This workshop service repair manual covers the Mercury Mariner Marathon outboard engine. While specific production years are not detailed, this engine is known for its robust construction and reliable performance, making it a dependable choice for various marine applications. Its 55 HP power output, delivered through a presumed 2-stroke outboard design, provides ample thrust for a range of boating needs. The engine features a water-cooled system and a standard outboard lower unit with forward, neutral, and reverse gears, ensuring efficient operation on the water. This comprehensive English-language manual is designed to assist owners, mechanics, and technicians in maintaining and repairing the Mercury Mariner Marathon. It provides detailed information on essential maintenance procedures, including service intervals and fluid capacities for the gearcase and oil injection system. Troubleshooting guidance, technical specifications, and safety recommendations are also included to ensure the engine operates at peak performance and longevity. The manual covers aspects such as the CD ignition system and trim system options, offering a complete resource for all service-related inquiries.