A sealing member for a propeller shaft is provided with a heat shield to prevent damage from occurring to an elastomeric portion of the sealing member when exposed to hot exhaust gases. The exhaust gases can flow in thermal communication with the elastomeric portion of the sealing member when the marine propulsion unit is operated in reverse gear. A heat shield is provided by extending a metallic portion of the sealing structure toward the outer cylindrical surface of the propeller shaft and rounding the edge to avoid direct contact between the heat shield and the propeller shaft.