This workshop service manual covers the Mercury Mariner 40 Sea Pro, a 2-cylinder outboard gasoline engine delivering 40 horsepower. Designed for marine applications, this water-cooled engine features a reliable outboard lower unit transmission with forward, neutral, and reverse gears. Its robust engineering ensures dependable performance for a variety of boating needs. This comprehensive manual provides detailed information essential for the maintenance and repair of your Mercury Mariner 40 Sea Pro. It includes procedures for engine oil and gearcase oil changes, along with specifications for recommended oil types and capacities. Coverage extends to repair and overhaul, assuming the technician possesses a solid understanding of general automotive principles. This guide is an indispensable resource for owners and service professionals alike.