Part of the Yanmar Repair Manuals.
The three-stage cylinder head torque sequence on a 6LY3 changes depending on whether the bolts are new or reused, and a guessed figure is how a head gasket fails twice. This 366-page Yanmar service manual, publication 0BLY3-G00100, is where the real numbers live for the 6LY3-ETP, 6LY3-STP and 6LY3-UTP marine diesels.
It follows the engine from periodic inspection through full teardown: disassembly and reassembly procedures, wear limits for the cylinder block, head, pistons, crankshaft and valve guides, fuel injection pump and nozzle service, turbocharger checks, and the cooling, lubrication and electrical systems. A symptom-based troubleshooting chapter includes the diagnostic trouble code list for the electronic control system.
The PDF is bookmarked and searchable, and it prints cleanly, so the torque tables and clearance charts can go to the bench and get dirty while the master copy stays clean on your laptop.
What's Inside This Yanmar 6LY3-ETP, 6LY3-STP, 6LY3-UTP Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 21-35 | Exterior Views, Main Specifications, Fuel Oil, Lubricating Oil and Cooling Water, Engine Outline, Piping Diagrams |
| Inspection and Adjustment | 36-75 | Periodic Maintenance Schedule |
| Troubleshooting | 76-148 | Preparation Before Troubleshooting, Trouble Code |
| Disassembly and Reassembly | 149-186 | Disassembly and Reassembly Precautions, Disassembly and Reassembly Tools |
| Inspection and Servicing of Basic Engine Parts | 187-227 | Cylinder Block, Cylinder Head, Piston and Piston Pins, Connecting Rod, Crankshaft and Main Bearing, Camshaft and Tappets, Timing Gear |
| Fuel Injection Equipment | 228-265 | Fuel Injection Pump / Governor / Timer, Fuel Injection Nozzle, Fuel Feed Pump, Fuel Filter, Electronic Control System |
| Intake and Exhaust System | 266 | Intake System, Exhaust System |
| Lubrication System | 267-275 | Lube Oil Pump, Lube Oil Filter, Lube Oil Cooler, Rotary Waste Oil Pump (Optional) |
| Cooling Water System | 276-300 | Seawater Pump, Fresh Water Pump, Heat Exchanger, Pressure Cap and Coolant Recovery Tank, Thermostat, Seacock (Optional) |
| Turbocharger | 301-323 | Construction and Function, Standards for Maintenance and Check, Periodical Checking Procedure, Disassembly Procedure, Cleaning and Checking Procedure |
| Reduction and Reversing Gear | 324 | - |
| Remote Control | 325-330 | Electronic Control System (Ecs) |
| Electrical System | 331-357 | Battery, Starting Motor, Alternator Standard, 12V/80A, Warning Devices, Air Heater, Fuse |
| Service Standards | 358-363 | Engine Tuning, Engine Body |
| Tightening Torque for Bolts and Nuts | 364-366 | Main Bolt and Nut, Standard Bolts and Nuts (Without Lube Oil) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Cylinder head bolt tightening torque (New bolt) | 1st: 118 N•m (12.0 kgf•m), 2nd: 177 N•m (18.0 kgf•m), 3rd: 216-236 N•m (22.0-24.1 kgf•m) | p. 364 |
| Cylinder head bolt tightening torque (Used bolt) | 1st: 108 N•m (11.0 kgf•m), 2nd: 167 N•m (17.0 kgf•m), 3rd: 196-216 N•m (20.0-22.0 kgf•m) | p. 364 |
| Fuel nozzle sleeve tightening torque | 52.9-62.7 N•m (5.4-6.4 kgf•m) | p. 364 |
| Nozzle fastening bolt tightening torque | 29.4-33.4 N•m (3.0-3.4 kgf•m) | p. 364 |
| Intake valve guide inside diameter (Standard) | 8.010-8.025 mm | p. 359 |
| Intake valve guide inside diameter (Limit) | 8.1 mm | p. 359 |
| Nozzle opening pressure (No.1 press.) | 24.00-24.98 MPa (245-255 kgf/cm2) | p. 250 |
| Nozzle opening pressure (No.2 press.) | 36.96-38.34 MPa (377-391 kgf/cm2) | p. 250 |
| General replacement instruction for gaskets and O-rings | Replace all gaskets and O-rings. | p. 149 |
| Lube oil filter (full flow) rubber packing tightening | After touching rubber packing, turn additional 3/4 of a turn. | p. 364 |
| Engine Displacement | 5.813 l | p. 22 |
| Low Idling Speed | 700±25 min-1 | p. 22 |
Yanmar 6LY3-ETP, 6LY3-STP, 6LY3-UTP Common Problems This Manual Covers
Electronic control faults and lost gauges
Owners of these electronically governed engines report throttle response and instruments dropping out from control system or wiring faults. The Troubleshooting chapter works from the symptom to the cause and includes the full diagnostic trouble code list, sensor diagnosis, and ECU connector pin configuration.
Manual Section: 3. Troubleshooting p. 76Hard starting and uneven running
Injector nozzles drift off their opening pressure and the engine starts to smoke, hunt, or run rough under load. The Fuel Injection Equipment section covers the injection pump, governor and timer, nozzle inspection and pressure setting, the feed pump, the filter, and the electronic control side.
Manual Section: 6. Fuel Injection Equipment p. 228Worn valve guides and low compression
Valve guide wear is a known sore point in this engine family, and a broken guide can take the bottom end with it. This section gives inspection procedures and wear limits for the cylinder head, valves and guides, plus pistons, rings, connecting rods, crankshaft and bearings, so you measure instead of guessing.
Manual Section: 5. Inspection and Servicing of Basic Engine Parts p. 187Overheating from a neglected raw water side
A tired seawater pump impeller or a scaled heat exchanger will push coolant temperature up long before an alarm sounds. The Cooling Water System section covers the seawater pump, fresh water pump, heat exchanger, pressure cap, thermostat, and the optional seacock.
Manual Section: 9. Cooling Water System p. 276Turbocharger fouling and boost loss
Carbon and salt-air fouling steal boost gradually until the engine will not reach rated speed. The Turbocharger chapter explains construction and function, maintenance standards, periodic checking, and full disassembly and cleaning procedures.
Manual Section: 10. Turbocharger p. 301Low or falling lube oil pressure
Falling oil pressure on a hot engine points at the pump, filter, or oil cooler, and each has its own checks. The Lubrication System section covers the circuit layout, lube oil pump, filter, oil cooler, and the optional rotary waste oil pump.
Manual Section: 8. Lubrication System p. 267Starting motor and charging system trouble
Slow cranking and dead panels usually trace to the battery, starting motor, or the 12V/80A alternator. The Electrical System section covers all three along with the warning devices, air heater, and fuses.
Manual Section: 13. Electrical System p. 331Frequently Asked Questions
Which engines does this manual cover?
It is the Yanmar service manual for the 6LY3-ETP, 6LY3-STP and 6LY3-UTP marine diesel engines, publication number 0BLY3-G00100 (2006), 366 pages, in English. All three variants are covered in the one document.
Does it include the cylinder head torque sequence and other torque specs?
Yes. The Tightening Torque for Bolts and Nuts section lists main bolt and nut torques, including the three-stage cylinder head sequence with separate figures for new and used bolts, plus fuel system fittings and standard bolt torques. p. 364
Can it help me diagnose alarms and trouble codes?
Yes. The Troubleshooting section starts from the trouble symptom, then covers fuse troubleshooting, the list of diagnostic trouble codes, temperature and pressure sensor diagnosis, wiring diagrams, and the ECU connector pin configuration for the electronic control system. p. 76
Where are the valve clearances and service standards?
The Service Standards section collects the tuning figures: intake valve clearance 0.15-0.25 mm, exhaust 0.45-0.55 mm, injection nozzle opening pressure, lube oil pressure, thermostat opening temperature, and the engine body wear limits, all in one place. p. 358
Is this Service Manual a digital download?
This is a 366-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.
Can I print just the pages I need 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 manual have electrical diagrams?
Yes. The wiring diagram is on page 331, and the Troubleshooting section adds the electrical side you actually use it with - fuse troubleshooting, the diagnostic trouble code list, and temperature and pressure sensor diagnosis. There is no separate connector-pinout material beyond that.
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