Exhaust conduit cooling jacket and thermostat configuration for outboard motors

An exhaust manifold for an outboard motor having an internal combustion engine, the exhaust manifold comprising:

• an exhaust conduit that conveys exhaust gas from the internal combustion;
• a cooling jacket on the exhaust conduit, the cooling jacket defining a first cooling water passage that conveys cooling water in a first direction alongside the exhaust conduit, a second cooling water passage that conveys the cooling water from the first cooling water passage in an opposite, second direction alongside the exhaust conduit, and third cooling water passage that conveys spent cooling water from the internal combustion engine to a thermostat;
• wherein the first cooling water passage has an inlet that receives the cooling water from a cooling water pump, wherein the second cooling water passage has an outlet that discharges the cooling water from the cooling jacket, and wherein the third cooling water passage has an inlet that receives the spent cooling water from the internal combustion engine;
• a transition passage that connects the first and second cooling water passages and transitions the cooling water from the first direction to the second direction;
• and
• at least one turning vane that radially extends into the transition passage and divides the cooling water into separate flows through the transition passage.

An exhaust manifold for an outboard motor having an internal combustion engine, the exhaust manifold comprising:

• an exhaust conduit that conveys exhaust gas from the internal combustion;
• and
• a cooling jacket on the exhaust conduit, the cooling jacket defining a first cooling water passage that conveys cooling water in a first direction alongside the exhaust conduit, a second cooling water passage that conveys the cooling water from the first cooling water passage in an opposite, second direction alongside the exhaust conduit, and third cooling water passage that conveys spent cooling water from the internal combustion engine to a thermostat;
• wherein the first cooling water passage has an inlet that receives the cooling water from a cooling water pump, wherein the second cooling water passage has an outlet that discharges the cooling water from the cooling jacket, and wherein the third cooling water passage has an inlet that receives the spent cooling water from the internal combustion engine;
• a transition passage that connects the first and second cooling water passages and transitions the cooling water from the first direction to the second direction;
• and
• wherein the exhaust manifold extends along a vertical axis and wherein the first cooling water passage and second cooling water passage extend along the vertical axis, and wherein the transition passage extends transversely to the vertical axis.

An outboard motor comprising:

• an internal combustion engine;
• an exhaust manifold that conveys exhaust gas from the internal combustion engine;
• a cooling jacket on the exhaust conduit and configured to receive spent cooling water from the internal combustion engine;
• and
• a thermostat mounted on the exhaust manifold and configured to discharge spent cooling water from the cooling jacket;
• wherein the internal combustion engine comprises a cylinder block and wherein the exhaust manifold is mounted on the cylinder block.

A cooling system for a marine engine, the cooling system comprising:

• a cooling circuit that discharges spent cooling water from the marine engine;
• an exhaust conduit that conveys exhaust gas from the marine engine;
• a cooling jacket on the exhaust conduit, wherein the cooling jacket is configured to receive spent cooling water from the marine engine;
• a thermostat configured to discharge the spent cooling water from the cooling jacket;
• a pump that pumps the spent cooling water through the marine engine and into the cooling jacket on the exhaust conduit;
• and
• a second pump that pumps another flow of cooling water into the cooling jacket and alongside the exhaust conduit.