This manual covers the Yanmar 6LY2-STE, 6LY2A-STP, and 6LYA-STP marine diesel engines. These engines are known for their robust construction and reliable performance, featuring a 6-cylinder, 6.5-liter displacement. The STE and STP models are turbocharged and intercooled, offering power outputs up to 440 mhp, while the 6LYA-STP provides up to 400 mhp. Designed for demanding marine applications, these engines integrate advanced electronic fuel injection for efficiency and responsiveness. The purpose of this comprehensive Service Repair Manual is to provide essential information for the maintenance and repair of your Yanmar marine diesel engine. It details procedures for general inspection, fuel injection systems, turbocharger operation, lubrication, and cooling systems. The manual also includes disassembly and reassembly instructions, along with extensive troubleshooting guidance, ensuring that owners, mechanics, and technicians can effectively maintain the engine's optimal performance and longevity.