Rebuilding your marine diesel engine starts with this 474-page Yanmar 1GM10(C), 2GM20(F)(C), GM- series service manual PDF (OEM #0000 A0A1361), covering the complete teardown and assembly for the 3GM30(F)(C) and 3HM35(F)(C) variants. Inside, you get complete piping diagrams for the cooling systems, full wiring schematics for the instrument panel, and step-by-step disassembly procedures for both direct sea-water and fresh-water setups. Open to the troubleshooting section to diagnose fuel injection faults, then use the detailed tightening torque tables to put it all back together. Verify your high idling speed is dialed into 3825 ± 25 min⁻¹, and confirm the fuel injection pressure hits exactly 170 kgf/cm² before dropping the engine back in the hull. A dead engine on the water ruins the weekend. Download this bookmarked file directly to your tablet, click straight to the spec you need, and get your boat running right.
What's Inside This Yanmar GM/HM Series Manual
| System | Pages | Key Topics |
|---|---|---|
| History of Revision | 3 | ARB(EPA) Certified Tamper Resistance, EPA/ARB Certified Engine Identification, Safe Servicing Information, Engine Specifications, Manual Content Updates |
| A. Engine Model Name | 9 | 2-Cylinder, Marine Engine Series, Discrimination of Engine Type, Discrimination of Old GM(F) Model |
| B. Engine Model Name Plate and Clutch Model Name Plate | 10-11 | Item Descriptions on Model Name Plates, Information to Be Forwarded to Us, Engine Model Name Plate Location, Clutch Model Name Plate Location |
| Cylinder Number | 12 | Cylinder Numbering Sequence, Flywheel Side, Devices and Parts Connected with Cylinder Head, Fuel Injection Pump Numbering |
| Chapter 0 for Safety | 13-18 | 1. for Safe Servicing, 2. Precaution for Safe Servicing |
| Chapter 1 General | 19-47 | 1. Specifications, 2. Principal Construction, 3. Performance Curves, 4. Features, 5. Engine Cross-Sections, 6. Dimensions, 7. Piping Diagrams |
| Chapter 2 Basic Engine | 48-111 | 1. Cylinder Block, 2. Cylinder Head, 3. Piston, 4. Connecting Rod, 5. Crankshaft, 6. Flywheel and Housing, 7. Camshaft, 8. Timing Gear |
| Chapter 3 Fuel System | 112-146 | 1. Fuel Injection System, 2. Injection Pump, 3. Injection Nozzle, 4. Fuel Filter, 5. Fuel Feed Pump, 6. Fuel Tank(Option) |
| Chapter 4 Governor | 147-160 | 1. Governor, 2. Injection Limiter, 3. No-Load Maximum Speed Limiter, 4. Idling Adjuster, 5. Engine Stop Lever |
| Chapter 5 Intake and Exhaust System | 161-168 | 1. Intake and Exhaust System, 2. Intake Silencer, 3. Exhaust System, 4. Breather |
| Chapter 6 Lubrication System | 169-183 | 1. Lubrication System, 2. Oil Pump, 3. Oil Filter, 4. Oil Pressure Regulator Valve, 5. Oil Pressure Measurement |
| Chapter 7 Direct Sea-Water Cooling System | 184-201 | 1. Cooling System, 2. Water Pump, 3. Thermostat, 4. Anticorrosion Zink, 5. Kingston Cock(Optional), 6. Bilge Pump and Bilge Strainer(Optional) |
| Chapter 8 Fresh Water Cooling System | 202-220 | 1. Cooling System, 2. Sea Water Pump, 3. Fresh Water Pump, 4. Heat Exchanger, 5. Filler Cap and Subtank, 6. Thermostat, 7. Cooling Water Temperature Switch, 8. Precautions |
| Chapter 9 Modifying the Cooling System | 221-233 | 1. General, 2. Disassembly of Sea Water-Cooled Engine, 3. Assembling Modified Parts to the Fresh Water -Cooled Engine, 4. Cautions When the Engine Is Installed Inboard |
| Chapter 10 Reduction and Reversing Gear | 234-333 | [A] for Engine Models 1GM10.2GM20 and 3GM30 (Construction, Shifting Device, Servicing, Disassembly, Reassembly) |
| Chapter 11 Remote Control System | 334-341 | 1. Construction, 2. Clutch and Speed Regulator Remote Control, 3. Engine Stop Remote |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| 1GM10(C), 2GM20(F)(C), 3GM30(F)(C) | ||
| Idling Speed (High) | 3825 ± 25 min⁻¹ | p. 20 |
| Compression Ratio | 23.0 | p. 20 |
| 3HM35(F)(C) | ||
| Idling Speed (High) | 3600 ± 25 min⁻¹ | p. 20 |
| Compression Ratio | 24.8 | p. 20 |
| 1GM10(C) | ||
| Fuel Injection Pressure | 170 kgf/cm² (2418 lb/in.²) | p. 114 |
| 2GM20(F)(C), 3GM30(F)(C), 3HM35(F)(C) | ||
| Fuel Injection Pressure | 160 kgf/cm² (2276 lb/in.²) | p. 114 |
Yanmar GM/HM Series Common Problems This Manual Covers
Yanmar 3GM30 engine cranks but will not start or requires repeated key switch attempts p. 359
Inspect the starter motor and control circuit wiring for corrosion. Measure the starter motor S114-303 standard spring load, verifying it meets 1.6 kg (3.527 lb) as shown on page 359. Replace any undersized harness cables to eliminate voltage drop and ensure the solenoid receives full current.
Manual Section: Starter Motor TroubleshootingExcessive white smoke and rough running with failure to develop power under heavy load p. 72
Test the fuel injection system and verify the nozzle spray pattern. Adjust the intake and exhaust valve head clearance to exactly 0.2mm (0.0079in.) as detailed on page 72. Bleed all air from the fuel lines, inspect the injectors for wear, and correct the injection timing.
Manual Section: Fuel System Inspection & TroubleshootingLow oil pressure warning alarm activates or engine develops a rapid internal knocking noise p. 173
Check the oil dipstick level immediately. Fill the engine oil to the correct total effective capacity, which is 1.3 L for the 1-cylinder model as noted on page 173. Inspect the oil pressure switch and verify the internal pump bearings are not completely worn.
Manual Section: Chapter 6 Lubrication SystemIntermittent no-crank conditions or severe loss of compression during cold weather operation p. 469
Remove the cylinder head and inspect the gasket sealing surface for severe warping. Torque the cylinder head bolts to 7.5 kgf·m (54.2 ft·lb) during reassembly of the 1-cylinder model according to page 469. Verify the compression ratio reaches 23.0 before returning the unit to service.
Manual Section: Chapter 15 Disassembly and Reassembly (Fsesh Water Cooling Engine)Frequently Asked Questions
How to reset the Yanmar 1GM10 service alarm?
The manual does not describe a specific "service alarm reset" procedure for the Yanmar 1GM10. Alarms, such as the water temperature warning lamp or oil pressure warning lamp, indicate issues that require troubleshooting and repair of the underlying problem, as stated on page 398: "If the lamp or buzzer stay on, immediately stop the engine and check for trouble."
How to reset the Yanmar 2GM20 fuel filter warning?
The manual does not describe a specific "fuel filter warning" light on the instrument panel or a procedure to "reset" such a warning for the Yanmar 2GM20. Instead, it outlines maintenance for the fuel filter, recommending inspection and cleaning, and replacement of the element every 250 hours or when it is dirty or damaged, as detailed on page 141.
How to reset the Yanmar 3GM30 panel after an overheat alarm?
The manual indicates that an overheat alarm, signaled by the water temperature warning lamp and alarm buzzer on the instrument panel, requires stopping the engine and troubleshooting the cause. There is no specific "reset" procedure for the panel after an overheat alarm; the alarm is expected to clear once the underlying issue, such as insufficient cooling water or a faulty thermostat, is resolved, as described on page 398.
How to reset the Yanmar 3HM35 low oil pressure alarm?
The manual indicates that a low oil pressure alarm, shown by the oil pressure warning lamp and alarm buzzer, requires stopping the engine and troubleshooting the cause. There is no specific "reset" procedure for the panel; the alarm is expected to clear once the underlying issue is resolved. The standard secondary oil pressure for the 3HM35(F)(C) is 0.5 kgf/cm² (7.11 lb/in.²) at 850 rpm, as specified on page 183.
How quickly can I access this manual after buying?
Instant PDF download. You get the full 474-page searchable Service Manual immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Is this Yanmar 1GM10(C) & variants Service Manual printable?
Yes. The PDF has no DRM restrictions, so print any page or section you need for your shop. Works with any standard printer.
Does this Service Manual have electrical diagrams?
Yes, this Yanmar 1GM10(C) & variants Service Manual includes complete electrical wiring diagrams, wire routing, and connector pinouts.
Document Quality
This document is a scanned PDF, but it includes an OCR layer, so you can search and copy the full text. The text is generally crisp and readable, though some characters have minor scanning artifacts. Diagrams and illustrations are raster images, showing some pixelation, but their labels remain clear. Pages are clean with no significant stains, marks, or skewed content. You will find several blank pages throughout the document, typically at chapter ends.
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