Heat exchanger for marine engine cooling system

A closed loop cooling system for an internal combustion engine in a marine propulsion system, comprising:

• a circulating pump for circulating the engine coolant throughout the engine;
• a thermostat assembly receiving a flow of engine coolant from the engine, the thermostat assembly having a thermostat and a thermostat housing, the housing having a bypass outlet and a thermostat outlet;
• and a
• a heat exchanger having;
• a heat exchanger body having a coolant flow path and a sea water flow path;
• a heat exchanger sea water supply inlet that connects the sea water flow path in the heat exchanger body to a supply of raw sea water;
• a heat exchanger coolant inlet that connects the coolant flow path to the thermostat outlet of the thermostat housing;
• a top tank integrally mounted to an exterior of the heat exchanger body, the top tank having a top tank coolant outlet;
• a top tank venting orifice in the heat exchanger body that allows air and coolant to flow from the coolant flow path in the heat exchanger body into the top tank;
• a heat exchanger sea water outlet that allows sea water to exit from the sea water flow path in the heat exchanger body;
• a heat exchanger coolant outlet that allows coolant to exit the coolant flow path in the heat exchanger body and flow to the circulating pump;
• a bypass inlet on the heat exchanger coolant outlet which connects the bypass outlet of the thermostat housing to the heat exchanger coolant outlet and allows coolant to selectively bypass the heat exchanger body;
• and
• an auxiliary inlet connected to the heat exchanger coolant outlet, the auxiliary inlet being in fluid communication with the top tank coolant outlet.