A thermostat regulates the temperature of the water for engine cooling and keeps pressure in the cooling system to facilitate heat transfer from the heads and the cylinder walls. As the waxy mixture expands from water heating up, it pushes upward on the piston attached to the bottom of the thermostat valve.Click to see full answer. Also, what happens when you run a boat without a thermostat?You can run no thermostat but Will cause your motor to make oil ,if in the winter it Will cause the engine too sweat . Will affect how your auto choke works and your warm up will be longer . Will be harder to tune both engines to run the same.Furthermore, how does a thermostat work? At its core, a thermostat is simply the controls used to regulate temperature in a heating system. You can set a preferred temperature, and the thermostat works to keep your room or boiler at this desired level. If the home starts to drop in temperature, a thermostat switches the heating on to warm it up. Furthermore, can outboard run without thermostat? Yes, you can temporarily run your outboard without the thermostat and not harm the engine. No, you can not remove the thermostat and continue running the engine for long periods of time without causing harm to the engine. Here is a brief breakdown on why the thermostat is so important.Does a boat motor need a thermostat?Thermostat. One of the least appreciated components of an outboard motor is the lowly thermostat. A thermostat regulates the temperature of the water for engine cooling and keeps pressure in the cooling system to facilitate heat transfer from the heads and the cylinder walls.