This workshop service repair manual covers Bolens models 1668, 1668L, 1669, 1669L, and 1858. These medium-frame tractors, likely produced in the late 1970s to early 1980s, are known for their durability and utility, reflecting the Bolens brand's heritage in American-made garden and lawn equipment. Designed for a variety of tasks, these tractors feature robust mechanical components, including air-cooled gasoline engines typically in the 16-18 HP range, manual gear transmissions, and 2WD drivetrains. The 'L' models may offer hydrostatic transmission variants. This manual provides comprehensive support for owners and mechanics looking to maintain and repair these reliable machines. The purpose of this manual is to provide detailed, step-by-step instructions for the maintenance, repair, and overhaul of all systems within the specified Bolens tractor models. It covers everything from routine service, such as oil changes and filter replacements, to complex procedures like engine rebuilding, transmission overhauls, and hydraulic system repairs. The manual includes diagnostic guides for troubleshooting common issues, detailed wiring diagrams for electrical systems, and specific adjustments for engine timing, carburetors, and brakes. Its comprehensive scope, presented in English and designed for easy use, empowers owners and technicians to perform necessary work efficiently, ensuring the longevity and optimal performance of their Bolens tractors.