Part of the Yanmar Repair Manuals.
Before you loosen a single injection line, look at the publication code: 0BYMM-G00100 is Yanmar's own factory number for this service manual, and the 248 pages behind it cover the 3YM30, 3YM20 and 2YM15 marine diesels, including the C-spec 3YM30C, 3YM20C and 2YM15C, from 2005 to 2008.
Guessing on these engines has a price: a second teardown because a rod bolt went in at the wrong torque, or an injector replaced when the real fault was air in the fuel. This manual gives you the measured answer instead, covering valve lash, injection pump and governor service, seawater pump and heat exchanger work, full disassembly and reassembly, and symptom-based troubleshooting charts.
The PDF is bookmarked throughout, so the service standards and bolt torque tables you need before the head goes back on are a click away, and every page prints clean.
What's Inside This Yanmar 2YM15 / 3YM20 / 3YM30 Manual
| System | Pages | Key Topics |
|---|---|---|
| History of Revision | 3-4 | Specifications Table, Engine Outline, Piping Diagram, Seawater Pump Rotating Direction, Engine Mounting Bolt Side Pitch, No-Load Max. Speed |
| For Safety | 13-18 | Safety Labels, Service Area, Work Wear, Tools, Fastener Torque, Electrical Precautions |
| General | 19-49 | Exterior Views, Specifications, Fuel Oil, Lubricating Oil and Cooling Water, Engine Outline, Piping Diagrams |
| Inspection and Adjustment | 50-83 | Periodic Maintenance Schedule |
| Troubleshooting | 84-98 | Preparation Before Troubleshooting, Quick Reference Chart for Troubleshooting, Troubleshooting (Concerning Engine and Fuel Injection Equipment) |
| Disassembly and Reassembly | 99-138 | Disassembly and Reassembly Precautions, Disassembly and Reassembly Tools |
| Inspection and Servicing of Basic Engine Parts | 139-168 | Cylinder Block (Parts, Cleaning of Oil Holes, Color Check Procedure, Cap Plugs, Cylinder Bore Measurement) |
| Fuel Injection Equipment | 169-185 | Fuel Injection Pump/Governor, Fuel Feed Pump, Fuel Filter, Fuel Tank |
| Intake and Exhaust System | 186-188 | Intake Silencer, Intake Manifold, Rocker Arm Cover, Exhaust Manifold, Mixing Elbow, Breather System, Diaphragm Assy, Exhaust System |
| Lubrication System | 189-193 | Lube Oil Pump, Lube Oil Filter, Rotary Waste Oil Pump (Optional) |
| Cooling Water System | 194-212 | Seawater Pump, Fresh Water Pump, Heat Exchanger, Pressure Cap and Coolant Recovery Tank, Thermostat |
| Reduction and Reversing Gear | 213 | Marine Gear, Clutch, Propeller Shaft, Remote Control, Shift Lever |
| Remote Control (Optional) | 214-219 | Remote Control System, Remote Control Installation, Remote Control Inspection, Remote Control Adjustment |
| Electrical System | 220-238 | Battery, Starting Motor, Alternator Standard, 12V/60A, Alternator 12V/80A (Optional), Instrument Panel, Warning Devices |
| Service Standards | 239-245 | Engine Tuning, Engine Body, Lubricating Oil System (Trochoid Pump) |
| Tightening Torque for Bolts and Nuts | 246 | Main Bolt and Nut, Standard Bolts and Nuts (Without Lube Oil) |
| Colophon | 247 | - |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Head bolt tightening torque | 53.9-57.9 N•m (5.5-5.9 kgf•m) | p. 246 |
| Rod bolt tightening torque | 22.6-27.5 N•m (2.3-2.8 kgf•m) | p. 246 |
| Fuel injection pipe joint nut tightening torque | 29.4-34.4 N•m (3.0-3.5 kgf•m) | p. 246 |
| Fuel filter replacement interval | 250 hours or whenever dirty/damaged | p. 184 |
| Fuel filter tightening torque | 20-24 N•m | p. 66 |
| Lube oil filter replacement interval | Initial 50 hours or one month operation | p. 55 |
| Lube oil filter tightening torque | 20-24 N•m (177-212 lb-in) | p. 56 |
| Seawater pump impeller replacement interval | Every 1000 hours or four years | p. 67 |
| Seawater pump cooling water leakage | less than 3 cm³/h | p. 197 |
| Thermostat valve opening temperature | 69.5-72.5°C | p. 80 |
| Thermostat full open temperature | 85°C | p. 76 |
| Fuel injection opening pressure | 12.3-13.28 MPa (125-135 kgf/cm²) | p. 73 |
Yanmar 2YM15 / 3YM20 / 3YM30 Common Problems This Manual Covers
Cranks but will not start
Air pulled in through a loose fitting or a clogged filter is the classic cause after a filter change or a long layup. This chapter walks through the injection pump and governor, feed pump, fuel filter and tank so you can chase the restriction to its source instead of swapping parts.
Manual Section: 6. Fuel Injection Equipment p. 169Overheating under load
A worn seawater pump impeller or a fouled heat exchanger lets the engine run cool at idle and hot the moment you load it. The cooling chapter covers seawater pump teardown, fresh water pump, heat exchanger service and thermostat testing, with the impeller on a 1000 hour or four year replacement interval.
Manual Section: 9. Cooling Water System p. 194Low oil pressure warning
A pressure alarm points to a tired trochoid pump, a blocked filter or bearing clearance gone wide, and none of those forgive being ignored. This chapter covers the lube oil pump, oil filter and the optional rotary waste oil pump so you can rule each one out in order.
Manual Section: 8. Lubrication System p. 189White smoke and rough running
Misfire, smoke and uneven power usually trace back to air in the fuel, injector wear or lost compression. The quick reference chart works from the symptom toward the cause, including troubleshooting by measuring compression pressure.
Manual Section: 3. Troubleshooting p. 84Valve lash out of specification
Lash that closes up costs compression and makes hot restarts hard, especially on the two-cylinder 2YM15. The periodic maintenance schedule pins down when to check it, and the spec is 0.15-0.25 mm for intake and exhaust across all three engines.
Manual Section: 2. Inspection and Adjustment p. 50Starter clicks, engine will not crank
Marine wiring corrodes, batteries fade over a winter layup, and the starting motor takes the blame. The electrical chapter covers the battery, starting motor, the standard 60A and optional 80A alternators, instrument panel and warning devices.
Manual Section: 12. Electrical System p. 220Bore and bearing wear at rebuild
Once the engine is apart on the stand, guessing at cylinder condition means doing the job twice. This chapter gives the cylinder bore measurement procedure, color check method for cracks, and cleaning of oil holes before anything goes back together.
Manual Section: 5. Inspection and Servicing of Basic Engine Parts p. 139Frequently Asked Questions
Which Yanmar engines does this service manual cover?
It covers the Yanmar 3YM30, 3YM20 and 2YM15 marine diesels and their C-spec versions, the 3YM30C, 3YM20C and 2YM15C, built 2005 to 2008. It is Yanmar publication 0BYMM-G00100, 248 pages, in English.
Are cylinder head and rod bolt torque values included?
Yes. Section 14, Tightening Torque for Bolts and Nuts, lists rod bolts at 22.6-27.5 Nm and fuel injection pipe joint nuts at 29.4-34.4 Nm, plus standard values for unlisted fasteners. Cylinder head bolts are a TWO-STEP tightening, not a single figure: 24-32 Nm on the first step, then 53.9-57.9 Nm final. p. 246
Does it give valve clearance and injection pressure specs?
The manual lists valve clearance at 0.15-0.25 mm for intake and exhaust and fuel injection opening pressure at 12.3-13.28 MPa, and the Troubleshooting section covers measuring compression pressure. p. 239
Can I service the seawater pump and impeller with this manual?
Yes. The Cooling Water System chapter covers the seawater pump, fresh water pump, heat exchanger, pressure cap, recovery tank and thermostat. The impeller replacement interval is every 1000 hours or four years. p. 194
What format is this manual in?
This is a 248-page searchable PDF ready for immediate download. Works on any device, so pull it up on your phone while you're under the hood. No shipping, no waiting.
Am I able to print pages from this manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Does this Yanmar 3YM30 & variants manual include wiring diagrams?
Yes, full electrical schematics are included with wire colors, connector locations, and circuit descriptions.
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