Need help. Engine temp will hold steady at 150 or so during high/full throttle. All of the sudden the temp gauge will go to 200 and engine will go into safety mode. It only takes about 2 seconds for temp to go up. Its like a switch is flipped it happens so fast. I can rev to 2000 rpm in neutral and it will cool off fairly quickly, but not as fast as it heats up. Sometimes after cruising at 3500 rpm for a long while it will get hot only after deplaning, and going to idle. Again, can rev to 2000 rpm and will cool down. I had an impeller come apart on me last season. I have changed impeller, thermostat, new o rings from drive to transom shield when I replaced gimball bearing. I have flushed, and backflushed all hoses .coolers and get good flow. Motor can run fine all day as long as rpm stay below 3500. Is it possible that piece of impeller is in the cooling passage ways in the motor? I have done everything I know of. I am about to pull the engine water pump and check for debris. Has anyone out there had a similar problem. By the way it is an open cooling system.
