Neptunus Power Plant Services Pvt. Ltd.
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AUXILIARY ENGINE
REPAIR & OVERHAUL
SERVICES

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OEM-Trained Engineers
30% Faster
Turnaround Time
vs. OEM
Benchmark
30% Cost Reduction
with technology,
maintaining
reliability until the
next overhaul
Timely
Deployment
(Access to
Multiple
PRs & CDC)
Comprehensive
Support On-site,
Off-site, Remote,
including
Riding Squad
12-Month
Workmanship
Warranty
Access to Specialized
Tools such as Chris
Marine Cylinder Liner
Honing, Valve Seat
Machining Tool
Adherence to
OEM Standards
Detailed
Work Completion
Report
View Reports

Auxiliary engine services are essential for maintaining the reliability and efficiency of a vessel’s onboard power systems. Auxiliary engines support critical operations such as electricity generation, pumps, compressors, and other vital equipment required for safe vessel operation.

At Neptunus Power we provide comprehensive auxiliary engine repair and overhaul services designed to ensure optimal performance, reduced downtime, and extended engine life.

With over 30 years of marine engineering experience, our team of 27+ highly skilled engineers, including dedicated auxiliary engine specialists, delivers professional repair, troubleshooting, maintenance, and overhaul services for a wide range of marine auxiliary engines.

Our engineers have extensive expertise working with major marine engine manufacturers, including Niigata (OEM), EMD (OEM), Caterpillar, MAN, Wärtsilä and Yanmar. We have successfully completed numerous auxiliary engine repair projects for different vessel types across the marine industry, establishing a strong reputation for technical expertise and reliable service delivery.

Neptunus provides global auxiliary engine service support, assisting vessel operators across major maritime regions including South Asia, the Middle East, Europe, and Africa. Within India, our service teams regularly support vessels in key maritime hubs such as Mumbai, Cochin, Goa, Kolkata, Chennai, Visakhapatnam and Haldia.

Our riding squad of engineering teams can travel worldwide to provide onboard auxiliary engine inspection, troubleshooting, repair, and major overhaul services, helping ship operators minimise operational downtime and maintain efficient vessel performance.

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Why choose Neptunus?

3 Decades of
Service Excellence
Engine & Propulsion
End-to-End Solutions
2500+ Successful Projects Delivered Worldwide
Trusted by 100+
Satisfied Customers
Dedicated Experts to Address Emergencies

Track Record of Job Completion on or Before Planned Timeline

Detailed Post-Service Tests and Sea-Trails to Ensure Quality

Challenges in Auxiliary Engine Repair & Overhaul Services

  • 1. Integration Challenges:
    Auxiliary engines are interconnected with various ship systems. Repairing one component may affect others, requiring careful coordination to ensure all systems work together seamlessly after repairs.
  • 2. Diagnostic Issues:
    Identifying the exact problem with an auxiliary engine can be challenging. Since these engines power various systems, a malfunction could stem from multiple sources. Thorough diagnostic procedures and testing are required to pinpoint the issue accurately.
  • 3. Downtime Costs:
    When an auxiliary engine is down for repairs, it can mean a loss of productivity or even a safety hazard. This puts pressure on technicians to complete repairs quickly, which can lead to mistakes.
  • 4. Part Availability:
    Finding replacement parts for auxiliary engines, especially older models, can be difficult and time-consuming. There may not be a large stock of spare parts for auxiliary engines on hand, and ordering them can lead to delays.

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Process of Auxiliary Engine Overhauls

Auxiliary engine overhaul services are essential for maintaining the reliability, efficiency, and operational safety of marine engines. A structured overhaul process helps identify wear, prevent unexpected breakdowns, and restore engine performance to manufacturer standards. From inspection and disassembly to testing and recommissioning, every stage plays a critical role in extending engine life and reducing downtime. For ship owners facing performance issues or recurring faults, professional diesel engine services can help ensure long-term operational reliability.

1. Preparation and Pre-Disassembly

  • Reviewing the Job Order:
    We begin by thoroughly reviewing the job order, understanding the reported issues, and referencing the engine's technical manual. This equips us with the necessary knowledge and procedures.
  • Safety First:
    We conduct a safety briefing, ensuring everyone understands the hazards involved and dons the appropriate Personal Protective Equipment (PPE) like gloves, safety glasses, and steel-toed boots.
  • Isolating and Lockout/Tagout:
    We isolate the engine from its fuel, electrical, and cooling systems. We then implement a Lockout/Tagout procedure to prevent accidental energization or startup.
  • External Inspection and Documentation:
    We give the engine a thorough visual examination, documenting any external damages, leaks, or loose components. Photos are often taken for reference during reassembly.

2. Disassembly

  • Draining Fluids:
    We drain the engine oil, coolant, and fuel into designated containers for proper disposal. Oil samples might be taken for analysis to identify wear patterns.
  • Peripheral Removal:
    We systematically remove all peripheral components like the radiator, air intake system, exhaust manifold, and alternator. These are tagged and stored securely.
  • Top-End Disassembly:
    We move on to the top-end by removing the valve cover, rocker arms, and pushrods. This exposes the cylinder head for further disassembly.
  • Cylinder Head Removal:
    Following the manufacturer's instructions, we carefully remove the cylinder head bolts and lift the head off the engine block. Gaskets and any sticking components are addressed meticulously.

3. Cleaning and Inspection

  • Degreasing and Cleaning:
    All disassembled components are thoroughly degreased and cleaned using appropriate solvents and parts washers. This allows for a clear inspection of their condition.
  • Detailed Inspection:
    Each component undergoes a meticulous inspection. We check for wear on pistons, rings, bearings, and cylinder liners. Cracks or deformations are diligently looked for. The service manual's specifications guide our assessment.
  • Measurements and Gauging:
    We use precision measuring tools and gauges to assess clearances, wear, and tolerances of critical components. This helps determine if parts need replacement or reconditioning.

4. Overhaul and Reassembly

  • Replacement or Repair:
    Based on the inspection results, we replace worn-out components with new parts or recondition salvageable ones within manufacturer's specifications.
  • Honing and Machining:
    If necessary, the cylinder liners might be honed to restore proper surface finish. Certain components, like crankshafts might require machining for rectification.
  • Gasket and Seal Replacement:
    All old gaskets and seals are replaced with new ones to ensure proper sealing and prevent leaks upon reassembly.
  • Reassembly Sequence:
    Following the service manual in reverse order, we reassemble the engine. Torque specifications are strictly adhered to for proper fit and function.

5. Finalization and Testing

  • Reinstallation of Peripherals:
    All previously removed peripheral components like the radiator, exhaust system, and alternator are reinstalled and secured.
  • Filling Fluids and Initial Checks:
    Fresh engine oil, coolant, and fuel are added following the manufacturer's recommended capacities. We perform initial checks for leaks and proper fluid circulation.
  • Electrical System Reconnection:
    The engine's electrical system is carefully reconnected, ensuring all connections are secure and free of damage.
  • Engine Start-up and Testing:
    We follow the manufacturer's starting procedures and cautiously crank the engine. Once running, we meticulously monitor oil pressure, coolant temperature, and exhaust emissions to ensure proper operation.
  • Final Adjustments and Documentation:
    Any minor adjustments are made for optimal performance. All replaced parts, measurements, and observations are documented for future reference.
  • Handover and Documentation:
    The engine is handed back over to the client, with a detailed report outlining the work performed, replaced parts, and any recommendations for future maintenance.

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Marine Engine Brands For Which We Provide Repair & Overhaul Service

Niigata Engine Repair and Overhaul Services
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EMD Engine Repair and Overhaul Services
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CAT Engine Repair and Overhaul Services
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Yanmar Engine Repair and Overhaul Services
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Wartsila Engine Repair and Overhaul Services
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MAN Engine Repair and Overhaul Services
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MTU Engine Repair and Overhaul Services
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This page has been technically reviewed by the engineering leadership team at Neptunus Power Plant Services Pvt. Ltd.
Last Updated: May 2026

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