MAN BW Engine Maintenance is paramount for ensuring their efficiency, reliability, and extended operational life. These high-performance marine diesel engines are the backbone of many vessels, and their proper upkeep demands meticulous attention to detail across various components, from cylinder liners to sophisticated cooling systems. This comprehensive guide aims to provide an updated and in-depth breakdown of essential maintenance procedures for MAN B&W engines, incorporating best practices and recent advancements to ensure peak performance, minimize downtime, and enhance overall operational effectiveness. Whether you are conducting routine inspections or preparing for major overhauls, this enhanced maintenance checklist will serve as an invaluable resource.
Understanding MAN BW Engine Maintenance Schedules
MAN B&W engines, particularly the common rail variants introduced around 2005, are renowned for their advanced technology, fuel efficiency, reduced vibration, and lower noise levels. While some perceptions suggest these engines require more intensive and costly maintenance, recent updates, especially with the latest V8 and V12 iterations, have streamlined service intervals. Notably, the shift from tank and bundle engine cooling systems to more robust plate cooling systems in 2018 has extended cooling system service requirements from every two years to every four years, significantly reducing maintenance frequency and costs [1].
Regular maintenance is categorized by running hours or chronological intervals, ensuring that all components function efficiently and preventing unexpected failures. The following sections detail a comprehensive maintenance schedule, building upon the original blog post’s structure and integrating additional insights.
Detailed Maintenance Procedures by Component and Interval
Here is a comprehensive engine maintenance schedule in table format, including major intervals and time-between-overhaul (TBO)/inspection hours for typical marine diesels (adapting from your MAN L28/32H sample):
| Maintenance Task | Component/System | Frequency/Interval (Whichever Sooner) |
|---|---|---|
| Check readings/data, log performance | All (general) | Daily |
| Visual inspection | All (general) | Daily |
| Drain air system, check water/fuel/oil | Air/compressor/lubrication | Daily |
| Check lube oil/cooling water levels | Lube/cooling system | Daily/Weekly |
| Lube forced lubrication points | All (journal/gears etc.) | Weekly |
| Water sample/corrosion analysis | Cooling system | Monthly |
| Change filters: Fuel/lube/air | Fuel/lube/air systems | 200 hours/monthly/condition-based |
| Full filter cleaning/centrifuge replace | Lube/fuel system | 200/600/2000/6000 hrs |
| Cylinder head: Inspect, retighten, valve regrind | Cylinder head | 6000/12000/24000 hrs & as needed |
| Cylinder liner: Inspect, measure, hone, clean | Cylinder liner | 6000/12000/24000 hrs |
| Piston, rings: Inspect, renew, decarbonize | Piston group | 6000/12000/24000 hrs |
| Connecting rod: Small/Big end inspect/retighten | Conrod/Piston assembly | 6000/12000/24000 hrs |
| Camshaft drive/bearings: Inspect, lube, check gears | Camshaft/drive | 200 hrs/6000/12000/24000 hrs |
| Main/guides: Align, retighten, measure, overhaul | Main/guide bearings | 6000/12000/24000 hrs |
| Turbocharger: Clean, inspect, overhaul, replace | Turbocharger | Monthly/6000/12000/24000 hrs/manual |
| Air cooler: Clean, drain housing/check | Charging air cooler | Monthly/6000/Annual |
| Fuel system: Clean pumps/filters/adjust/nozzles | Fuel delivery/injection | 200/600/12000/24000 hrs |
| Governor: Check oil, function, overhaul | Governor | 6000/12000/24000 hrs (see manual) |
| Exhaust system: Inspect/cooler/compensator | Exhaust system | 6000/12000/24000 hrs |
| Lubricating system: Overhaul/service all pumps | Lube oil system | 6000/12000/24000 hrs |
| Cooling water system: Pump overhaul, thermostat | CW System | 6000/12000/24000 hrs |
| Crankshaft TBO/intermediate overhaul | Crankshaft | 24000 hrs (major overhaul) |
| Safety, Alarm & Automation: Test & adjust | Engine controls/safety | Weekly/Monthly/6000/Annual |
Notes:
- Always refer to the engine’s OEM or official register for specific intervals per class/type.
- “As needed” applies based on condition monitoring and operational history.
- Replace/renew/overhaul intervals (hours) are typical for MAN L28/32H-type, similar for many other marine engines, but always check vessel-specific manuals.
Hourly Scheduled Maintenance (0 – 16,000 Hours)
Cylinder Liner
1.Dismantle and Inspect: Thoroughly dismantle and inspect all cylinder liners for wear, scoring, or any abnormalities.
2.Honing: Hone the cylinder liners to restore their surface integrity and optimize oil retention.
3.Measurement and Recording: Accurately record measurements of cylinder liners to track wear patterns and predict future maintenance needs.
Piston and Piston Rings
1.Withdrawal and Overhaul: Withdraw all pistons for comprehensive inspection and overhaul.
2.Decarbonization: Decarbonize pistons to remove carbon deposits that can impede performance and cause wear.
3.Ring Groove Inspection: Clean piston and oil scraper ring grooves. Inspect for wear using a testing mandrel to ensure they meet acceptable tolerances.
4.Ring Replacement: Replace all piston and scraper rings before reinstalling pistons, ensuring optimal sealing and compression.
5.Positioning: Confirm piston ring positions are offset 180° from each other, and ensure the scraper ring spring joint is fitted 180° offset to the ring joint for proper function.
6.Plug Maintenance: Open all plugs and apply new Loctite 2701 after cleaning holes and plugs with Loctite 7063. Tighten plugs to a torque of 100Nm.
7.Piston Pin Testing: Perform ultrasonic testing of piston pins (typically by an external agency) to detect any internal flaws or fatigue.
8.Retaining Ring Change: Change retaining rings for all pistons to secure the piston pins effectively.
Connecting Rod
1.Big-End Bore Inspection: Inspect and measure the big-end bore diameter for any deformation or wear.
2.Small-End Bearing Inspection: Inspect small-end bearings and check clearance between the piston pin and bush, documenting all readings.
3.Bolt and Nut Inspection: Visually inspect all connecting rod bolts and nuts for abnormalities such as cracks or stretching.
4.Machining Hole Tightness: Check the tightness of all machining holes and blank screws to prevent leaks or loosening.
Cylinder Heads
1.Removal and Cleaning: Remove and thoroughly clean all cylinder heads.
2.Valve Spindle Inspection: Inspect inlet and exhaust valve spindles, machining or replacing them as required to ensure proper seating and sealing.
3.Valve Rotator Check: Check valve rotators for proper rotation and repair/replace defective Robocap parts, including springs, balls, and pressure plates.
4.Safety Valve Overhaul: Overhaul safety valves and adjust the opening pressure to 175 bars to ensure engine protection.
5.Indicator Valve Inspection: Inspect indicator valves for proper function.
6.Valve Seat Maintenance: Inspect and machine/replace valve seats as necessary to maintain optimal valve sealing.
7.Pressure Testing: Perform pressure testing of all cylinder heads to detect any leaks or structural weaknesses.
8.Water Guide Jacket Maintenance: Remove, clean, and inspect water guide jackets, replacing O-rings as needed to prevent coolant leaks.
9.Nipple Inspection: Inspect and replace nipples as required.
10.Nut Tightening: Tighten cylinder head nuts to the prescribed torque for secure assembly.
Camshaft and Camshaft Bearings
1.Gear Wheel Inspection: Inspect gear wheels, bolts, and connections for abnormalities.
2.Bearing Clearance Measurement: Measure and record bearing clearances to monitor wear.
3.Cam Condition Check: Check the condition of cams for wear or damage.
4.Lubrication Verification: Verify proper lubrication of the camshaft, ensuring adequate oil flow from all bearings and spray pipe nozzles.
5.Fastener Tightness: Check the tightness of all screws, nuts, and bolts.
6.Push Rod Inspection: Inspect push rods for any signs of wear or bending.
7.Valve Clearance Adjustment: Adjust inlet valve clearance to 0.4mm and exhaust valve clearance to 0.9mm for optimal valve timing.
Operating Gear for Inlet Valves, Exhaust Valves, and Fuel Injection Pumps
1.Roller Guide Inspection (Valve Gear):
•Look for marks or scores due to seizure.
•Check for deformation on spherical studs.
•Inspect the surface of rollers for any marks or deformation.
•Ensure free play between rollers, bushes, and pins.
2.Spring and Arm Inspection: Inspect valve bridge springs, rocker arm brackets, and push rods for abnormalities.
3.Roller Guide Inspection (Fuel Injection Pumps):
•Check for marks or scores due to seizure.
•Inspect roller surfaces for marks or deformation.
•Ensure free play between rollers, bushes, and pins.
4.Lubrication Check: Check lubrication of all operating gears.
Governor
1.Drive Inspection: Inspect the governor drive.
2.Oil Change: Change the governor oil after flushing the system.
3.Linkage Tightening: Inspect and tighten linkages and foundation bolts.
4.Overhaul: Overhaul the governor (typically by an external agency) for precise speed control.
Crankshaft and Main Bearings
1.Crankpin Inspection: Inspect crankpins for wear or damage.
2.Main Bearing Alignment: Check main bearing alignment (using autolog) and realign the crankshaft if necessary.
3.Bearing Shell Replacement: Replace all main bearing shells, including guide bearings, to maintain proper clearances.
4.Counterweight Retightening: Retighten counterweights to a prescribed torque of 300Nm.
5.Bearing Cap Retightening: Retighten main and guide bearing caps to the prescribed torque of 900 bars.
6.Crankpin Cleaning: Clean crankpins and check for abnormal scoring marks.
Turbochargers
1.Cartridge Removal: Remove both turbocharger cartridges.
2.Nozzle Ring Replacement: Remove and replace nozzle rings.
3.TC Cartridge Dismantling: Dismantle TC cartridges for bush and labyrinth seal replacement.
4.Reassembly: Reassemble the cartridges.
5.Clearance Measurement: Measure and record clearances.
6.Charge Air Cooler (CAC) Cleaning: Clean the Charge Air Cooler (CAC) to maintain optimal air intake temperature.
7.CAC Pressure Test: Perform a pressure test on the CAC to detect leaks.
8.Air Intake Filter Cleaning: Clean air intake filter room inertia louvers and replace the oil.
Engine Frame and Bed Plate
1.Holding-Down Bolts: Retighten holding-down bolts to secure the engine to its foundation.
2.Engine-Base Frame Bolts: Retighten bolts between the engine and base frame.
3.Safety Cover Overhaul: Overhaul safety covers.
4.O-ring Change: Change O-rings of camshaft inspection doors and CC doors.
5.Conical (AVM) Bolts: Retighten and measure all conical (AVM) bolts.
Fuel Injection System
1.Valve Inspection and Adjustment: Check fuel injection valves, adjust opening pressure, and change nozzles. Inspect and replace thrust spindles and springs.
2.Fuel Valve O-rings: Change O-rings on all fuel valves.
3.High-Pressure Pipes: Inspect and change fuel high-pressure pipes and O-rings.
4.Pump Height Measurement: Measure and record the nominal height of all fuel injection pumps.
5.Nozzle Cooling Pump Overhaul:
•Replace seals and bearings.
•Replace coupling.
•Overhaul the motor.
Lubricating Oil System
1.Engine-Driven Pump Inspection: Inspect the engine-driven lubricating oil pump and replace bushes.
2.Filter Replacement: Replace all lubricating oil filters.
3.Lube Oil Cooler (LOC) Cleaning: Clean the Lube Oil Cooler (LOC).
4.Centrifugal Filter Maintenance: Clean the centrifugal filter and replace the PRV kit.
5.Pre-Lube Oil Pump Overhaul:
•Overhaul the motor.
•Replace pump seal.
•Replace coupling.
Cooling Water System
1.LT Water Pump Overhaul: Overhaul the LT water pump.
2.Plate Heat Exchanger (PHE) Cleaning: Clean the Plate Heat Exchanger (PHE).
3.Thermostatic Element Check: Check thermostatic elements for 820°C stamping and replace if required.
4.LT Water Thermostat O-ring: Inspect and replace the O-ring of the LT water thermostat.
5.Cooling Water Nipples: Replace cooling water nipples in the exhaust manifold if necessary.
Exhaust System
1.Manifold Cleaning: Clean the complete exhaust manifold and replace intermediate pieces if eroded by cold corrosion.
Compressed Air System
1.Air Starting Motor Overhaul: Overhaul the air starting motor and replace the overhaul kit.
2.Main Air Starting Valve: Overhaul and replace the PRV kit for the main air starting valve.
Alternator
1.Cleaning and Greasing: Clean and replace bearing grease as needed.
Miscellaneous
1.Fuel Pump Index Recording: Record fuel pump index at Governor Index 0.
2.Turning Gear Overhaul:
•Change motor bearings.
•Overhaul mechanical turning gear.
3.Safety Functional Test: Perform a functional test of all safety shutdown switches and analog switches.
Post-Maintenance Procedures and Trial Runs
After completing the scheduled maintenance, a series of post-maintenance procedures are crucial to ensure the engine’s readiness for operation:
1.Trial Runs: Start the engine for trial runs. During this phase, meticulously check and verify the operation of all mechanical and electrical safety devices.
2.Startup Procedures: Follow the MAN B&W standard procedures for all moving parts during startup, ensuring a smooth and safe initiation of engine function.
3.Load Trials: Perform load trials of the engine following the MAN B&W protocol, gradually increasing load to assess performance under various conditions.
4.Data Recording: Record engine performance and measurement data at various loading stages. This data is vital for future reference, troubleshooting, and optimizing operational parameters.
Upon successful completion of the trial runs and satisfactory performance, the engine can be handed over to the customer for normal operation.
Modern Maintenance Considerations and Best Practices
Beyond the scheduled maintenance, several modern considerations and best practices can further enhance the longevity and performance of MAN B&W engines:
•Digitalization and Predictive Maintenance: Leveraging digital tools and sensors for continuous monitoring can enable predictive maintenance, allowing for interventions before failures occur. This approach moves beyond traditional time-based or hour-based maintenance to a more condition-based strategy, optimizing maintenance intervals and reducing unexpected breakdowns.
•Fuel Quality and Lubrication: The type and quality of fuel and lubricating oil significantly impact engine wear and performance. With the increasing use of low-sulphur fuels, proper lubrication strategies are critical to mitigate potential wear on cylinder liners, pistons, and piston rings [2]. Regular analysis of fuel and oil samples can provide early warnings of potential issues.
•Original Spare Parts: Always prioritize the use of original MAN B&W spare parts. Non-genuine parts may compromise engine performance, reliability, and could void warranties [3].
•Certified Technicians: For complex issues, warranty work, or detailed engine diagnostics, engaging certified MAN engine technicians is highly recommended. While basic services can be handled by competent diesel mechanics, specialized knowledge ensures proper diagnosis and repair.
•Continuous Training: Marine engineers and maintenance personnel should undergo continuous training on the latest MAN B&W engine technologies and maintenance protocols. This ensures that the crew is equipped with the necessary skills to handle modern engine systems effectively.
Conclusion
Effective maintenance of MAN B&W engines is a continuous process that combines adherence to scheduled procedures with an understanding of modern engine technologies and best practices. By meticulously following the outlined maintenance steps, incorporating insights from recent advancements, and prioritizing quality components and skilled personnel, operators can ensure their MAN B&W engines deliver optimal performance, reliability, and a long service life. This proactive approach not only safeguards valuable assets but also contributes to safer and more efficient marine operations.
References
[1] Jimmy Rogers. (2025, June 4). MAN Marine Diesel Engine Maintenance Plan- updated June 2025. Retrieved from https://www.jimmyrogersyachtbroker.com/man-marine-diesel-engine-maintenance-plan/
[2] MAN Energy Solutions. MAN B&W two-stroke engines: Service Experience. Retrieved from https://www.man-es.com/docs/default-source/marine/tools/service-experience.pdf?sfvrsn=db3aefdc_18
[3] MAN Energy Solutions. Safety Precautions. Retrieved from https://man-es.com/docs/default-source/service-letters/sl2017-652.pdf?sfvrsn=d6bc892_8
