I have a 1997 15hp Mercury 2-stroke outboard. When I run it it runs great and does what i want it to do. However, sometimes it doesn't pee. I can still hold my hand in the stream when it does but its very very hot. It always pees when i run the motor WOT but when im just chugging along it goes out for a bit and then comes back on. Is this supposed to happen? I was told by my dad that the thermostat regulates the pump so that it doesn't cool the engine down too much. Any and all advice is greatly appreciated
The telltale, or pee as you called it, should run all the time. It should never stop while the boat is running. You probably do need a new water pump, also called an impeller pump. I would not run this boat again until this is fixed or you could risk an overheat. The impeller is just a rubber or plastic blade, looks like a gear, that wears out over time. Every few years they should really be replaced although a lot of people don't change them until they act up.
The radiator actual holds the water/coolant and the pump circulates the combination in the process the engine. Upon returning to the radiator, the water is cooled from air passing in the path of the fins of the radiator. The pumps activity is to circulate the combination to confirm that the nice and cozy water to relax for this reason, the engine is then cooled.
Some Mercs only pee when the thermostat is open,especially the smaller ones.Trace the pee hose back to the engine.If it runs to the thermostat housing,it's one of those engines.
The telltale stream should be flowing all the time. Check if this engine has a termister and replace the imbeller
It should discharge water all the time. I would replace the water pump impeller every 2 to 3 years. In this case I think your getting intermittent flow. if the water discharge is steamy that would be a good sign you need to change the impeller.
