This Service Repair Manual covers Mercury Mariner Outboard models including the 20Jet, 20, 25, 25 Marathon, and 25 Sea Pro, with serial numbers US 0G044027 and later. These 2-stroke, water-cooled engines offer 20 HP and 25 HP options and are designed for reliable performance on the water. The outboard lower unit drive system is engineered for efficient power transfer. This manual provides comprehensive guidance for maintenance and repair procedures. It details essential tasks to ensure optimal performance and longevity of your Mercury Mariner outboard. Owners, mechanics, and technicians will find detailed instructions and technical specifications necessary for effective servicing and troubleshooting.