Yanmar 1GM10, 2GM20, 3GM30, 3HM35 Marine Diesel Engines OEM Service & Repair Manual

Yanmar 1GM10, 2GM20, 3GM30, 3HM35 Marine Diesel Engines OEM Service & Repair Manual

Models covered:

• Yanmar 1GM10
• Yanmar 2GM20
• Yanmar 3GM30
• Yanmar 3HM35
• Yanmar 2GM20F
• Yanmar 3GM30F
• Yanmar 3HM35F
• Yanmar 1GM10C
• Yanmar 2GM20C
• Yanmar 3GM30C
• Yanmar 3HM35C

The Yanmar 1GM10, 2GM20, 3GM30, 3HM35 Marine Diesel Engines OEM Service & Repair Manual provides full factory procedures for maintaining and overhauling Yanmar’s GM and HM-series marine diesels. Whether you’re running a single-cylinder 1GM10 or a triple-cylinder 3GM30, this manual covers service data across fresh-water and sea-water cooled variants, including “C” and “F” models with updated configurations.

What's Inside the Yanmar 1GM10, 2GM20, 3GM30, 3HM35 Marine Diesel Engines OEM Service & Repair Manual

General Information

Covers all essential specs, engine construction details, and performance data for Yanmar 1GM10, 2GM20, 3GM30, and 3HM35 marine diesel engines. Includes full piping diagrams and layout references to help identify every system on board.

Basic Engine

Step-by-step instructions for servicing the engine block, cylinder head, pistons, crankshaft, and camshaft assemblies. Also includes timing gear procedures, flywheel inspection, and precise wear limits for reliable rebuilds.

Fuel System

Detailed guidance on the Yanmar diesel fuel injection system — from pump calibration and nozzle service to filter replacement and bleed procedures. Perfect for diagnosing poor fuel delivery or starting issues.

Governor

Explains governor function and adjustment to maintain consistent RPM under varying loads. Covers idling limiter setup, linkage inspection, and speed control calibration to ensure smooth, efficient operation.

Intake & Exhaust System

Includes inspection and servicing of the intake and exhaust manifolds, breather system, and connecting ducts. Procedures for removing carbon buildup and maintaining proper air and exhaust flow are clearly outlined.

Lubrication System

Comprehensive coverage of oil pump service, pressure regulator valve checks, and oil filter replacement. Also includes lubrication circuit flow diagrams and preventive maintenance for optimal engine protection.

Sea-Water & Fresh-Water Cooling Systems

Explains both seawater and freshwater cooling layouts, with repair steps for pumps, thermostats, and heat exchangers. Also covers zinc anode inspection and replacement to prevent internal corrosion and maintain proper temperature control.

Reduction & Reversing Gear

Maintenance and overhaul instructions for KM and KMV series transmissions. Covers shifting mechanism operation, gear inspection, reassembly procedures, and lubrication requirements for smooth, quiet performance.

Electrical System

Complete coverage of wiring diagrams, battery maintenance, and charging components including starter motor and alternator (12V/35A and 12V/55A models). Also includes tachometer calibration and instrument panel troubleshooting steps.

Remote Control System

Guidance for clutch and speed regulator linkage adjustment, engine stop system setup, and remote throttle calibration. Ensures responsive and safe operation from helm controls.

Operating Instructions

Includes recommended oils and fluids, correct startup and shutdown procedures, and practical troubleshooting guides. Helps operators identify and correct common running issues before they turn into major repairs.

Disassembly & Reassembly (Sea-Water & Fresh-Water Cooled Engines)

Complete teardown and rebuild procedures for both seawater- and freshwater-cooled variants. Includes torque specifications, sealant application points, and step-by-step reassembly sequences straight from Yanmar factory standards.

Built for Mechanics, Trusted by DIYers

This manual is the same reference used by certified marine techs — but written clearly enough that a competent DIYer can follow along. Whether you're chasing cooling issues, rebuilding the injection pump, or servicing the reduction gear, it’s all broken down into factory-backed steps with exact torque specs and test procedures.

Reliable Procedures for Dockside or Workshop Repairs

If you’re rebuilding in the off-season or troubleshooting in a tight marina berth, this manual keeps the workflow tight and efficient. It’s structured by system, so you’re not flipping through page after page to find a spec or step. Follow Yanmar’s diagnostic paths, service intervals, and reassembly instructions exactly as intended.

Fully Searchable PDF Format

The manual is delivered as a high-resolution PDF compatible with Windows, macOS, Android, iOS, and Linux. Whether you're working on a laptop in the cabin or referencing it on your phone from the engine bay, it's easy to access and print as needed.

Factory Coverage for GM and HM Series

The Yanmar 1GM10, 2GM20, 3GM30, 3HM35 OEM Service & Repair Manual is your definitive reference for servicing Yanmar’s most widely used small marine diesels. No shortcuts — just factory-correct guidance from top to bottom.

Language: English
Compatibility: Windows, macOS, Linux, iOS, Android
Requirements: PDF Reader (e.g., Adobe Reader)