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MAN Energy Solutions
7L70MC-C8
The MAN 7L70MC-C8 is a high‑power, low‑speed two‑stroke main propulsion engine featuring camshaft‑controlled fuel injection and exhaust valves with built‑in Variable Injection Timing (VIT).
43610.0 kW
Power
Engine Specifications
7
Cylinders
700 mm
Bore
2268 mm
Stroke
43,610 kW
MCR Power
91.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: MAN B&W MC/MC-C
· Tier: Tier II
· Fuel: HFO, VLSFO, MDO
Inspector Detail
✓ verified
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Designation decoded
7 stands for 7 cylinders, L for Long-Stroke, 70 for 700 mm bore, MC-C for the MAN B&W MC Compact series, 8 for Mark 8.
Background
The L70MC-C8 is the Long-Stroke variant of the 70-class bore in the MC/MC-C platform. With a more moderate S/B ratio than the S variant, it suits applications with somewhat higher speeds. Typically used in Panamax bulkers and medium-sized tankers. Mark 8 as the final conventional generation.
Calculated metrics
Stroke To Bore Ratio
3.24
Inspector checklist
Running gear & tribology
- Cylinder liners: S/B ratio 3.24 — more moderate lateral forces than the S variant, but still document wear patterns on the thrust and anti-thrust sides
- Piston ring condition: measure butt clearance and wear height, check chrome layer for chipping
- Piston crown: check for cracks and combustion residue, especially at the ring groove edges
Crosshead & stuffing box
- Crosshead guide: document wear pattern, measure clearance
- Monitor stuffing box drainage, check sealing rings for even wear
- Measure piston rod deflection at every docking
Control & hydraulics
- Check camshaft drive and chain tension
- Exhaust valve hydraulics: check pressure and valve lift
- Fuel injection pumps: verify timing and nozzle opening pressure
Scavenge air & exhaust system
- Scavenge air box inspection for oil and water accumulation
- Air cooler cleaning condition and differential pressure
- Exhaust compensators and ducts for cracks
Sealing systems
- Check cylinder cover gaskets for blow-by
- Exhaust valve seat: check grinding pattern and contact pattern
- Scavenge port edges and liner ports for deposits
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust gas temperature after cylinder | 340-410 °C at MCR | Spread >20 °C → injection/compression problem |
| Scavenge air pressure | 2.8-3.5 bar | Drop indicates turbocharger or cooler problems |
| Pmax | Cylinder balance ±3 bar | Deviation → check injection timing |
| Cooling water temperature | 80-85 °C | Single-cylinder deviation >5 °C → check cooling |
| Lube oil pressure before engine | 3.5-4.5 bar | Pressure drop → check filter or pump |
Common Failure Modes
Cylinder liner wear
Symptoms: Increased wear rate, rough running surface, rising oil consumption
Causes: Insufficient cylinder lubrication, Abrasive particles in the scavenge air duct, Unfavorable piston ring configuration
Preventive: Regularly optimize lubrication point distribution and feed rate, maintain scavenge air filter
Exhaust valve failure
Symptoms: Rising exhaust gas temperature, blow-by at the valve seat
Causes: Hot corrosion from vanadium/sodium, Rotocap defect, Thermal fatigue of the valve spindle
Preventive: Check valve rotation at every start, regularly regrind seat
Turbocharger fouling
Symptoms: Falling charge pressure, rising exhaust gas temperatures across all cylinders
Causes: Insufficient water/dry washing, Poor fuel quality, Extended part-load operation
Preventive: Maintain washing intervals, periodically run higher load during slow steaming
Expert tips
- 💡 The L variant has a more moderate S/B ratio (3.24) than the S70 — this means fewer lateral pressure problems, but higher mean piston speed at the same rpm. Watch thermal loading of the piston crown
- 💡 At the 700 bore, cylinder lubrication via quills is critical — check each quill individually for flow during inspection, blocked quills are common
- 💡 MC-C chain drive: measure not only elongation but also check the guide rails in the chain box for wear
Related components
Turbocharger (bearing clearance and balancing)
Scavenge air cooler (both sides)
Fuel pre-heater and viscosity controller
Crankshaft main bearings (temperature trend)
Classification & regulatory
IMO Tier I compliant. For Tier II, adjustments to the injection system and possibly turbocharger matching are required. VLSFO or scrubber mandatory for ECA operation.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
5L35MC-C8
5 cyl
· 6,450 kW
5L42MC-C8
5 cyl
· 10,100 kW
5L60MC-C8
5 cyl
· 21,000 kW
5L70MC-C8
5 cyl
· 31,150 kW
5L80MC-C8
5 cyl
· 42,000 kW
5S26MC-C8
5 cyl
· 3,700 kW
5S35MC-C8
5 cyl
· 7,650 kW
5S42MC-C8
5 cyl
· 12,950 kW
5S46MC-C8
5 cyl
· 15,500 kW
5S50MC-C8
5 cyl
· 18,650 kW
5S60MC-C8
5 cyl
· 28,250 kW
5S65MC-C8
5 cyl
· 35,000 kW
5S70MC-C8
5 cyl
· 40,400 kW
5S80MC-C8
5 cyl
· 51,000 kW
5S90MC-C8
5 cyl
· 64,350 kW
6K80MC-C8
6 cyl
· 43,500 kW
6K90MC-C6
6 cyl
· 30,780 kW
6K90MC-C8
6 cyl
· 56,700 kW
6K98MC-C8
6 cyl
· 85,020 kW
6L35MC-C8
6 cyl
· 7,740 kW
6L42MC-C8
6 cyl
· 12,120 kW
6L60MC-C8
6 cyl
· 25,200 kW
6L70MC-C8
6 cyl
· 37,380 kW
6L80MC-C8
6 cyl
· 50,400 kW
6S26MC-C8
6 cyl
· 4,440 kW
6S35MC-C8
6 cyl
· 9,180 kW
6S42MC-C8
6 cyl
· 15,540 kW
6S46MC-C8
6 cyl
· 18,600 kW
6S50MC-C8
6 cyl
· 22,380 kW
6S50MC-C8.2
6 cyl
· 9,960 kW
6S60MC-C8
6 cyl
· 33,900 kW
6S65MC-C8
6 cyl
· 42,000 kW
6S65MC-C8.2
6 cyl
· 16,440 kW
6S70MC-C8
6 cyl
· 48,480 kW
6S80MC-C8
6 cyl
· 61,200 kW
6S90MC-C8
6 cyl
· 77,220 kW
7K80MC-C6
7 cyl
· 28,980 kW
7K80MC-C8
7 cyl
· 50,750 kW
7K90MC-C8
7 cyl
· 66,150 kW
7K98MC-C7.1
7 cyl
· 40,040 kW
7K98MC-C8
7 cyl
· 99,190 kW
7L35MC-C8
7 cyl
· 9,030 kW
7L42MC-C8
7 cyl
· 14,140 kW
7L60MC-C8
7 cyl
· 29,400 kW
7L80MC-C8
7 cyl
· 58,800 kW
7S35MC-C8
7 cyl
· 10,710 kW
7S42MC-C8
7 cyl
· 18,130 kW
7S46MC-C8
7 cyl
· 21,700 kW
7S50MC-C8
7 cyl
· 26,110 kW
7S60MC-C8
7 cyl
· 39,550 kW
Components & Design
Component data being added…
Technical Data
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Maritime Network →Manuals
-
operating
MAN B&W MC/MC-C Engine Operating Manual (OM-MC-C)MAN Energy Solutions
-
maintenance
MAN B&W MC/MC-C Maintenance Manual (MM-MC-C)MAN Energy Solutions
-
spare_parts
MAN B&W MC/MC-C Illustrated Parts Catalogue (IPC-MC-C)MAN Energy Solutions
-
project_guide
MAN B&W Project Guide MC/MC-C (PG-MC-C)MAN Energy Solutions
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Equipment Model #38235
· ✓ still in production