Abstract: An exhaust manifold is for an outboard motor having an internal combustion engine. The exhaust manifold has an exhaust conduit that conveys exhaust gas from the internal combustion, and a cooling jacket on the exhaust conduit. The cooling jacket defines 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 is separate from the first and second cooling water passages and conveys spent cooling water from the internal combustion engine to a thermostat.

Abstract: A marine engine has a cylinder block having a plurality of cylinders. A cooling jacket is formed in the cylinder block and is configured to convey cooling fluid alongside the plurality of cylinders. The cooling jacket has a top end and a bottom end. A ledge is formed in the cylinder block. The ledge radially extends into cooling jacket at a location between the top end and the bottom end. A spacer is disposed in the cooling jacket and supported by the ledge so that the spacer remains spaced apart from the bottom end, thereby maintaining a lower cooling passage between the spacer and the bottom end.