"> Mitsubishi 7UEC45LA
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Mitsubishi

7UEC45LA

The Mitsubishi 7UEC45LA is a medium‑speed, two‑stroke diesel main engine delivering up to 9 800 kW at 150 rpm, designed for bulk carriers and tankers with a focus on high power density and IMO Tier II emissions compliance.

9800.0 kW
Power

Engine Specifications

7
Cylinders
450 mm
Bore
1350 mm
Stroke
9,800 kW
MCR Power
150.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Mitsubishi UEC (LS/LA/LSE/LSII) · Tier: IMO Tier II · Fuel: HFO, MDO

Inspector Detail ✓ verified

Designation decoded

Mitsubishi 7UEC45LA – 7-Zylinder, 450 mm Bohrung, 1350 mm Hub, Zweitakt-Kreuzkopfmotor, LA-Baureihe (Low-speed Type A), nockenwellengesteuert

Background

The UEC45LA belongs to the LA series of the Mitsubishi UEC engine family and is a proven two-stroke crosshead marine diesel engine for small to medium-sized cargo ships. The LA variant was one of the earlier further developments with improved power density. With 7 cylinders, the engine is subject to typical torsional vibration risks, which can be particularly pronounced with uneven cylinder numbers. The slightly larger bore compared to the 43 offers higher power potential with the same stroke.

Calculated metrics

Stroke To Bore Ratio
3.0

Inspector checklist

Crankshaft and torsion vibration damper
  • Check torsional vibration damper for silicone oil leakage and temperature development
  • Kurbelwellendurchbiegung an allen Lagerstellen messen
  • 7-Zylinder-spezifische Schwingungsproblematik beachten
  • Barred Speed Range-Dokumentation auf Aktualität prüfen
Cylinder unit and combustion
  • Measure liner wear and ovality
  • Check piston rings for end gap and wear profile
  • Control scavenge ports for coking and blockage
  • Inspect cylinder head valve seats and exhaust valves
Camshaft and fuel injection system
  • Measure camshaft drive chain for elongation and wear
  • Check fuel injection pumps for delivery rate and timing
  • Fuel injectors – check opening pressure and spray pattern
  • Kraftstoff-Hochdruckleitungen auf Materialermüdung prüfen
Crosshead and connecting rod
  • Check crosshead bearing clearance and oil supply
  • Pleuelstangenschrauben auf korrekte Vorspannung prüfen
  • Control piston rod stuffing box and scraper rings
  • Examine guide bars for wear pattern and scoring
Lubrication and cooling system
  • Piston cooling oil – flow rate and outlet temperature
  • Hauptlager-Schmierölversorgungsdruck kontrollieren
  • Check cooling water quality and inhibitor concentration
  • Monitor cylinder oil dosage and quality

Logbook reference values

Parameter Expected Deviation means
Maximaler Zünddruck (Pmax) 125–150 bar (lastabhängig) Elevated values indicate excessively early injection timing, low values point to compression losses or nozzle wear
Exhaust gas temperature per cylinder 330–410 °C at rated load Increased spread >30 °C between cylinders requires power balancing; single-cylinder rise indicates nozzle or valve problems
Spülluftdruck im Receiver 1,3–2,2 bar (lastabhängig) Low values signal turbocharger fouling or charge air cooler blockage
Kühlwasser-Austrittstemperatur 78–88 °C Deviations indicate thermostat fault, scale deposits or flow disruptions
Kolbenkühlöl-Temperatur (Austritt) 45–55 °C Rise indicates piston crown overheating or reduced cooling oil quantity
Schmieröldruck vor Motor 2,5–4,0 bar Pressure drop may point to filter fouling, pump wear or bearing damage
Kompressionsdrücke 90–120 bar (lastabhängig) Low compression indicates piston ring wear, valve leakage or liner wear

Common Failure Modes

Auslassventilversagen
Symptoms: ['Erhöhte Abgastemperatur am betroffenen Zylinder', 'Leistungsverlust', 'Abgasverfärbung', 'Abnormale Geräusche am Zylinderkopf']
Causes: Valve seat corrosion due to hot corrosion, Unzureichende Ventildrehvorrichtungsfunktion, Mangelhafte Kraftstoffqualität (hoher Vanadiumgehalt), Thermische Überlastung
Preventive: Valve turning device to be checked regularly for function, valve seats to be reground during overhaul, fuel treatment to be optimized
Torsionsschwingungsschäden
Symptoms: ['Abnormal vibrations at certain speeds', 'Rissbildung am Schwingungsdämpfer', 'Auffällige Geräuschentwicklung am Antriebsende', 'Ungewöhnliche Kurbelwellendurchbiegungswerte']
Causes: Betrieb in gesperrten Drehzahlbereichen, Alterung des Schwingungsdämpfers, 7-cylinder torsional excitation at certain orders, Insufficient damper maintenance
Preventive: Barred Speed Range strikt einhalten, Dämpfer gemäß Herstellerintervall überholen, regelmäßige Schwingungsmessungen durchführen
Fuel injection pump wear
Symptoms: ['Ungleichmäßige Leistungsverteilung', 'Erhöhter Kraftstoffverbrauch', 'Rauchentwicklung', 'Abweichende Zünddrücke']
Causes: Kontaminiertes Kraftstoffsystem, Plunger/barrel wear, Mangelhafte Kraftstoffaufbereitung, Überschrittene Wartungsintervalle
Preventive: Kraftstoffaufbereitung (Separatoren/Filter) optimieren, Einspritzpumpen-Überholungsintervalle einhalten, regelmäßige Leistungsmessungen durchführen

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Related components

Turbolader (Laufrad-Zustand, Lagerverschleiß, Nassreinigungsintervalle) Ladeluftkühler (Reinigungszustand, Zinkprotektoren) Anlassluftsystem (Steuerventile, Verteiler, Kompressoren) Cylinder oil dosing unit and distribution lines Exhaust gas boiler and economizer Kurbelgehäuseölnebelmelder (OMD) Shaft generator and coupling elements

Classification & regulatory

According to IACS UR M68, barred speed range provisions must be documented and observed. Torsional vibration damper overhaul according to classification requirements. Crankshaft deflection to be submitted at intermediate and renewal surveys. NOx Technical File and EIAPP certificate according to MARPOL Annex VI must be current. When replacing cylinder components, conformity with the NOx Technical File must be ensured.

Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.

Components & Design

Component data being added…

Technical Data

Bohrung x Hub UEC45LSE 450 x 1930 mm
Bohrung x Hub UEC50LSE 500 x 2050 mm
BMEP UEC45LSE 22.0 bar (C1-Variante 22.0 bar)
BMEP UEC50LSE 20-21 bar
Mittlere Kolbengeschwindigkeit UEC45LSE 8.5 m/s (Basis für 6-Zyl @ 130 rpm)
Mittlere Kolbengeschwindigkeit UEC50LSE 8.0-8.5 m/s
SFOC UEC45LSE 169 g/kWh (geprüft 2008)
SFOC UEC50LSE-Eco-B1 167 g/kWh (6-Zyl-Basis @ 124 rpm)
Trockengewicht UEC45LSE 195 tonnes (6-cylinder base), 161–243 t depending on configuration
Trockengewicht UEC50LSE 188-405 Tonnen (5-10 Zyl mit Gusseisenbett-Optionen)
Leistung pro Zylinder UEC45LSE 1245 kW (6-Zyl @ 130 rpm)
Hub/Bohrung Verhältnis 4.0-4.29 (LSE-Serie)
Turbolader Mitsubishi MET (High-Efficiency-Typ) mit 2-stufiger Option
Lager Plain bearings with white metal (aluminium or tin base)
Energieeffizienz-Status Höchste Klasse in der Serie (gegenüber UEC52LA-Vorgänger)
IMO Tier-Compliance Tier II/III (Eco-Varianten mit SCR/LP-EGR)
Hubvolumen pro Zylinder UEC45LSE ~302 Liter (450 x 1930 mm)
Hubvolumen pro Zylinder UEC50LSE ~402 Liter (500 x 2050 mm)
unified from engine model True

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Common failures & inspection points

Injector valve wear (wear marks on valve seat/valve disc due to poor cooling or oxidation)

Borescope inspection of exhaust valve seats for scratches/wear, dye penetrant test for cracks, leakage measurements (valve should hold pressure under compressed air for 15 min)

Piston ring wear and liner scratch marks due to lubrication film starvation (especially at part load operation)

Liner surface inspection for scratches/grooves, piston run gemietlich measurement, lubricant flow rate check (wrong parameters for part load operation)

Exhaust gas cooler fouling (oil film + water deposits, particularly in drying disturbances)

Measure pressure drop across cooler, check air temperature after cooler, inspect drainage separator for water accumulation

Plain bearing wear with white metal extrusion due to overload (>10% wear critical)

Tägliche Kurbelgehäuse-Ölprobe auf Weißmetall-Partikel (>0.5 mm mit glatter Oberfläche beidseitig = Überbelastung), Lagerspiel-Kontrolle per Schieblehre

Crankshaft grinding fatigue due to stress concentrations (fatigue fracture rare, but possible at spring transition radii)

Check crankshaft bearing flanges with magnifying glass for cracks; crankshaft deflection measurement via dial gauge (indicator set: <0.1 mm critical)

Type-general inspection and maintenance points for this equipment category — not model-specific.

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Equipment Model #38599 · ✓ still in production