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Mitsubishi
7UEC33LSE
The Mitsubishi 7UEC33LSE is a low‑speed, two‑stroke marine diesel engine delivering up to 4 340 kW at 200 rpm, designed for large cargo vessels and notable for its proven Japanese engineering and Tier II emissions compliance.
4340.0 kW
Power
Engine Specifications
7
Cylinders
330 mm
Bore
1050 mm
Stroke
4,340 kW
MCR Power
200.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Mitsubishi UEC (LS/LA/LSE/LSII)
· Tier: IMO Tier II
· Fuel: HFO, MDO
Inspector Detail
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Designation decoded
7-Zylinder Mitsubishi UEC 33 cm Bohrung, Long Stroke Eco (LSE) Baureihe. Kompakter Kreuzkopf-Zweitaktmotor mit konventioneller Nockenwellensteuerung, optimiert auf Brennstoffeffizienz. Kleinste Bohrung im UEC-Programm.
Background
The 7UEC33LSE is a compact slow-speed two-stroke engine with 330 mm bore and 1050 mm stroke for smaller merchant vessels such as coastal cargo ships and small tankers. The 7-cylinder configuration provides more even torque delivery than the 6-cylinder variant. As an LSE model, the engine is optimized for low fuel consumption and supports slow-steaming operation.
Calculated metrics
Stroke To Bore Ratio
3.182
Inspector checklist
Zylinderinspektion
- Measure cylinder liner wear – at 330 mm bore, tolerances are tight
- Inspect piston rings for wear and free movement
- Kolbenkrone auf thermische Rissbildung inspizieren
- Auslassschlitze auf Ablagerungen kontrollieren
Triebwerk
- Crosshead bearing clearance to be measured and documented
- Kurbelwellendurchbiegung messen
- Inspect piston rod and gland for wear
- Pleuelschrauben auf vorgeschriebene Vorspannung kontrollieren
Brennstoffsystem
- Einspritzventile auf Prüfstand testen
- Brennstoffpumpen-Zustand beurteilen
- Steuerzeiten gegen Technical File verifizieren
- Check fuel quality and treatment
Exhaust and charging system
- Abgastemperatur-Spreizung zwischen allen 7 Zylindern dokumentieren
- Turbolader-Zustand inspizieren
- Ladeluftkühler auf Verschmutzung prüfen
- Examine exhaust valves for erosion and corrosion
Eco-Betriebsparameter
- Slow-Steaming-Konfiguration mit Herstellervorgaben abgleichen
- Zylinderöl-Feedrate für Teillast optimieren
- Monitor and document SFOC values
- Monitor turbocharger operating point at part load
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust gas temperature per cylinder | 340–420 °C | Abweichungen deuten auf ungleichmäßige Verbrennung hin |
| Pmax-Zylindergleichmäßigkeit | ±3 bar | Deviation requires fuel injection and compression testing |
| Spülluftdruck | 1.2–2.5 bar (lastabhängig) | Niedriger Druck zeigt Auflade-Probleme an |
| Zylinderöl-Feedrate | 0.6–1.1 g/kWh | Deviations affect wear and deposits |
| Kühlwasser-Temperatur | 80–85 °C | Elevated values indicate deposits or gas bypass |
| Spezifischer Brennstoffverbrauch | Gemäß Hersteller-Testbed-Daten | Elevated SFOC indicates wear or misalignment |
Common Failure Modes
Cold corrosion at part load operation
Symptoms: ['Erhöhter Laufbuchsenverschleiß', 'Korrosive Oberflächen im Zylinder', 'Steigende Eisenwerte in Zylinderöl-Analyse']
Causes: Sulfur condensation at low wall temperatures, Unzureichende BN des Zylinderöls, Zu niedrige Kühlwassertemperatur
Preventive: Adjust cylinder oil BN to sulfur content, maintain minimum cooling water temperature, monitor wear closely
Fuel injection valve problems at small bore
Symptoms: ['Ungleichmäßiger Motorlauf', 'Rauchentwicklung', 'Erhöhte Abgastemperatur einzelner Zylinder']
Causes: Kleine Düsenbohrungen verstopfungsanfälliger, Coking during heavy fuel oil operation, Verschlissene Düsennadel
Preventive: Inspect fuel injection valves at shorter intervals, optimize fuel treatment, clean nozzle holes at every service
Turbocharger instability at 7 cylinders
Symptoms: ['Surging at load change', 'Spülluftdruck-Schwankungen', 'Erhöhte Geräuschentwicklung']
Causes: Uneven exhaust pulses at 7 cylinders, Verschmutzte Turbinenblätter, Betrieb unterhalb der Stabilitätsgrenze
Preventive: Turbolader-Reinigung gemäß Intervall durchführen, Abgas-Sammelleitung auf Undichtigkeiten prüfen, Betriebsgrenzen einhalten
Expert tips
- 💡 At 330 mm bore, components are relatively light and can be handled on board without special equipment – this enables more frequent inspections at sea.
- 💡 The 7-cylinder arrangement produces a more irregular ignition interval than the 6-cylinder – monitor torsional vibrations and verify damper condition at every class survey.
- 💡 In eco mode on small engines, pay special attention to adequate component temperatures to prevent cold corrosion.
Related components
Turbocharger and charge air cooler
Nockenwellenantrieb
Fuel injection valves and fuel pumps
Zylinderöl-Dosiersystem
Kolbenkühlöl-Kreislauf
Abgasventil-Drehvorrichtung
Torsionsschwingungsdämpfer
Anlassluftverteiler
Classification & regulatory
MARPOL Annex VI NOx Tier II. In eco mode in ECAs ensure SOx compliance (LSFO/ULSFO or scrubber). Technical File must document all eco-relevant parameters. Small engine class – at class survey pay special attention to correct maintenance documentation. J-ENG (from 2018) to be considered as manufacturer.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 44
5UEC33LSE
5 cyl
· 3,100 kW
5UEC37LA
5 cyl
· 4,250 kW
5UEC43LSE
5 cyl
· 6,000 kW
5UEC45LA
5 cyl
· 7,000 kW
5UEC50LSE
5 cyl
· 9,250 kW
5UEC50LSII
5 cyl
· 9,500 kW
5UEC52LA
5 cyl
· 10,250 kW
5UEC60LS
5 cyl
· 14,500 kW
5UEC60LSII
5 cyl
· 15,250 kW
5UEC68LSE
5 cyl
· 19,500 kW
5UEC68LSII
5 cyl
· 20,250 kW
5UEC85LSII
5 cyl
· 29,000 kW
6UEC33LSE
6 cyl
· 2,100 kW
6UEC37LA
6 cyl
· 5,100 kW
6UEC43LSE
6 cyl
· 7,200 kW
6UEC45LA
6 cyl
· 5,610 kW
6UEC50LSE
6 cyl
· 7,320 kW
6UEC50LSII
6 cyl
· 11,400 kW
6UEC52LA
6 cyl
· 12,300 kW
6UEC60LS
6 cyl
· 17,400 kW
6UEC60LSII
6 cyl
· 18,300 kW
6UEC68LSE
6 cyl
· 23,400 kW
6UEC68LSII
6 cyl
· 24,300 kW
6UEC85LSII
6 cyl
· 22,680 kW
7UEC37LA
7 cyl
· 5,950 kW
7UEC43LSE
7 cyl
· 8,400 kW
7UEC45LA
7 cyl
· 9,800 kW
7UEC50LSE
7 cyl
· 12,950 kW
7UEC50LSII
7 cyl
· 13,300 kW
7UEC52LA
7 cyl
· 14,350 kW
7UEC60LS
7 cyl
· 14,420 kW
7UEC60LSII
7 cyl
· 21,350 kW
7UEC68LSE
7 cyl
· 27,300 kW
7UEC68LSII
7 cyl
· 28,350 kW
7UEC85LSII
7 cyl
· 40,600 kW
8UEC33LSE
8 cyl
· 4,960 kW
8UEC43LSE
8 cyl
· 9,600 kW
8UEC45LA
8 cyl
· 11,200 kW
8UEC50LSE
8 cyl
· 14,800 kW
8UEC50LSII
8 cyl
· 15,200 kW
8UEC52LA
8 cyl
· 16,400 kW
8UEC60LSII
8 cyl
· 24,400 kW
8UEC68LSII
8 cyl
· 32,400 kW
8UEC85LSII
8 cyl
· 46,400 kW
Components & Design
Component data being added…
Technical Data
Bohrung UEC33LSII
330 mm
Hub UEC33LSII
1050 mm
Hub/Bohr-Verhältnis UEC33LSII
3,18
Bohrung UEC37LSII
370 mm
Hub UEC37LSII
1290 mm
Leistung UEC33LSII (6-Zyl.)
1985–3400 kW @ 215/157 min⁻¹ (verifiziert)
SFOC UEC33LSII
179–183 g/kWh (IMO Tier II, Vollast)
Trockengewicht UEC33LSII
52–78 t (5–8 Zyl.)
Trockengewicht UEC37LSII
83–124 t (configuration not verifiable)
Betriebsmodus
Zweitakt-Kreuzkopfmotor, Gleichstromspülung, Abgasturbolader
Steuerung LSII
Nockenwelle (mechanisch betätigt)
Steuerung Eco-Variante
Elektronisch (Solenoidventile, keine Nockenwelle)
Brennstoff
Schweröl (Heavy Fuel Oil)
IMO-Norm
Tier II; Tier III-konform (mit LPSCR)
unified from engine model
True
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Common failures & inspection points
Cold corrosion on cylinder liners due to sulfuric acid condensation at part load — typical for two-stroke diesels; sulfur dioxide from fuel by
Turbocharger wear due to saltwater corrosion — pitting on turbine casing due to seawater feed in exhaust line, pressure drop due to gap enlargement
Piston/cylinder liner wear due to scuffing at insufficient hydrodynamic oil film or poor scavenge air quality — abrasive wear initiat
Black exhaust at part load (turbo-lag phenomenon) — scavenge pressure increases only when turbocharger accelerates; too much fuel → incomplete combustion, r
Zylinderkopf-Wasserdichtung/Kühlung — Risse/undichte Kopfdichtungen ermöglichen Coolant-Eintrag in Kurbelgehäuse (Milchig-braune Ölverfärbung), Korrosion; Restr
Type-general inspection and maintenance points for this equipment category — not model-specific.
Suppliers & Spare Parts
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Equipment Model #38596
· ✓ still in production