I am having problems with my 19 ft. Key West overheating when above 3800 RPM. When the problem started I purchased a Yamaha Water Pump kit and replaced it but the problem still not solved so I flushed the system good removed the heads and water jackets cleaned and replaced. Took it out and again the overheat alarm sounded at high rpm. I carefully watched the water flow and as I got to the higher speed I can see a reduction in the pressure coming out of the indicator. I have also cleaned the pop off valve and even tried without the thermostats. Any other suggestions??
