High temperature exhaust systems for marine propulsion devices

An exhaust system for a marine propulsion device comprising an internal combustion engine and a driveshaft housing, the exhaust system comprising:

• an exhaust manifold that conveys exhaust gas from the internal combustion engine, the exhaust manifold having a downstream end with an outer surface;
• a first exhaust conduit that conveys the exhaust gas from the exhaust manifold, the first exhaust conduit having an upstream end and a downstream end each having an outer surface;
• a first flexible coupler having an outer surface and an inner surface, the first flexible coupler coupling the downstream end of the exhaust manifold and the upstream end of the first exhaust conduit such that a gap is retained between the downstream end of the exhaust manifold and the upstream end of the first exhaust conduit;
• a first metallic coil coaxially aligned with the first flexible coupler, wherein the first flexible coupler biases the first metallic coil into contact with both the outer surface of the exhaust manifold and the outer surface of the first exhaust conduit;
• a first clamp engaging the outer surface of the first flexible coupler such that the inner surface of the first flexible coupler sealingly engages with the outer surface of the exhaust manifold;
• a second clamp engaging the outer surface of the first flexible coupler such that the inner surface of the first flexible coupler sealingly engages with the outer surface of the first exhaust conduit;
• a second exhaust conduit that conveys the exhaust gas between the first exhaust conduit and the driveshaft housing, the second exhaust conduit having an upstream end with an outer surface;
• a second flexible coupler having an outer surface and an inner surface, the second flexible coupler coupling the downstream end of the first exhaust conduit and the upstream end of the second exhaust conduit such that a gap is retained between the downstream end of the first exhaust conduit and the upstream end of the second exhaust conduit;
• a second metallic coil coaxially aligned with the second flexible coupler, wherein the second flexible coupler biases the second metallic coil into contact with both the outer surface of the first exhaust conduit and the outer surface of the second exhaust conduit;
• a third clamp engaging the outer surface of the second flexible coupler such that the inner surface of the second flexible coupler sealingly engages with the outer surface of the first exhaust conduit;
• and
• a fourth clamp engaging the outer surface of the second flexible coupler such that the inner surface of the second flexible coupler sealingly engages with the outer surface of the second exhaust conduit;
• wherein the first metallic coil is configured such that when in contact with both the outer surface of the exhaust manifold and the outer surface of the first exhaust conduct, the first metallic coil shields the first flexible coupler from the exhaust gas and also conducts heat between the exhaust manifold and the first exhaust conduit;
• and
• wherein the second metallic coil is configured such that when in contact with both the outer surface of the first exhaust conduit and the outer surface of the second exhaust conduct, the second metallic coil shields the second flexible coupler from the exhaust gas and also conducts heat between the first exhaust conduit and the second exhaust conduit.