This comprehensive Yanmar Marine Diesel Engine service and repair manual provides detailed instructions and diagrams for the 3JH2-(B)E, 3JH2-T(B)E, 3JH25A, and 3JH30A models. This manual is designed for both experienced mechanics and do-it-yourselfers, offering clear, step-by-step instructions and high-quality illustrations to guide you through every repair process. It covers all essential aspects of maintenance and repair, including: **Chapter 1: General** This chapter covers general information about the engine, including safety precautions, specifications, and basic operating procedures. **Chapter 2: Basic Engine Parts** This chapter provides detailed information about the engine's core components, such as the crankshaft, connecting rods, pistons, and cylinder heads. You'll find diagrams and descriptions of each part, helping you identify and understand their functions. **Chapter 3: Fuel Injection Equipment** Detailed explanations and visual aids guide you through the intricacies of the fuel injection system, including the injectors, pump, and control mechanisms. You'll learn how to diagnose and resolve common fuel-related issues. **Chapter 4: Intake and Exhaust System** This chapter focuses on the engine's intake and exhaust systems, covering components like the air intake manifold, exhaust manifold, and turbocharger (if equipped). The manual provides guidance on inspecting, cleaning, and maintaining these critical systems. **Chapter 5: Lubrication System** The lubrication system keeps your engine running smoothly. This chapter delves into the oil pump, filters, and oil passages, offering step-by-step instructions for maintaining and replacing these components. **Chapter 6: Cooling Water System** This chapter covers the engine's cooling water system, including the water pump, thermostat, and radiator. You'll find instructions for checking coolant levels, flushing the system, and repairing leaks. **Chapter 7: Reduction and Reversing Gear** This chapter focuses on the transmission system, providing detailed information on the reduction gear, reversing mechanism, and related components. You'll learn about adjustments, troubleshooting, and repairs specific to the transmission. **Chapter 8: Remote Control** This chapter covers the remote control system, including the throttle and shift levers, cables, and control box. Learn how to maintain, troubleshoot, and repair the remote control system for safe and reliable engine operation. **Chapter 9: Electrical System** This chapter tackles the engine's electrical system, covering components like the starter motor, alternator, wiring harness, and sensors. You'll find instructions on diagnosing electrical faults and carrying out repairs. **Chapter 10: Disassembly and Reassembly** This chapter provides comprehensive guidance on disassembling and reassembling various engine components. It covers procedures for removing and reinstalling parts, ensuring proper alignment and torque specifications.

## Yanmar Marine Diesel Engines: A Reliable Choice for Seafaring Adventures The Yanmar 3JH2-(B)E, 3JH2-T(B)E, 3JH25A, and 3JH30A marine diesel engines are renowned for their robust construction, reliable performance, and fuel efficiency, making them a popular choice for a wide range of boat applications. These four-cylinder, naturally aspirated engines are available in various power outputs, ranging from the 3JH2 series at 18.5 to 24.5 horsepower, to the larger 3JH30A boasting 30 horsepower, offering a suitable option for boats from small dinghies to larger sailboats. Yanmar's commitment to quality shines through in the meticulous engineering of these engines. The 3JH2 series features a compact design, making installation efficient even in tight spaces. Their innovative turbocharging technology in the 3JH2-T(B)E series increases performance and torque while maintaining fuel economy. The 3JH25A and 3JH30A models offer durable and reliable performance, providing substantial power for larger vessels. The engines incorporate Yanmar's signature robust construction, with features like a cast-iron cylinder block, direct-injection fuel system, and a durable crankshaft, ensuring longevity and minimizing maintenance needs. These robust engines are known for their smooth operation and quiet running, contributing to a more enjoyable boating experience.