on my 1980 Catalina 30. New oil sender, old one was leaking oil. New gaskets on manifold. installed a thermostat 140F because there was not one. Replaced temp sender. replaced old exhaust riser with new one. Tested the engine on the lake and now have steam coming from exhaust. Temp gauge shows temp at 140 to 150 F. Can anyone tell me why I have steam coming out the exhaust?