Honda B75K2-B75K3 Outboard Motors Manual., Page 12Get this manual
3COOLING SYSTEM The thermostat is located in the passage leading from the water jacket formed around the cylinders and operates (opens or closes), depending on the temperature of water returning from the engine, to maintain the water temperature within the limited rangeThere are two circuits from the pump outletWhen the engine is hot (thermostat open), water from the pump flows into the cylinder jacket, past the thermostat, into the cylinder head, and drains into the exhaust pipe to cool the exhaust systemSome excess water also flows out through the water check pipeWhen the engine is cold (thermostat closed), water from the pump flows through the bypass line (tube), through passage in the intake rnanifold, and drains both through the water check pipe and into the exhaust pipe-