Overhaul Procedure of Turbocharger In Marine Diesel Engine Maintenance

Learn the complete overhaul procedure of a marine diesel engine turbocharger. Step-by-step maintenance, safety, tools, and best practices explained.

Overhaul Procedure of Turbocharger In Marine Diesel Engine

In modern marine diesel engines, the turbocharger is an indispensable component. By recovering exhaust gas energy and using it to compress intake air, it increases engine efficiency, reduces fuel consumption, and lowers emissions. Without a well-maintained turbocharger, the engine loses power, consumes more fuel, and risks breakdowns. This article, based on the provided training video, explains the overhaul procedure of a turbocharger while expanding it into a full maintenance guide for marine engineers. We will explore:

• The purpose and function of the turbocharger in ship engines.
• Step-by-step removal and mounting procedures.
• Critical overhaul tasks (cleaning, inspection, reassembly).
• Safety measures and best practices.
• Common problems and troubleshooting.
• Regulatory context and class society requirements.

By the end, you will have a complete, practical understanding of turbocharger overhaul and maintenance, essential for safe and efficient ship operations.

---

1. Understanding the Turbocharger in Marine Diesel Engines

What Is a Turbocharger?

A turbocharger is a turbine-driven air compressor. It consists of:

• Turbine side: driven by hot exhaust gases.

• Compressor side: compresses incoming air, sending it to the engine cylinders.

This process increases the mass of air inside the cylinder, enabling more fuel to burn efficiently, thus generating higher power output without increasing cylinder size.

 Role in Marine Engines

• Improves fuel efficiency – more power from the same fuel.

• Reduces emissions – complete combustion lowers smoke and NOx.

• Enables compact design – higher output from smaller engines.

---

2. Why Turbocharger Maintenance Is Essential

Turbochargers operate under extreme conditions: turbine blades face hot gases at 500–600°C, while compressor impellers rotate at 10,000–20,000 rpm.

Failure to maintain them can cause:

• Power loss (dirty turbine blades).

• Bearing failure (oil contamination or starvation).

• Excessive vibration (imbalanced rotor).

• Engine damage (scavenge fire, piston crown failure).

Regular overhaul and cleaning prevent such risks and ensure compliance with SOLAS Chapter II-1 and class society rules.

---

3. Preparations Before Overhaul

Tools and Equipment Needed

• Standard spanners and sockets.

• Lifting gear / chain blocks.

• Torque wrench.

• Cleaning solvents and brushes.

• Anti-seize compound.

• New seals, O-rings, and V-rings.

Safety Measures

• Inform bridge/engine control room before work.

• Ensure turbocharger is cooled down.

• Isolate lube oil system (close inlet/outlet valves).

• Wear PPE (gloves, goggles, safety shoes).

---

4. Removal of Turbocharger – Step by Step

According to the video, the turbocharger removal sequence is:

1. Disconnect exhaust inlet and outlet – unbolt the connections, marking alignment.

2. Remove booster outlet (compressor discharge pipe).

3. Disconnect lube oil pipes – carefully plug to prevent contamination.

4. Remove attaching foot bolts.

5. Set lifting tool/chain block – secure properly to prevent damage.

6. Lift and remove the turbocharger – carefully maneuver to a clean workspace.

Tip: Always follow manufacturer’s guidelines (e.g., MET18SRC manual).

---

5. Overhaul Procedure of Turbocharger

While the video refers to “separately check overhaul procedure for MET turbo,” here we expand on typical overhaul practices.

Disassembly

• Remove compressor cover.

• Extract compressor impeller (mark orientation).

• Remove turbine casing and nozzle ring.

• Take out rotor shaft assembly with bearings.

Inspection

• Turbine blades: check for cracks, corrosion, deposits.

• Compressor impeller: check for fouling, erosion.

• Bearings and thrust collar: measure clearances.

• Seals (O-rings, V-rings): replace if hardened or worn.

• Nozzle ring: inspect guide vanes for blockage or erosion.

Cleaning

• Wash turbine/compressor components with suitable solvent.

• Remove carbon deposits with soft brushes.

• Avoid aggressive scraping (to protect blade profiles).

Balancing

The rotor assembly must be dynamically balanced to avoid vibrations. Many ships send rotors to workshops for balancing, but small checks can be made onboard.

Reassembly

• Fit new seals (O-rings, V-rings, packings).

• Grease bearings with approved oil.

• Reassemble in reverse order, ensuring alignment marks match.

---

6. Mounting the Overhauled Turbocharger

The video describes this sequence:

1. Fit new V-ring, O-ring, and packings.

2. Lower turbocharger into position using lifting gear.

3. Tighten attaching foot bolts.

4. Apply anti-seize compound to exhaust inlet/outlet bolts.

5. Insert new packings and tighten connections.

6. Reconnect lube oil pipe.

7. Finish with functional checks (oil priming, rotation by hand, no binding).

---

7. Testing After Overhaul

1. Pre-lubrication: Fill oil into bearings before starting engine.

2. Manual rotation: Ensure smooth, free turning.

3. Engine run-up: Start engine slowly, monitor:

   • Oil pressure to turbocharger.

   • Exhaust gas temperature.

   • Vibration/noise levels.

4. Logbook entry: Record overhaul details, parts replaced, test results.

---

Common Turbocharger Problems and Troubleshooting

• Excessive smoke: May indicate fouled turbine or leaking seals.

• High exhaust temperature: Possible nozzle ring fouling.

• Oil leakage: Damaged seals or clogged drain.

• Unusual vibration: Rotor imbalance or bearing wear.

Timely overhaul prevents escalation of these issues.

Best Practices for Engineers

• Follow maker’s manual for intervals and procedures.

• Keep spare seals and gaskets in stock.

• Use only approved oils and cleaning solvents.

• Conduct regular turbine/compressor washing (water washing, dry cleaning).

• Always log maintenance activities.

Conclusion

The turbocharger is a critical component of marine diesel engines, directly impacting power, efficiency, and emissions. As the training video demonstrates, correct removal, overhaul, and mounting procedures ensure reliability and compliance with maritime regulations.

By expanding on the core content, we have covered detailed steps for disassembly, inspection, cleaning, reassembly, and testing. With proper maintenance culture, marine engineers can extend turbocharger life, prevent costly breakdowns, and keep ships running safely across the oceans.