⚓ Working on this equipment?
Ask the AI troubleshooter, log your hours on board and turn them into invoice-ready service reports — for this exact model.
Start free — 14 days →
No credit card required
🔧 35 verified suppliers & service companies for Sulzer in the Maritime Network
Find suppliers →
Sulzer
8RTA52U
The Sulzer 8RTA52U is an eight‑cylinder, low‑speed two‑stroke marine diesel engine delivering about 12.5 MW at 120 rpm; its defining feature is the compact RTA series design that provides high specific power for mid‑size vessels.
12560.0 kW
Power
Engine Specifications
8
Cylinders
520 mm
Bore
2078 mm
Stroke
12,560 kW
MCR Power
120.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Sulzer RTA
· Tier: IMO Tier I
· Fuel: HFO, MDO
Inspector Detail
✓ verified
▸
Designation decoded
Sulzer 8RTA52U – 8-Zylinder, Zweitakt-Kreuzkopfmotor, Bohrung 520 mm, Hub 2078 mm, U-Ausführung (Ultra-Langhub), zahnradgetriebene Nockenwelle
Background
The 8RTA52U belongs to the Sulzer RTA series with conventional gear-driven camshaft. The U variant (Ultra-long stroke) offers an extended stroke for improved thermal efficiency and lower speeds, optimized for direct drive of large propellers. Equipped with Variable Injection Timing (VIT), pulse lubrication and Cylinder Liner Unit (CLU). The 8-cylinder configuration is regarded as the vibration-technically most favorable arrangement with excellent mass balance characteristic.
Calculated metrics
Stroke To Bore Ratio
4.0
Inspector checklist
Camshaft and gear drive
- Inspect gear tooth wear and contact pattern of drive gears
- Monitor camshaft bearings for wear and oil supply
- Measure and document camshaft axial clearance
- Cam profiles to be inspected for pitting and surface damage
VIT-System (Variable Injection Timing)
- Check VIT actuator for function and leakage
- Verify injection control timing at various load stages
- Check governor linkage and connections for play
- VIT-Rückmeldung mit Sollwerten vergleichen
Pulse-Schmiersystem
- Schmierölzuführung je Zylinder auf korrekte Dosierung prüfen
- Inspect lubrication points and quills for blockage
- Öldrücke an den Verteilerstationen messen
- Zeitsteuerung der Schmierimpulse kontrollieren
CLU (Cylinder Liner Unit)
- Measure running gear wear at upper and lower measuring points
- Check cooling water spaces for corrosion and deposits
- Dichtungsringe der Laufbuchse auf Zustand kontrollieren
- Inspect tread profile for cloverleafing or uneven wear
Crosshead and running gear
- Kreuzkopflager-Spiel mit Fühlerlehre messen
- Kreuzkopfbolzen auf Oberflächenrisse prüfen (Rissprüfung)
- Inspect guide surfaces for grooves and wear patterns
- Pleuelschrauben-Vorspannung mittels Ultraschall kontrollieren
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Maximaler Zünddruck (Pmax) | 130–145 bar | Deviation indicates faulty injection control, worn piston rings or valve problems |
| Kompresionsdruck (Pcomp) | 110–125 bar | Too low: worn piston rings or leaking exhaust valves. Too high: deposits in combustion chamber |
| Exhaust gas temperature per cylinder | 340–390 °C at full load | Elevated temperature indicates poor combustion, clogged nozzles or afterburning |
| Kühlwasser-Austrittstemperatur Laufbuchse | 75–85 °C | Excessive temperature may indicate deposits in cooling space or disturbed cooling water flow |
| Zylinderölverbrauch | 0,9–1,3 g/kWh | Increased consumption indicates cylinder liner wear or faulty lubrication setting |
| Spülluftdruck | 2,5–3,2 bar (Volllast) | Low scavenge air pressure reduces power and increases thermal load |
| Einspritzdruck | 350–500 bar | Deviation affects atomization, combustion and emission values |
Common Failure Modes
Nockenwellen-Zahnradverschleiß
Symptoms: ['Unregelmäßige Steuerzeiten', 'Erhöhte Geräuschentwicklung im Steuerungsantrieb', 'Metallpartikel im Schmieröl']
Causes: Unzureichende Schmierung der Zahnflanken, Fehlausrichtung des Antriebsstrangs, Exceeding operating hours without inspection
Preventive: Regular tooth flank inspection according to manufacturer interval, oil analysis for metal particles, alignment check during overhauls
VIT-Aktuatorstörung
Symptoms: ['Fehlende Anpassung der Einspritzsteuerzeit', 'Erhöhter Kraftstoffverbrauch', 'Ungleichmäßige Zylinderdrücke']
Causes: Hydraulikleckage im VIT-Aktuator, Wear in governing linkage, Fehlerhafte Rückmeldung des Positionssensors
Preventive: Function test of VIT system at every port call, check hydraulic tightness regularly
Laufbuchsenverschleiß (Cloverleafing)
Symptoms: ['Increased cylinder oil and lube oil consumption', 'Blow-by-Gase im Spülluftkanal', 'Ungleichmäßige Laufflächenabnutzung']
Causes: Fehlerhafte Pulse-Schmiereinstellung, Betrieb mit hohem Schwefelgehalt ohne Anpassung, Exceeding cylinder liner operating hours
Preventive: Regular cylinder liner measurement, adjust lube oil rate to BN value and sulphur content
Kreuzkopflager-Überhitzung
Symptoms: ['Anstieg der Lagertemperatur', 'Metallpartikel im Schmieröl', 'Knock noise at low speeds']
Causes: Mangelhafte Ölversorgung des Kreuzkopflagers, Fehlausrichtung des Kreuzkopfes, Übermäßiges Lagerspiel
Preventive: Lagerspiel regelmäßig messen, Ölzuführungsbohrungen auf freien Durchfluss prüfen, Ölprobenanalyse
Expert tips
- 💡 For the 8-cylinder RTA configuration, pay particular attention to even cylinder pressure distribution – despite most favourable vibration characteristics, thermal imbalances can occur in ultra-long-stroke designs.
- 💡 VIT setting must always be assessed in relation to turbocharger performance – in U designs with extremely high S/B ratio (4.0), the system responds more sensitively to turbocharger deficiencies.
- 💡 Recalibrate pulse lubrication intervals after each cylinder liner measurement based on current wear rates.
Related components
Turbocharger (bearing and compressor efficiency)
Exhaust valve and valve cage
Piston rings and piston crown
Fuel injection nozzles and pumps
Scavenge air port and scavenge ports
Drehschwingungsdämpfer
Main bearing and main bearing studs
Classification & regulatory
Check IMO MARPOL Annex VI compliance. When operating in ECAs, monitor NOx emission values according to Tier II/III. Observe classification society requirements for camshaft inspection and engine overhaul. Condition-based maintenance (CBM) may be recognized by some classes.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
5RTA48T
5 cyl
· 6,600 kW
5RTA48T-B
5 cyl
· 7,150 kW
5RTA52
5 cyl
· 7,350 kW
5RTA52U
5 cyl
· 7,850 kW
5RTA58T
5 cyl
· 10,150 kW
5RTA58T-B
5 cyl
· 10,800 kW
5RTA62
5 cyl
· 10,100 kW
5RTA62U
5 cyl
· 11,000 kW
5RTA62U-B
5 cyl
· 12,000 kW
5RTA72
5 cyl
· 16,000 kW
5RTA72U
5 cyl
· 17,000 kW
5RTA72U-B
5 cyl
· 18,000 kW
5RTA82T
5 cyl
· 16,600 kW
5RTA84T
5 cyl
· 19,100 kW
5RTA84T-D
5 cyl
· 22,600 kW
6RTA48T
6 cyl
· 7,920 kW
6RTA48T-B
6 cyl
· 7,920 kW
6RTA52
6 cyl
· 8,820 kW
6RTA52U
6 cyl
· 9,420 kW
6RTA58T
6 cyl
· 12,180 kW
6RTA58T-B
6 cyl
· 12,960 kW
6RTA62
6 cyl
· 12,120 kW
6RTA62U
6 cyl
· 13,200 kW
6RTA62U-B
6 cyl
· 14,400 kW
6RTA72
6 cyl
· 19,200 kW
6RTA72U
6 cyl
· 20,400 kW
6RTA72U-B
6 cyl
· 21,600 kW
6RTA82T
6 cyl
· 19,920 kW
6RTA84C
6 cyl
· 22,920 kW
6RTA84T
6 cyl
· 22,920 kW
6RTA84T-D
6 cyl
· 27,120 kW
6RTA96C
6 cyl
· 32,940 kW
6RTA96C-B
6 cyl
· 34,320 kW
7RTA48T
7 cyl
· 9,240 kW
7RTA48T-B
7 cyl
· 10,010 kW
7RTA52
7 cyl
· 10,290 kW
7RTA52U
7 cyl
· 10,990 kW
7RTA58T
7 cyl
· 14,210 kW
7RTA58T-B
7 cyl
· 15,120 kW
7RTA62
7 cyl
· 14,140 kW
7RTA62U
7 cyl
· 15,400 kW
7RTA62U-B
7 cyl
· 16,800 kW
7RTA72
7 cyl
· 22,890 kW
7RTA72U
7 cyl
· 23,800 kW
7RTA72U-B
7 cyl
· 25,200 kW
7RTA82T
7 cyl
· 23,240 kW
7RTA84C
7 cyl
· 26,740 kW
7RTA84T
7 cyl
· 26,740 kW
7RTA84T-D
7 cyl
· 31,640 kW
7RTA96C
7 cyl
· 38,430 kW
Components & Design
Component data being added…
Technical Data
unified from engine model
True
🤖 Ask about this model
One free question — answered like a marine engineer. No account needed.
Suppliers & Spare Parts
Direct links to manufacturer, datasheet, spare-parts portal and dealers — request access below.
📄 Request sourcing links & documents🛠 Manage this equipment in your fleet
Cases, daily reports, timesheets and AI troubleshooting in the OceanSphere Marine app — free for 14 days.
Start free trial →🔎 Suppliers & service for this equipment
Find manufacturers, repair shops and spare-part dealers in the Maritime Network — our global company directory.
Maritime Network →Manuals
-
operating
Sulzer RTA Operating ManualWärtsilä Switzerland (historical Sulzer)
-
maintenance
Sulzer RTA Maintenance ManualWärtsilä Switzerland (historical Sulzer)
-
spare_parts
Sulzer RTA Spare Parts CatalogueWärtsilä Switzerland (historical Sulzer)
Working on this unit?
Log hours, photos and findings into an invoice-ready service report — OceanSphere Marine, 14-day free trial.
Need a service partner for Sulzer?
114,000+ shipyards, suppliers and service companies in the Maritime Network directory.
Equipment Model #38676
· ✓ still in production
Wer liefert dieses Teil? 81 Betriebe im Verzeichnis · 10 aus Herstellerlisten
Chongqing Chuanqing Marine Power Equipment Co., Ltd.
Chongqing, China
FM-Power Serviços e Peças
Rio de Janeiro, Brazil
H. Cegielski – Poznań S.A. (FSA)
Poznań, Poland
MARE Supply & Services
Haarlem, Netherlands
Marine Ecology Equipment OÜ
Tallinn, Estonia
SIMARINA UAB
Klaipeda, Lithuania
Shanghai Huiyang Marine Spares & Repairs Co., Ltd.
Shanghai, China
AHB Service Sp. z o.o.
Gdańsk, Poland
Abrau Marine LLC
Houston, United States
Aramco Green Marine Llc Fz
Saudi Arabia
Armaan Enterprises
India
Weitere aus Hersteller- und Marktplatzverzeichnissen:
Baltic Spares Service Ltd · PolandCOOL DYNAMIC - D. GKOUSKOS · GreeceCSSC Marine Service Co., Ltd. · ChinaEDR Antwerp Shipyard · BelgiumHD Hyundai Marine Solution Americas CO. LTD. · United StatesHyosung Marine Co., Ltd. · South KoreaKloska Technical Marine Sales GmbH / Thomsen & Co. GmbHMSHS Pacific Power Group · United StatesRMS Marine Service Company Ltd · ChinaThames Diesel Injection Parts Ltd · United Kingdom