my 305 chevy inboard seized up tight last weekend in the bay. I maintain it religiously, flush with fresh water every time it is in sea water, change oil every time I use it,I replaced the 90's last fall because of a overheating problem( that fixed the overheating). I ran the motor since replacing the 90's outboard pump, and thermostat at least 20 hours and thought everything was fine, then at full throttle last week without any strange noises or knocks the motor just quit and would not restart or turn over. The temp showed a 200 degreeswhen it quit, because I was running full throttle with 9 people onboard(good load), but I don't know why it locked up. The previous owner also replaced the motor when the boat was 7 years old.That new motor was now eight years old. Could the oil pump have quit? 
