Originally Posted by markiehd
well, idled fine, but temp started creeping up under load. Now i am caustios, and when it hit 180 i just idled after that, keeping the temp at 160. I have an automobile tstat from autozone in it.. are the marine ones different. im thinking new tstat and impeller, not sure what else it could be. my boat always ran around 140 before problems started...
Check the cover on the thermostat and the thermostat itself, especially if you ever noticed that the impeller lost one or more of its vanes.
How old is the impeller? When you change it, change the gasket, too.