This manual covers the YSE8 and YSE12 Marine Diesel Engines, renowned for their robust engineering and reliability in marine applications. Designed for dependable performance, these engines provide efficient power output, with the YSE8 delivering 8 horsepower and the YSE12 delivering 12 horsepower. Their durable construction and straightforward operation make them a preferred choice for various marine vessels, ensuring consistent functionality for owners and operators. This comprehensive Service Repair Workshop Manual provides essential information for the maintenance, repair, and servicing of your YSE8/YSE12 marine diesel engine. It includes detailed procedures for disassembly, reassembly, adjustments, and inspections, along with crucial technical specifications, troubleshooting guides, and wear limit data. The manual is presented in English and is designed to assist both experienced technicians and engine owners in keeping their engines in optimal working condition.