Abstract: Temperature control system for marine engine exhaust system. The control system lowers flow of cooling water to water jacket and exhaust gas conduit of the exhaust system at low engine speeds. The control system is typically activated at and below a predetermined engine speed. Once activated, the control system operates to reduce flow of cooling water to the exhaust system. The control can operate in an on/off mode, or can modulate rate of flow of water through the exhaust system, or both. However the water flow is limited, a predetermined minimum flow of cooling water is maintained through the exhaust system, at least either at periodic intervals, or at a constant but lowered rate, to maintain cooling in the exhaust system on rubber components of the exhaust system.

Abstract: Manifold pipe assemblies and exhaust manifold assemblies, optionally in combination with internal combustion engines, for receiving hot gases from such heat source, and conveying such hot gases from the heat source toward a lower temperature environment. Such manifold pipe assembly comprises a manifold pipe defining a gas path for conveying hot gases from an inlet end to an outlet end, a jacket pipe encompassing the manifold pipe along a portion of the length of the manifold pipe. The jacket pipe has a second inlet end disposed toward the inlet end of the manifold pipe, and a second outlet end disposed toward the outlet end of the manifold pipe. The jacket pipe is closed about the manifold pipe at the second inlet end, to form a closed cooling chamber between the manifold pipe and the jacket pipe. An inlet pipe conveys cooling liquid into the cooling chamber.