Part of the Yanmar Repair Manuals.
From the cylinder head torque sequence to the trochoid oil pump, this 280-page Yanmar factory service manual takes the 3TNM68 and 3TNM72 industrial diesels apart system by system: engine internals, fuel system, cooling, lubrication, starter motor, alternator, wiring, and a dedicated troubleshooting chapter.
Every rebuild stalls at the same place, and it is never the wrenching. It is the one number you do not have: a bearing clearance, a valve gap, an injection pressure, a bolt torque. The Engine chapter carries cylinder head, camshaft, timing gear train, crankshaft and piston specifications, so the measuring happens at the bench instead of in a forum thread.
Delivered as a PDF (17.69 MB, English, 2008, publication 0BTNM-G00100) with 336 bookmarks for jumping straight to a section. Download it after checkout and print only the pages that go to the bench.
What's Inside This Yanmar 3TNM68, 3TNM72 Manual
| System | Pages | Key Topics |
|---|---|---|
| Yanmar Warranties | 9-16 | Yanmar Limited Warranty, Emission System Warranty, Yanmar Co., Ltd. Limited Emission Control System Warranty - Usa Only |
| Safety | 17-36 | - |
| General Service Information | 37-64 | Component Identification, Location of Labels, EPA / Carb Emission Control Regulations - Usa Only, Emission Control Labels, The 97/68/EC Directive Certified Engines, Engine Family |
| Periodic Maintenance | 65-102 | Introduction, Precautions, Periodic Maintenance Schedule, Periodic Maintenance Procedures |
| Engine | 103-162 | Before You Begin Servicing, Introduction, Cylinder Head Specifications, Camshaft and Timing Gear Train Specifications, Crankshaft and Pistons Specifications |
| Fuel System | 163-190 | Before You Begin Servicing, Introduction, Fuel System Specifications, Special Service Tools, Measuring Instruments, Fuel System Diagram, Fuel System Components |
| Cooling System | 191-200 | Before You Begin Servicing, Introduction, Cooling System Diagram, Engine Coolant Pump Components, Engine Coolant System Check, Engine Coolant Pump |
| Lubrication System | 201-210 | Before You Begin Servicing, Introduction, Oil Pump Service Information, Lubrication System Diagram, Trochoid Oil Pump |
| Starter Motor | 211-230 | Before You Begin Servicing, Introduction, Starter Motor Information, Starter Motor Specifications, Starter Motor Troubleshooting, Starter Motor Components |
| Alternator | 231-252 | Before You Begin Servicing, Introduction, Standard and Optional Dynamo Information, Standard and Optional Alternator Information, Alternator Specifications, Dynamo Specifications |
| Electric Wiring | 253-260 | Electric Wiring Precautions, Electric Wire Resistance, Battery Cable Resistance, Electrical Wire Sizes - Voltage Drop, Conversion of Awg to European Standards |
| Troubleshooting | 261-279 | Special Service Tools, Troubleshooting by Measuring Compression Pressure, Quick Reference Table for Troubleshooting |
Yanmar 3TNM68, 3TNM72 Common Problems This Manual Covers
Hard starting or dies after firing
Air pulled into the fuel system or a restricted filter will make either engine crank clean and refuse to run. The Fuel System chapter includes the system diagram, component breakdown and specifications you need to trace the restriction and bleed the circuit properly.
Manual Section: Fuel System p. 163Low power and smoke under load
When output drops and the exhaust darkens under load, the cause could be fueling, air, or worn rings, and guessing is expensive. The Troubleshooting chapter routes the symptom through compression pressure measurement and a quick reference table so you condemn the right parts.
Manual Section: Troubleshooting p. 261Overheating and coolant loss
A stuck thermostat or tired coolant pump will cook a small diesel quickly. The Cooling System chapter has the system diagram, coolant pump component breakdown, and the coolant system check procedure to isolate the failure before it becomes a head job.
Manual Section: Cooling System p. 191Low oil pressure or bearing knock
Low oil pressure on these engines is a stop-now condition, not something to monitor. The Lubrication System chapter covers the trochoid oil pump service procedure and lubrication system diagram so you can verify the pump before pulling the crank.
Manual Section: Lubrication System p. 201Blow-by and rising oil consumption
Oil mist from the breather and a climbing consumption rate point at ring end gap, cylinder wear or stuck rings. The Engine chapter carries crankshaft and piston specifications so you can measure the bore and rings against limits instead of eyeballing them.
Manual Section: Engine p. 103Slow or intermittent cranking
Slow cranking gets blamed on the battery long after the starter is the real problem. The Starter Motor chapter includes specifications, a component breakdown and its own troubleshooting procedure to separate a weak battery and bad grounds from a worn motor.
Manual Section: Starter Motor p. 211Battery not charging
These engines came with standard and optional charging setups, and testing the wrong one wastes an afternoon. The Alternator chapter covers both dynamo and alternator information with specifications, so you identify what is fitted and order the correct replacement the first time.
Manual Section: Alternator p. 231Frequently Asked Questions
Which engines does this manual cover?
The Yanmar 3TNM68 and 3TNM72 industrial diesel engines. It is the 2008 factory service manual, Yanmar publication number 0BTNM-G00100, written in English across 280 pages. It covers the engine itself regardless of what equipment it is installed in.
Does it include valve lash and rebuild specifications?
Yes. The Engine section covers cylinder head, camshaft and timing gear train, and crankshaft and piston specifications, and the General Service Information chapter carries the quick-reference service data, including valve gap, injection pressure and compression figures for both engines. p. 103
Can it help diagnose low power or hard starting?
Yes. The Troubleshooting section includes a quick reference table for troubleshooting, the special service tools list, and a procedure for troubleshooting by measuring compression pressure, which is the fastest way to separate fuel problems from worn internals. p. 261
Are wiring details included?
Yes. The Electric Wiring section covers wiring precautions, electric wire and battery cable resistance, wire sizes and voltage drop, and conversion of AWG to European standards. Starter motor and alternator electrics are handled in their own dedicated chapters. p. 253
How is this Yanmar 3TNM68 Service Manual delivered?
Immediate download of the complete 280-page searchable Service Manual (18 MB). Access it on any device, from a laptop at your desk to a phone in the field.
Is this Yanmar 3TNM68 Service Manual printable?
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 3TNM68 manual have electrical schematics?
Complete wiring diagrams are included, covering all electrical circuits, harness routing, and connector pinouts for the Yanmar 3TNM68, 3TNM72.
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