This service repair manual covers the Mercury Mariner 40 HP Sea Pro outboard motor, identified by serial number 0G044027 and above. This water-cooled, 2-cylinder engine delivers 40 horsepower and features a carbureted fuel system and an outboard gearcase drivetrain. Designed for reliable performance on the water, the Mariner 40 HP Sea Pro is engineered for durability and efficiency, making it a capable choice for various marine applications. This manual provides comprehensive guidance for the maintenance, repair, and technical understanding of your Mercury Mariner 40 HP Sea Pro outboard motor. It details essential procedures, including recommended fluids, lubrication, fuel requirements, and routine service intervals. This resource is intended to assist owners, mechanics, and technicians in ensuring the optimal performance, longevity, and safe operation of the engine.