Project
All cylinder heads were removed and cleaned. Hydraulic loosening was carried out before dismantling. The cylinder heads were pressure tested at 6 bar and no leakage was observed. Dye penetrant testing was also carried out.
The cylinder heads were assembled with new valve seats, valves, valve guides, rotocaps, valve guide O-rings and valve cotters. Valve rotation and rotator operation were checked and found satisfactory. Intake manifolds were cleaned and inspected. The cylinder heads were then mounted and tightened as per OEM procedures, followed by valve clearance adjustment.All piston and connecting rod assemblies were removed and dismantled for inspection and cleaning. Piston crowns were renewed and connecting rod shank bolts were replaced. Piston pins were visually inspected and measured.
Connecting rod small-end bushes were inspected and measured. Crank pins were visually inspected and calibrated for ovality. Big-end ovality measurements were carried out as per OEM instructions, followed by crankpin polishing to remove ridge wear. All connecting rod bearings and piston rings were renewed. Big-end tightening was carried out hydraulically as per OEM procedures.All cylinder liners and water jacket rings were removed and inspected. Deposits and fitting marks were observed in the cooling spaces, following which the water jackets were thoroughly cleaned.
All cylinder liners were renewed along with new O-rings and antipolishing rings. The liners and jacket rings were cleaned and installed as per OEM procedures, with jacket ring screws tightened to the specified torque.The HT and LT water pumps were dismantled, cleaned and inspected. Pitting was observed on selected pump shafts and impellers, resulting in replacement of the affected components.
New pump shafts, impellers, oil seals, mechanical seals, bearings and sealing components were fitted as required for the respective pumps. The HT and LT pumps were installed with new O-rings.The engines were reassembled following the required maintenance procedures. Fuel oil, jacket water and lubricating oil were charged as required for the trial activities. Engine trials were conducted for approximately 2 to 3 hours daily for 5 days and were initially found satisfactory.
At the end of the fifth day, water ingress was observed in the port engine sump. Further checks identified leakage from the port lube oil cooler. The cooler was pressure tested using a fabricated testing arrangement, and deformation of the cooler plates and gasket seating area was observed. Pitting was also noted around the water inlet opening of the cooler end plate, affecting proper O-ring seating.The overhauled engines should be closely monitored during the initial 100 to 150 running hours for abnormal sounds, vibrations and operating parameters. Lube oil filters should be changed after the first 100 hours and inspected for abnormal particles. A lube oil sample should also be taken after the first 100 hours for analysis.
Particular attention should be given to lube oil pressure, jacket cooling water temperature and possible fuel dilution. Engine starting and stopping procedures should follow the maker’s specifications.
For the next overhaul, replacement of the fuel injection pump plunger-barrel assemblies, water line clamps and connection pieces, cam case and crankcase O-rings, and connecting rod small-end bushes should be considered. MAN safety checks and an electrical audit should also be carried out to verify the condition of the electrical and safety systems.Engine trials were conducted for 2 to 3 hours daily over 5 days and were initially found satisfactory. However, water ingress was subsequently observed in the port engine sump due to leakage from the port lube oil cooler.
Final commissioning and load trials were pending at the time of the report. The port lube oil cooler required rectification and leakage confirmation before further trial activities. Port engine lube oil and jacket water charging, jacket pre-heating pump overhaul, automation and safety checks, main air compressor availability, and low-temperature water cooler seawater leakage testing were also identified as pending activities.The port lube oil cooler should be rectified and pressure tested to confirm leak-free operation before final commissioning. The remaining pending systems should also be completed and verified, including the jacket pre-heating pump, engine automation and safety systems, main air compressor and control air system, and low-temperature water cooler.
Close monitoring during the initial post-overhaul operating period will help identify any abnormalities at an early stage and support reliable engine operation.Neptunus completed the major 32K overhaul activities on the port and starboard MAN 8L27/38 Main Engines, covering major engine components, fuel injection systems, lubrication systems, cooling systems, cylinder assemblies, bearings and associated inspections and calibration.
The engines were reassembled as per OEM procedures and trialled for 2 to 3 hours daily over 5 days with satisfactory initial operation. A subsequent water ingress issue in the port engine sump was traced to leakage from the port lube oil cooler. Final commissioning and load trials remained subject to cooler rectification and completion of the identified pending activities.Leave a Reply
