Part of the Yanmar Repair Manuals.
Before you cast off, make sure you have this 263-page Yanmar 1GM10 operation manual PDF (OEM #49961 - 202281) covering the entire GM series diesel engine family, including the 2GM20, 3GM30, and all F/V variants. Inside, you get complete A-Type and B-Type instrument panel wiring diagrams, detailed piping layouts, and a full troubleshooting section for hard starts and compression issues. Open to the maintenance chapters for exact procedures on fuel bleeding, cooling water system care, and drive belt adjustments. Verify your fuel injection pressure is hitting 170 ± 5 kg/cm² and ensure your control cables maintain a minimum bend radius of 200 mm to prevent binding. A dead motor at sea is not an option. Bookmarked for fast navigation, you can pull this digital file up on your tablet in the engine room and get straight to work.
What's Inside This Yanmar GM Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Safety & Precautions | 5-7 | Name of Parts, Fire Prevention, Exhaust Gas Prevention, Burn Prevention, General Safety Tips, Battery Charging Safety |
| Machine Identification | 9-10 | Air Intake Side Parts, Exhaust Side Parts, Cylinder Number Identification |
| Specifications | 11-14 | Direct Sea Water Cooling Type Gm Series, Direct Sea Water Cooling Type Gmf Series, Direct Sea Water Cooling Type GMV-series, Fresh Water Cooling Type GMFV-series |
| Engine Handling Fundamentals | 15-16 | Running-In Operation, Fuel Management, Lubrication Management, Cooling System Care, Drive Belt Adjustment, Starting Procedures |
| Installation | 17-22 | Engine Mounting, Engine Centering, Exhaust System, Sea Water Cooling System, Fuel System, Electric System |
| Fuel, Lube Oil & Cooling Water | 23-25 | Fuel Oil Selection and Handling, Lube Oil Selection and Supply, Cooling Water Handling, Cooling Water Supply and Check, Cooling Water Refilling |
| Break-In & Operation | 26-32 | Fuel Oil Supply and Draining, Lube Oil Supply, Air Bleeding, Engine Parts Lubrication, Safety Checks, Pilot Lamp Check, Starting, Cautions After Engine Starting, During Engine Operation, Engine Stopping, Draining the Cooling Water |
| Maintenance & Storage | 33-40 | Fuel Oil System, Lube Oil System, Cooling Water System, Battery Maintenance, V-Belt Tension Adjustment, Engine Body Checks, Engine Cleaning, Lube Oil Change, Engine Coating/Covering, Battery Removal/Charging |
| Troubleshooting | 41-42 | - |
| Francais | 43-82 | - |
| Deutsch | 83-121 | - |
| Espanol | 122-160 | - |
| Italiano | 161-199 | - |
| Svensk | 200-237 | - |
| Appendix: Component Diagrams | 238-262 | Piping Diagrams, Wiring Diagrams, Fuel Oil System Components, Lubricating Oil System Components, Cooling Water System Components, Electrical System Components |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Starter motor power | DC 12V, 1.0kW | p. 11 |
| Minimum radius of cable bend | 200 mm (7.9 in.) | p. 24 |
| Fuel injection pressure | 170 ± 5 kg/cm² (2347 - 2489 lb/in.²) | p. 11 |
| Bore x Stroke | 75 x 72 mm (2.95 x 2.83 in) | p. 11 |
| Compression Ratio | 23.0 | p. 11 |
| Replace Fuel Filter Interval | Every 300 hrs | p. 34 |
| Replace Lube Oil Filter Interval | 1st time after 50 hrs, 2nd time and thereafter every 300 hrs | p. 35 |
| Adjust Valve Clearance Interval | Every 600 hrs | p. 38 |
| Cooling Water Pump Belt Tension (Fresh water) | 10 mm (with 10 kg thumb force) | p. 36 |
| Cooling Water Pump Belt Tension (Sea water) | 5-7 mm (with 10 kg thumb force) | p. 36 |
| 1GM10, 2GM20, 1GM10V, 2GM20V, 2GM20F, 2GM20FV | ||
| Fuel Injection Timing (1- and 2-cylinder models) | 15° ± 1° b.T.D.C. | p. 11 |
| 3GM30, 3GM30F, 3GM30V, 3GM30FV | ||
| Fuel Injection Timing (3-cylinder models) | 18° ± 1° b.T.D.C. | p. 11 |
Yanmar GM Series Common Problems This Manual Covers
Yanmar 3GM30 slow cranking speed or intermittent no-start condition when turning the key
Check the starting-aid circuit and battery cables. Inspect terminals for corrosion and measure the starter motor output to confirm it draws DC 12V, 1.0kW. Verify the minimum radius of the cable bend is at least 200 mm (7.9 in.) as shown on page 24.
Manual Section: Engine Starting Difficulties p. 41Engine cranks fast but refuses to fire even with fresh fuel and repeated priming attempts
Bleed the fuel system to remove trapped air. Remove and replace the main fuel filter, which must be done every 300 hrs according to the maintenance schedule on page 34. Test the fuel injection pressure to ensure it hits exactly 170 ± 5 kg/cm² (2347-2489 lb/in.²).
Manual Section: 8. Periodic Checks and Maintenance p. 34Persistent overheating alarms or rapid coolant temperature spikes when operating under heavy load
Inspect the raw-water impeller for missing vanes and check the cooling water pump belt tension. Adjust the fresh water pump driving belt to 10 mm deflection with 10 kg thumb force, referencing the procedures on page 36. Drain and flush the cooling circuit.
Manual Section: 8. Periodic Checks and Maintenance p. 36Excessive diesel knock, rough idling, and noticeable loss of compression during cold starts
Adjust the intake and exhaust valve clearance, which is required every 600 hrs as specified on page 38. Inspect the fuel injector nozzles for fouling and verify the injection timing. Check engine mounts for delamination if severe vibration persists after tuning.
Manual Section: 8. Periodic Checks and Maintenance p. 38Frequently Asked Questions
How do I bleed air after changing the fuel filter?
To bleed air after changing the fuel filter, first loosen the air bleeding screws on the fuel filter and fuel injection pump. Then, vent air from the fuel injection piping by loosening the fuel injection pipe nipple on the fuel injection valve side, repeating this several times. After venting, tighten the nipple firmly. p. 19
What
The alarm buzzer will sound when the engine is stopped with the starter switch "ON". This indicates low lube oil pressure, which is considered normal in this specific scenario and does not signify engine trouble. p. 24
How quickly can I access this Yanmar 1GM10, 2GM20, 3GM30, 2GM20F, 3GM30F?
Immediate download of the complete 263-page searchable Operation Manual (13 MB). Access it on any device, from a laptop at your desk to a phone in the field.
Can I print specific sections of this Yanmar 1GM10, 2GM20, 3GM30, 2GM20F?
Yes, print as many copies as you want, and there are no restrictions. Many mechanics print the section they need and bring it to the shop floor.
Can I find wiring schematics in this Yanmar 1GM10, 2GM20, 3GM30, 2GM20F?
Yes, this Yanmar 1GM10, 2GM20, 3GM30, 2GM20F, 3GM30F, 1GM10V, 2GM20V, 3GM30V, 2GM20FV, 3GM30FV, GM series Operation Manual includes a wiring diagram for the electrical system.
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