Need the factory procedures for your marine power plant? All 278 pages of this Yanmar 6SY-STP2, 6SY655, 8SY-STP service manual PDF (OEM #0BSYM-G00100) focus on tearing down, diagnosing, and rebuilding these heavy-duty marine engines. Inside, you get a full electrical system breakdown with clear wiring diagrams, direct fault code troubleshooting tables, and complete turbocharger testing protocols. Open to the cooling system chapter to find step-by-step instructions for pressure testing, thermostat checks, and complete seawater pump overhauls. Press the new coolant pump impeller to an exact installation distance of 13.3 to 13.7 mm, and remember to torque the 8SY turbocharger-to-exhaust manifold bolts to 63 N-m. Don't risk a breakdown offshore because of bad forum advice. Download this bookmarked file directly to your laptop or phone, search by keyword, and get back on the water.
What's Inside This Yanmar 6SY-STP2, 6SY655, 8SY-STP 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 | 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 | 50 N·m (37 ft-lb) | p. 204 |
| 6SY-STP2/6SY655 | ||
| Engine Displacement | 11.7 L (714 cu in.) | p. 27 |
| Coolant capacity with coolant recovery tank | 40 L (10.5 gal) | p. 27 |
| 8SY-STP | ||
| Engine Displacement | 15.6 L (952 cu in.) | p. 27 |
| Coolant capacity with coolant recovery tank | 75 L (20 gal) | p. 27 |
Yanmar 6SY-STP2, 6SY655, 8SY-STP Common Problems This Manual Covers
Yanmar 6SY-STP2 marine engine coolant loss and visible seepage from the coolant pump assembly p. 158
Inspect the coolant pump assembly for seal failure. Remove the pump and measure the impeller installation distance. Press the new impeller onto the shaft until the clearance is exactly 13.3 - 13.7 mm (0.524 - 0.539 in.) as specified on page 158. Replace the entire assembly if housing wear exists.
Manual Section: Cooling SystemEngine cranks normally but experiences fuel starvation and hard starting with no fuel at the injector lines p. 29
Measure the fuel feed pump pressure at 500 rpm. If pressure drops below the minimum 4.5 bar (65 psi) listed on page 29, check the fuel filter and water separator for contamination. Drain any water, bleed the fuel system, and retest to verify adequate delivery to the unit injectors.
Manual Section: Fuel SystemWet exhaust and weak compression after internal corrosion occurs inside the exhaust elbow p. 204
Remove and inspect the exhaust elbow for seawater intrusion. When installing the replacement components on an 8SY model, torque the turbocharger-to-exhaust manifold bolts to 63 N·m (46 ft-lb) using the specifications on page 204. Secure the exhaust pipe bolts to 24 N·m (212 in.-lb) to prevent future exhaust leaks.
Manual Section: TurbochargerVisible coolant or oil leaking directly from the cylinder block overflow holes p. 29
Pressure test the cooling system to 0.4 - 0.5 bar (5.8 - 7.3 psi) as detailed on page 29. Coolant from the overflow indicates a failed cylinder-liner O-ring, while oil points to a liner shelf leak. Drain the fluids and remove the affected pistons and cylinder liners for inspection.
Manual Section: TroubleshootingFrequently Asked Questions
What are the torque specifications for Yanmar 6SY-STP2 cylinder head bolts?
The cylinder head bolts require a four-stage tightening process. First, tighten to 60 N·m (44 ft-lb), then to 150 N·m (110 ft-lb), followed by 250 N·m (184 ft-lb), and finally an additional 90° turn. These specifications are crucial for proper assembly.
What is the service procedure for a Yanmar 8SY-STP fault code?
When a fault code is displayed, consult the publication supplied with the unit for interpretation. The general working procedure involves gathering information on fault symptoms, conditions, and frequency, then presenting stored fault codes to determine the probable cause. After troubleshooting or repair, ensure to check and clear any generated fault codes from the engine control unit.
What are the recommended engine oil specifications and viscosity for Yanmar SY series marine engines?
Yanmar SY series marine engines require engine oil that meets or exceeds API Service Categories CD or higher, ACEA Service Categories E-3, E-4, E-5, or JASO Service Category DH-1. The recommended oil viscosity is SAE 15W40, but the appropriate viscosity should be selected based on the ambient operating temperature, as detailed in the SAE Service Grade Viscosity Chart.
What are the coolant specifications and capacity for the Yanmar 6SY-STP2 and 8SY-STP engines?
For Yanmar SY series engines, use a Long Life Coolant (LLC) meeting ASTM D6210, D4985, JIS K-2234, or SAE J814C, J1941, J1034, J2036 specifications, with a concentration of 30% to 60%. The coolant capacity with the recovery tank is 40 L (10.5 gal) for 6SY engines and 75 L (20 gal) for 8SY engines.
How quickly can I access this manual after?
This is a 278-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 manual have electrical diagrams?
Complete wiring diagrams are included, covering all electrical circuits, harness routing, and connector pinouts for the Yanmar 6SY-STP2, 6SY655, 8SY-STP.
Document Quality
This document is a native digital PDF, allowing you to search and copy all text. The text throughout is consistently crisp and easy to read. Diagrams and illustrations are primarily sharp line drawings, ensuring labels are clear and details are visible at any zoom level. Some engine photos are clear raster images. Pages are clean with no noticeable scan artifacts, stains, or skewed content. There are several intentionally blank pages used as section separators or filler.
Reviews
There are no reviews yet.