This manual covers the International Harvester B-250 and B-275 series tractors, renowned for their utility and reliability in agricultural applications. As a product of International Harvester, a historically significant American manufacturer of agricultural machinery, these tractors represent a key part of the mid-to-late 20th-century mechanization era. The B-250 and B-275 models were designed with robust engineering, intended for demanding work, and their enduring presence in the field speaks to their quality and durability. This service manual provides comprehensive information to ensure these machines continue to operate effectively. The purpose of this manual is to serve as an authoritative resource for the maintenance, repair, and servicing of International Harvester B-250 and B-275 tractors. It details a wide range of systems, including the engine, lubrication, cooling, fuel, clutch, transmission, drive chain, rear axle, brakes, front axle, steering, shock absorbers, bodywork, intake and exhaust, hydraulic, and electrical systems. Owners and mechanics will find step-by-step repair procedures, advanced troubleshooting guides, detailed illustrations, and crucial safety information, enabling efficient upkeep and problem resolution. The manual is designed to empower users to perform necessary tasks, potentially saving on labor costs while ensuring the longevity and optimal performance of their equipment.