This manual covers the International Harvester 786, 886, 986, and 1086 tractor models, likely produced from the late 1970s into the mid-1980s. These diesel-powered tractors, known for their robust construction and reliability, were a significant part of International Harvester's legacy in agricultural machinery. They offered a range of horsepower, from approximately 70 HP on the 786 to over 120 HP on the 1086, and featured various transmission options including gear and powershift configurations. Designed for demanding farm work, these tractors are characterized by their durable build and straightforward engineering, making them a valuable asset for farm owners and operators. This comprehensive service repair manual provides extensive coverage of all major tractor systems. It details engine service and repair, including disassembly, assembly, and overhaul procedures for the diesel engines. Transmission service, covering both mechanical and powershift types, is thoroughly explained. The manual also includes in-depth information on the brake, electrical, steering, cooling, fuel injection, hydraulic, and power take-off (PTO) systems. Furthermore, it offers guidance on general maintenance, periodic lubrication, troubleshooting, and component testing, empowering owners and technicians to effectively maintain, diagnose, and repair these International Harvester tractors.