Yanmar Marine Auxiliary Diesel Engine & Generator Overhaul Service

BLUF: MarineListing provides 24/7 Class-certified major overhauls, in-situ machining, and genuine spare parts supply for Yanmar medium-speed auxiliary diesel engines and marine generator sets across all major global shipping corridors. Specializing in the Yanmar EY-series (6EY18ALW, 6EY22ALW, 6EY26AW, 6EY33BW) and N-series (6N21AU, 6N18AL), our factory-trained diesel riding squads and certified marine engine fitters execute complete 10,000-hour top overhauls and 20,000-hour major dockside or voyage refurbishments. Every overhaul strictly adheres to maker tolerances, IACS Class rules, and SOLAS Chapter II-1 mandates, covering cylinder liner 6-point micrometer ovality gauging, portable plateau diamond honing, piston crown ultrasonic NDT, tri-metal big-end bearing clearance measurement, fuel injection pump calibration, and optical crankshaft web deflection alignment across Singapore, Rotterdam, Fujairah, Houston, and Busan.

1. Statutory Mandates, Classification Rules & Class Survey Rigor

Auxiliary diesel generator engines are the beating heart of commercial shipboard operations, providing uninterrupted electrical power for propulsion thrusters, cargo refrigeration, steering hydraulics, navigation electronics, and safety systems. An uncontained auxiliary engine casualty—such as crankcase explosion, connecting rod bolt shear, or piston seizure—causes catastrophic total blackout, vessel drift, and immediate Port State Control (Paris MoU, USCG) detention.

+----------------------------------------------------------------------------------------------------+
|                                    GLOBAL MARINE ENGINE STATUTORY FRAMEWORK                        |
+----------------------------------------------------------------------------------------------------+
|  SOLAS Chapter II-1, Reg 26 & 27--> Reliability of machinery installations and electrical power    |
|  SOLAS Chapter II-1, Reg 41    --> Main source of electrical power and generator redundancy        |
|  IACS Unified Requirement M44  --> Overhaul and survey of marine internal combustion engines       |
|  MARPOL Annex VI, Reg 13       --> NOx Technical Code 2008 on-engine certification and EIAPP       |
|  ISO 3046-1                    --> Reciprocating internal combustion engines - Performance         |
|  CIMAC Recommendations         --> Guidelines for diesel engine exhaust emissions & lubrication    |
+----------------------------------------------------------------------------------------------------+

Statutory Overhaul Intervals & Class Survey Criteria

• 10,000 to 12,000 Operating Hours (Intermediate Top Overhaul):
  • Extraction and decoking of cylinder heads, intake/exhaust valves, and rocker arm assemblies.
  • Overhaul and hydro-testing of starting air valves and cylinder relief valves ($1.5\times\text{ opening pressure}$).
  • Ultrasonic cleaning, pop-pressure testing, and spray atomization verification of all fuel injection nozzles.
• 20,000 to 24,000 Operating Hours (Continuous Machinery Survey - CMS Major Overhaul):
  • Complete pulling of all pistons, connecting rods, and cylinder liners for dimensional calibration.
  • Non-destructive testing (NDT / Magnetic Particle Inspection per ASTM E1444) of connecting rod shank bodies, serrated parting faces, and high-tensile rod bolts.
  • Replacement of upper and lower tri-metal connecting rod large-end bearing shells.
  • Dimensional inspection and clearance measurement of main crankshaft journal bearings.
• MARPOL Annex VI NOx Technical Code Compliance:
  • Post-overhaul timing must preserve the engine's original Engine International Air Pollution Prevention (EIAPP) certificate parameters. Fuel injection timing ($^\circ\text{BTDC}$) must match the Technical File nameplate stamp.

Classification Society Rigor & Sign-Off Criteria

2. Technical Architecture, Mechanical Tolerances & Failure Modes

The Yanmar EY-series (e.g., 6EY18ALW, 6EY22ALW, 6EY26AW) represents modern high-efficiency, heavy-fuel-capable marine auxiliary engines featuring 4-valve cylinder heads, monobloc ductile iron engine frames, modular unitized fuel injection pumps, and high-efficiency axial turbochargers.

                    YANMAR 6EY26AW AUXILIARY ENGINE CROSS-SECTION
+----------------------------------------------------------------------------------+
|                                                                                  |
|                        [ 4-VALVE WATER-COOLED CYLINDER HEAD ]                    |
|                        Dual Intake / Nimonic Alloy Exhaust Valves                |
|                        Central High-Pressure Fuel Injector (30 MPa)              |
|                                       |                                          |
|                +----------------------------------------------+                  |
|                |            DUCTILE CAST IRON ENGINE BLOCK    |                  |
|                |  +----------------------------------------+  |                  |
|                |  |       BORE-COOLED CYLINDER LINER       |  |                  |
|                |  |  +----------------------------------+  |  |                  |
|                |  |  |    STEEL CROWN PISTON (NODULAR)  |  |  |                  |
|                |  |  |    3x Compression + 1x Oil Ring  |  |  |                  |
|                |  |  |                 |                |  |  |                  |
|                |  |  |   [ GUDGEON PIN & BUSHING ]      |  |  |                  |
|                |  |  +----------------------------------+  |  |                  |
|                |  |                                        |  |                  |
|                |  |   [ H-BEAM FORGED STEEL CON-ROD ]      |  |                  |
|                |  |   Diagonal Serrated Split Big-End      |  |                  |
|                |  +----------------------------------------+  |                  |
|                |                      |                       |                  |
|                |    [ TRI-METAL PRECISION BEARING SHELLS ]    |                  |
|                |    [ UNDERHUNG ALLOY STEEL CRANKSHAFT ]      |                  |
|                +----------------------------------------------+                  |
|                                       |                                          |
|                [ WET SUMP LUBRICATING OIL SYSTEM & PUMPS ]                       |
|                                                                                  |
+----------------------------------------------------------------------------------+

Critical Dimensional Tolerances & Mathematical Checks

1. Cylinder Liner Wear & Ovality Criterion: Liner wear is evaluated at 6 vertical planes along the piston stroke (top ring turnaround point $P_1$ through bottom dead center $P_6$), across both fore-aft and port-starboard axes: $$\text{Wear Rate} = \frac{\Delta D_{max}}{\text{Operating Hours} / 1000} \le 0.015\text{ mm per } 1000\text{ hours}$$ Maximum permissible total ovality/wear limit is $\Delta D \le 0.15\text{ mm}$ for 6EY18 and $\le 0.22\text{ mm}$ for 6EY26. Exceeding these limits causes severe blow-by, lube oil carbonization, and scuffing.
2. Crankshaft Web Deflection Alignment: Measured between crank webs using an acoustic or mechanical dial gauge across 5 angular positions: Bottom Dead Center Port ($B_P$), Top Dead Center ($T$), Bottom Dead Center Starboard ($B_S$), Bottom ($B$), and Starboard Horizontal ($S$): $$\Delta_{vertical} = |T - B| \le 0.040\text{ mm} \quad (\text{Alignment criteria for rigid bedplates})$$ Excessive web deflection indicates foundation resin choke degradation, hull deflection, or main bearing shell wear.

Diagnostic Fault Codes & Failure Modes

+---------------+-----------------------------+------------------------------------+---------------------------------------+
| Failure Mode  | Observed Symptom            | Root Cause Engineering Mechanism   | Corrective Action Protocol            |
+---------------+-----------------------------+------------------------------------+---------------------------------------+
| YAN-FAIL-01   | High Exhaust Temp Deviation | Clogged fuel injector nozzle spray | Pull injectors; ultrasonic clean; pop-|
|               | (> 45°C between cylinders)  | holes; eroded needle valve seat    | test to 30 MPa; lap needle valve seats|
+---------------+-----------------------------+------------------------------------+---------------------------------------+
| YAN-FAIL-02   | Heavy Blow-By / Crankcase   | Piston ring scuffing; stuck rings; | Pull piston; hone liner crosshatch;   |
|               | Overpressure (> 25 mmWC)    | bore polished cylinder liner       | fit genuine Yanmar chrome ring pack   |
+---------------+-----------------------------+------------------------------------+---------------------------------------+
| YAN-FAIL-03   | Low Lube Oil Pressure Trip  | Excessive big-end / main bearing   | Measure oil clearance with plastigage;|
|               | (< 0.35 MPa at full RPM)    | clearance; failed relief valve     | renew upper/lower tri-metal shells    |
+---------------+-----------------------------+------------------------------------+---------------------------------------+
| YAN-FAIL-04   | Engine Hunting on Load Step | Sluggish electronic governor ball- | Clean governor hydraulic oil sump;    |
|               | (> +/- 3.5% frequency drop) | joint linkage; sticky rack bushes  | replace governor actuator; lube rack  |
+---------------+-----------------------------+------------------------------------+---------------------------------------+
| YAN-FAIL-05   | Exhaust Smoke (Black/Grey)  | Late fuel injection timing; air    | Verify FIP spill-timing mark; clean   |
|               | under full electrical load  | charge air cooler fouled with soot | air cooler with chemical bath soak    |
+---------------+-----------------------------+------------------------------------+---------------------------------------+

3. Standard Operating Procedures: 20,000-Hour Major Engine Overhaul

MarineListing diesel engineering teams follow a certified 6-stage SOP for auxiliary engine major overhauls:

+----------------------------------------------------------------------------------------------------+
|                                    SOP FLOW: YANMAR AUXILIARY ENGINE MAJOR OVERHAUL                |
+----------------------------------------------------------------------------------------------------+
|  [STAGE 1]  --> Lockout/Tagout, Pre-Overhaul Deflection Log & Fluid Draining                       |
|  [STAGE 2]  --> Cylinder Head Stripping, Valve Guide Reaming & Hydrostatic Testing (7 bar)          |
|  [STAGE 3]  --> Piston Pulling, Decoking, NDT MPI Crack Testing & Ring Pack Renewal                 |
|  [STAGE 4]  --> Cylinder Liner Micrometer Calibration & In-Situ Diamond Plateau Honing             |
|  [STAGE 5]  --> Big-End Bearing Shell Renewal, Hydraulic Con-Rod Bolt Torquing & Web Deflection     |
|  [STAGE 6]  --> FIP Calibration, Fuel Spill-Timing Verification, Run-In & Load Bank Testing         |
+----------------------------------------------------------------------------------------------------+

Stage 1: Safety LOTO & Baseline Measurements

1. Lock out starting air master supply valve, fuel oil booster pump, and electrical breaker at the main switchboard. Engage engine turning gear.
2. Drain cooling fresh water jacket system and engine lube oil sump.
3. Take baseline "cold" crankshaft web deflections across all 6 cylinders using a calibrated Starrett dial gauge.

Stage 2: Cylinder Head Overhaul

1. Loosen hydraulic cylinder head nuts using Yanmar twin hydraulic tensioner rams ($P_{hyd} = 120\text{ MPa}$).
2. Lift cylinder heads with dedicated lifting beam. Strip valves, springs, and rotocaps.
3. Decoke gas passages. Measure valve stem-to-guide clearance using internal bore gauges:
   • Intake Guide Clearance: $0.05\text{ to }0.09\text{ mm}$
   • Exhaust Guide Clearance: $0.08\text{ to }0.12\text{ mm}$
4. Grind and lap valve seats with diamond lapping compound. Vacuum test seats ($> -0.8\text{ bar}$ holding vacuum). Hydro-test water jacket to $0.7\text{ MPa}$ ($7\text{ bar}$) for 30 minutes.

Stage 3: Piston Pulling & Ultrasonic NDT

1. Turn crank to BDC. Remove con-rod big-end bolts using hydraulic tensioner.
2. Guide piston and connecting rod assembly out through the cylinder bore using the maker guide sleeve.
3. Clean piston crowns in ultrasonic cleaning tank. Conduct Magnetic Particle Inspection (MPI per ASTM E1444) on the crown combustion bowl, ring lands, and con-rod shank to detect thermal fatigue micro-cracking.
4. Measure piston ring groove heights and ring end gaps inside the liner bore. Install new genuine Yanmar piston rings, ensuring correct orientation ("TOP" facing combustion chamber) and staggering ring gaps by $120^\circ$.

Stage 4: Cylinder Liner In-Situ Honing

1. Measure liner bore at 6 depths across fore-aft and port-starboard axes using an inside micrometer calibrated to $0.001\text{ mm}$.
2. If liner wear is within acceptable limits ($< 0.15\text{ mm}$) but exhibits bore glazing, mount the portable electro-pneumatic diamond honing machine.
3. Execute plateau honing using coarse diamond stones followed by silicone carbide brush finishing:
   • Target Crosshatch Angle: $45^\circ \pm 5^\circ$
   • Surface Roughness Target: $R_a = 0.4\text{ to }0.8\ \mu\text{m}$ (critical for rapid piston ring bed-in and oil retention).

Stage 5: Con-Rod Big-End Bearings & Crankshaft Deflection

1. Clean crankpin journals thoroughly. Check for ovality ($< 0.025\text{ mm}$) and surface scoring.
2. Install new genuine Yanmar tri-metal big-end bearing shells into the rod eye. Apply clean lubricating oil.
3. Check bearing running clearance using calibrated Plastigage: $$\text{Big-End Oil Clearance} = 0.090\text{ to }0.140\text{ mm for 6EY22/26}$$
4. Tighten con-rod high-tensile bolts crosswise using the certified hydraulic tensioner to the specified maker stretch or pressure ($P_{hyd} = 150\text{ MPa}$).
5. Re-record cold crankshaft web deflections across all units. Confirm maximum deflection $\Delta \le 0.040\text{ mm}$.

Stage 6: Fuel Timing, Run-In & Load Testing

1. Reinstall cylinder heads, rocker gear, and fuel injectors.
2. Verify fuel injection pump spill timing using high-pressure spill-timing tool: $$\text{Static Injection Timing} = 14.5^\circ \pm 0.5^\circ\text{ BTDC for 6EY26AW}$$
3. Prime lube oil system with external pre-lubrication pump until oil weeps from all rocker arms.
4. Execute manufacturer run-in schedule:
   • $25%\text{ Load}$ for 1 hour
   • $50%\text{ Load}$ for 2 hours
   • $75%\text{ Load}$ for 2 hours
   • $100%\text{ Full Load}$ for 1 hour
5. Measure peak firing pressures ($P_{max} \approx 18.5\text{ MPa}$) and exhaust temperatures across all cylinders. Deviation must remain within $\pm 25^\circ\text{C}$. Obtain Class surveyor final survey endorsement.

4. Engineering Specifications: Yanmar Marine Auxiliary Range

+----------------------------------------------------------------------------------------------------+
|                                    EQUIPMENT ENGINEERING SPECIFICATIONS                            |
+----------------------------------------------------------------------------------------------------+
|  Parameter                         | Yanmar 6EY18ALW                 | Yanmar 6EY26AW              |
+----------------------------------------------------------------------------------------------------+
|  Configuration                     | In-Line 6-Cylinder, 4-Stroke    | In-Line 6-Cylinder, 4-Stroke|
|  Cylinder Bore x Stroke            | 180 mm x 280 mm                 | 260 mm x 385 mm             |
|  Rated Continuous Output           | 600 kW to 800 kW @ 900/1000 RPM | 1500 kW to 2000 kW @ 720/750|
|  Mean Effective Pressure (BMEP)    | 2.14 MPa                        | 2.21 MPa                    |
|  Maximum Firing Pressure (Pmax)    | 16.5 MPa                        | 19.0 MPa                    |
|  Fuel Injection System             | High-Pressure Unitized Pump     | Monobloc High-Pressure Pump |
|  Fuel Capability                   | DMA, DMB, RMG 380, RMK 700 HFO  | RMK 700 Heavy Fuel Oil      |
|  Lube Oil Consumption Rate         | <= 0.8 g/kWh                    | <= 0.6 g/kWh                |
|  Dry Weight of Engine Only         | 7,200 kg (15,873 lbs)           | 17,500 kg (38,580 lbs)      |
|  NOx Emission Standard             | IMO Tier II / Tier III (SCR)    | IMO Tier II / Tier III (SCR)|
+----------------------------------------------------------------------------------------------------+

Table 1: Genuine Yanmar Spare Parts Stocking Matrix

5. Global Port Attendance, Shipyard Overhauls & Riding Squads

MarineListing maintains fully equipped diesel overhaul teams, portable in-situ boring/honing equipment, and certified Yanmar spare parts across major shipping centers.

+----------------------------------------------------------------------------------------------------+
|                                    GLOBAL MOBILIZATION COVERAGE                                    |
+----------------------------------------------------------------------------------------------------+
|  PORT HUB          | DEPOT LOCATION & WORKSHOP FACILITIES        | DISPATCH READINESS              |
+----------------------------------------------------------------------------------------------------+
|  Singapore         | Tuas Marine Engine Center & Loyang Depot    | Immediate (2 to 4 Hours OPL)    |
|  Rotterdam / ARA   | Schiedam Diesel Workshop & Europoort        | Same-Day (2 to 4 Hours)         |
|  Houston / US Gulf | Houston Ship Channel Diesel Repair Center   | 3 to 5 Hours Mobilization       |
|  Fujairah / UAE    | Fujairah Marine Technical Base & Dubai DMC  | 2 to 4 Hours via Launch Boat    |
|  Busan / S. Korea  | Gamcheon Engine Works Base                  | 2 to 4 Hours Mobilization       |
|  Suez Canal / EGY  | Port Said & Suez Maritime Workshop          | 4 to 6 Hours via Launch Boat    |
|  Shanghai / CN     | Pudong Marine Support Logistics Depot       | 3 to 5 Hours Mobilization       |
+----------------------------------------------------------------------------------------------------+

Turnkey Marine Auxiliary Overhaul Packages

• Voyage Riding Squads for Continuous Machinery Surveys:
  • Certified diesel fitters and tool containers embark at departure ports to overhaul 2 to 3 auxiliary generator engines sequentially during sea passages, eliminating all shipyard off-hire time.
• Emergency In-Situ Crankpin Machining:
  • Portable orbital orbital turning and micro-grinding machines deployed within 12 hours to machine scored or out-of-round crankpins in-situ down to $-0.50\text{ mm}$ or $-1.00\text{ mm}$ undersize.

6. Pre-Survey Verification Checklist

Vessel chief engineers, technical superintendents, and attending Class surveyors verify the following critical checkpoints:

[ ] COMPONENT DIMENSIONAL & NDT VERIFICATION
    [ ] Cylinder liner bore micrometer calibration logged at 6 levels (wear < 0.15 mm max).
    [ ] Magnetic Particle Inspection (MPI) confirms zero cracks on con-rod shanks and rod bolts.
    [ ] Piston ring end gaps and axial clearances verified within maker tolerances.
    [ ] Tri-metal big-end bearing clearance measured with Plastigage (0.090 to 0.140 mm).

[ ] ASSEMBLY & TORQUE INTEGRITY
    [ ] Connecting rod bolts tightened using calibrated hydraulic tensioner to 150 MPa pressure.
    [ ] Cylinder head hydraulic nuts torqued to specified pressure (120 MPa); zero gasket leakage.
    [ ] Crankshaft web deflections recorded cold and verified <= 0.040 mm across all cylinders.
    [ ] Fuel injection pump static spill timing confirmed to maker degree mark (+/- 0.5° BTDC).

[ ] OPERATIONAL RUN-IN & ELECTRICAL COMMISSIONING
    [ ] Lube oil system pre-lubricated; oil pressure reaches nominal >= 0.45 MPa before start.
    [ ] Run-in protocol executed sequentially from 25% to 100% full electrical generator load.
    [ ] Cylinder exhaust temperature deviations remain within +/- 25°C across all cylinders.
    [ ] Crankcase oil mist detector (OMD) and high-temperature safety shutdown alarms verified.

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