Originally Posted by Tim R.
You could be running normally if you have a 180° thermostat installed.
That is the intelligent answer.
What thermostat is installed? If it is a 180°F then that's where the engine ought to run.
Most engines, marine or otherwise run at around 85°C (185°F, sorry I am metricated
) as controlled by their thermostats.
Closed circuit cooling systems can run hotter because they are pressurised and the boiling point of water is higher when under pressure. As a general statement, engines run more efficiently the hotter they run which is the primary reason for pressurised cooling systems. Raw water cooled engines will run on a cooler thermostat because there is no pressure but they should still run at the temperature regulated by the thermostat. Lesson over.
So if your engine is running at considerably less than 185° (or whatever the rating of your thermostat) then you should be concerned because it is less efficient and is probably experiencing accelerated wear. And your thermostat has either been removed or is stuck open.