6LEL35

Common issues

• Fuel injector nozzle fouling and wear due to HFO operation, leading to poor atomization and increased fuel consumption.
• Exhaust valve burning, seat corrosion, or stem sticking, often exacerbated by high temperatures and HFO combustion byproducts.
• Cylinder liner scuffing or excessive wear, potentially caused by poor lubrication, cold corrosion, or abrasive particles in combustion.
• Piston ring sticking or breakage due to carbon deposits from HFO, leading to blow-by and increased lube oil consumption.
• Turbocharger fouling (turbine and compressor sides) and bearing wear, impacting engine performance and efficiency.
• Main and connecting rod bearing wear, often linked to lube oil contamination, degradation, or insufficient oil film.
• Fuel pump element wear, affecting injection timing and pressure, critical for efficient combustion.
• Excessive engine vibration, potentially indicating misalignment, worn couplings, or combustion imbalance.

Inspection checklist

• Visual inspection for all types of leaks (fuel, lube oil, cooling water, exhaust gas) particularly around high-pressure fuel lines and connections.
• Check all engine gauge readings (lube oil pressure/temp, cooling water pressure/temp, exhaust gas temps per cylinder, charge air pressure/temp) against normal operating parameters and logbooks.
• Listen for abnormal engine sounds (knocking, rattling, hissing) and assess vibration levels throughout the engine and its auxiliaries.
• Inspect the condition of fuel filters, lube oil filters, and air filters; check for signs of clogging or damage.
• Verify the functionality of engine safety devices (overspeed trip, low lube oil pressure shutdown, high cooling water temperature shutdown) through records or functional tests where feasible.
• Inspect the turbocharger for signs of fouling, oil leaks, or excessive axial/radial play (when engine is stopped and cool).
• Check the crankcase breather for excessive blow-by, which can indicate piston ring or liner wear.
• Assess the overall cleanliness and housekeeping of the engine and surrounding engine room, indicating maintenance standards.
• Examine exhaust manifold and piping for cracks, leaks, and proper insulation/lagging.
• Verify proper operation and condition of fuel oil supply and booster pumps, including their filters and heaters for HFO operation.

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Complete fuel injector assemblies or at least nozzles (one set per cylinder).
• Piston rings (complete set for at least one cylinder).
• Main and connecting rod bearings (at least one set of each size).
• Exhaust valve spindles and seats (at least one set per cylinder).
• Fuel pump elements (at least one set per cylinder).
• Various filters (fuel, lube oil, air) for routine replacement.
• Assortment of gaskets and O-rings, especially for cylinder head, fuel lines, and crankcase.
• Turbocharger bearing cartridge or repair kit.

Safety

• High-pressure fuel oil leaks: Extremely dangerous, can ignite spontaneously or create an explosive mist, leading to severe fire and burn hazards. Ensure proper shielding and leak detection.
• Hot surfaces: Exhaust manifold, turbocharger, cylinder heads, and steam/thermal oil lines pose severe burn risks. Ensure proper lagging and warning signs.
• Moving machinery: Exposed rotating parts (flywheel, crankshaft, coupling) present entanglement hazards during operation or improper maintenance.
• Crankcase explosions: Accumulation of oil mist in the crankcase can ignite from hot spots (e.g., worn bearings), leading to violent explosions. Ensure crankcase relief valves are functional and regular oil mist detector checks.
• Exhaust gas leaks: Contains toxic gases (CO, NOx) and can lead to asphyxiation or poisoning in enclosed spaces. Ensure exhaust system integrity.

Class survey

Class surveyors typically focus on the integrity of the engine's structure and its safety systems. Key checks include a thorough review of maintenance records (PMS adherence, logbooks, oil analysis reports), functional testing of all safety devices (overspeed, low lube oil pressure, high temperature shutdowns), and verification of alarm systems. Crankshaft deflection measurements are often required at specific intervals. During major surveys, a specified number of main and connecting rod bearings will be opened for visual inspection and clearance checks. The overall condition of the engine room, including fire safety arrangements, lagging of hot surfaces, and absence of leaks, is also critically assessed. Fuel system integrity, especially high-pressure lines and shielding, is a priority due to fire risk. Turbocharger condition and overhaul records are also reviewed.

Estimated lifetime: 80,000 to 120,000 running hours before requiring a major overhaul (e.g., crankshaft out, full rebuild), assuming diligent maintenance and component replacement.