This service manual provides comprehensive guidance for the Yanmar 6LY2-STE, 6LY2A-STP, and 6LYA-STP models. These engines are engineered for robust performance and reliability, suitable for a variety of demanding applications. The manual details the quality construction and advanced systems that contribute to the operational excellence of these Yanmar marine diesel engines. The purpose of this manual is to equip owners, mechanics, and technicians with the necessary information for effective maintenance and repair. It covers essential areas including general information, inspection and servicing of basic engine parts, fuel injection, turbocharging, lubrication, cooling systems, reduction and reversing gears, remote control, and the electrical system. Detailed procedures for disassembly, reassembly, and troubleshooting are also included, ensuring that users can maintain their engines in optimal condition and address any issues efficiently.