I am new to boating and have a cooling question about my 1962 40 hp. At low speed I have water flow through the engine but above 1/2 throttle no water comes outthe **** hole. When the motor is taken back down to a speed where the water is coming out the water is hot but not scalding and drops in temp in a few minutes. The water pump was serviced by a evinrude repair shop this year. Boat runs fine, just worried.