Part of the Yanmar Repair Manuals.
Coolant weeping from the block overflow holes on a Yanmar SY series diesel means a cylinder liner O-ring has let go, and oil from the same holes points to a liner shelf leak. That diagnosis, and the liner, piston, and crankshaft work that follows it, is exactly what this service manual exists for. It covers the Yanmar 6SY-STP2 and 6SY655 (11.7 L) and the 8SY-STP (15.6 L) marine engines in a 278 page English PDF, Yanmar publication 0BSYM-G00100.
The Engine chapter carries the cylinder head, pistons and liners, timing gear train, and crankshaft. Separate chapters handle unit injector adjustment, the cooling system with its seawater pump and zinc anodes, lubrication, the turbocharger, starter motor, alternator, EMS sensors, and a troubleshooting chart with fault codes. Valve lash, test pressures, and torque values sit where each procedure needs them, so the numbers are in hand before the head goes back on.
Complete the set for your 6SY-STP2, 6SY655, 8SY-STP
- Repair Manual: Yanmar 8SY-STP, 8SY Marine Engines Operation Manual
What's Inside This Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 5-6 | Manual Purpose, Quality Service, Special Tools, Product Improvement Policy, Revision History |
| Safety | 7-12 | |
| General Service Information | 13-32 | Engine Outline Drawings, Engine Piping Diagrams, Location of Nameplates, Diesel Fuel Specifications, Engine Oil Specifications, Engine Coolant Specifications |
| Periodic Maintenance | 33-42 | Importance of Periodic Maintenance, Performing Maintenance, Yanmar Replacement Parts, Epa Requirements (Usa Only), Periodic Maintenance Schedule |
| Engine | 43-136 | Cylinder Head Components, Pistons and Cylinder Liners, Flywheel and Flywheel Housing, Timing Gear Train, Cylinder Block and Crankshaft, Exhaust Manifold |
| Fuel System | 137-154 | Fuel Delivery Components, Fuel Injector Components, Adjust Unit Injectors, Measure Fuel Feed Pump Pressure, Replace Fuel Filter, Bleed Fuel System |
| Cooling System | 155-184 | Pressure Testing Cooling System, Testing the Thermostat, Coolant Pump removal/installation, Seawater Pump, check/replace Zinc Anodes |
| Lubrication | 185-200 | Check Engine Oil Pressure, remove/install Oil Cooler, remove/install Oil Cleaning Components, Replace Engine Oil Filter, Clean Centrifugal Oil Cleaner, Oil Pump |
| Turbocharger | 201-214 | General Information, Component Location, Measuring Charge Pressure, Remove Turbocharger, Inspect Turbocharger, Measure Radial and Axial Clearance |
| Starter Motor | 215-226 | Starter Motor Specifications, Starter Motor Troubleshooting, remove/install Starter Motor, Repair Starter Motor (Bosch Je), Brush Replacement, Replace Solenoid |
| Alternator | 227-236 | Alternator Specifications, Calculating Alternator Capacity, Alternator and Charging System Troubleshooting, Output Test, Brush Length, Replace Alternator Belt |
| Ems | 237-260 | Function Description, Component Location, Engine Speed Sensors, Charge Air Pressure and Temperature Sensor, Coolant Temperature Sensor, Oil Pressure Sensor |
| Troubleshooting | 261-278 | Troubleshooting Chart, Fault Codes, Working Procedure, After Troubleshooting or Repair |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| 8SY | ||
| Turbocharger-to-Exhaust Manifold Bolt Torque, 8SY | 63 N·m (46 ft-lb) | p. 204 |
| All Models | ||
| Coolant Pump Impeller Installation Distance | 13.3 - 13.7 mm (0.524 - 0.539 in.) | p. 158 |
| Turbocharger-to-Exhaust Pipe Bolt Torque | 24 N·m (212 in.-lb) | p. 204 |
| Compression Ratio | 16:1 | p. 27 |
| Battery Capacity - Recommended | 160 Ah | p. 27 |
| Intake Valve Clearance | 0.45 mm (0.018 in.) | p. 29 |
| Exhaust Valve Clearance | 0.70 mm (0.028 in.) | p. 29 |
| 6SY | ||
| Turbocharger-to-Exhaust Manifold Bolt Torque, 6SY | 50 N·m (37 ft-lb) | p. 204 |
| 6SY-STP2/6SY655 | ||
| Engine Displacement, 6SY-STP2/6SY655 | 11.7 L (714 cu in.) | p. 27 |
| Coolant capacity with coolant recovery tank, 6SY-STP2/6SY655 | 40 L (10.5 gal) | p. 27 |
| 8SY-STP | ||
| Engine Displacement, 8SY-STP | 15.6 L (952 cu in.) | p. 27 |
| Coolant capacity with coolant recovery tank, 8SY-STP | 75 L (20 gal) | p. 27 |
