Cummins NT855 Marine Engine Parts
The Cummins NT855 Marine Engine belongs to one of Cummins’ long-established heavy-duty diesel engine families. The NT855 is built around a 14-liter inline six-cylinder platform with an 855 cubic-inch displacement. Cummins lists the NT855 family with an inline six-cylinder configuration and its Pressure Time (PT) fuel system.
For marine engineers, operators and repair companies, the NT855 is a familiar engine because of its heavy-duty mechanical construction and long history in commercial and industrial applications. Cummins has also documented NT855 engines in marine propulsion use.
But when an engine has already spent many years in service, ordering replacement parts by simply saying “Cummins NT855” may not always be enough.
The engine may already have undergone:
- Fuel Injector Replacement
- Fuel Injection System Repairs
- Turbocharger Replacement
- Cylinder Head Reconditioning
- Freshwater Pump Replacement
- Seawater Pump Replacement
- Heat Exchanger Repairs
- Oil Cooler Repairs
- Crankshaft Machining
- Starter Motor Replacement
- Alternator Replacement
- Complete Engine Overhaul
That repair history matters because the component currently installed may not always be the same component originally fitted to the engine.
Alfa Marine Spare Parts supports Cummins NT855 Marine Engine Spare Parts requirements for:
- Routine Maintenance
- Fuel-System Repairs
- Turbocharger Repairs
- Air Intake Repairs
- Exhaust-System Repairs
- Freshwater Cooling Repairs
- Marine Seawater-System Repairs
- Heat Exchanger Repairs
- Lubrication-System Repairs
- Cylinder Head Repairs
- Internal Engine Repairs
- Major Engine Overhauls
Depending on availability, supply options can include:
- Genuine Cummins Parts
- OEM-Quality Components
- Selected Aftermarket Parts
- Remanufactured Components
- Maintenance Parts
- Repair Components
- Overhaul Parts
What Is the Cummins NT855 Marine Engine?
The Cummins NT855 is an inline six-cylinder heavy-duty diesel engine.
Cummins lists the NT855 family at approximately 14 liters displacement, with a 140 mm bore and 152 mm stroke for the N855/855 platform. Cummins also identifies the Pressure Time fuel system as part of this engine family.
Major engine systems can include:
- Cylinder Block
- Cylinder Heads
- Pistons
- Piston Rings
- Piston Pins
- Connecting Rods
- Crankshaft
- Main Bearings
- Connecting Rod Bearings
- Camshaft
- Timing Components
- Fuel System
- Fuel Injectors
- Turbocharger
- Air Intake System
- Exhaust System
- Freshwater Cooling System
- Lubrication System
- Starting System
- Charging System
For marine installations, additional equipment can include:
- Marine Seawater Pump
- Heat Exchanger
- Oil Cooler
- Marine Exhaust Components
- Raw-Water Pipework
- Cooling Hoses
- Vessel-Specific Accessories
Cummins NT855 Technical Information
The exact NT855 specification can vary according to engine configuration and application.
Technical InformationCummins NT855ManufacturerCumminsEngine FamilyNT855Cylinder ArrangementInline 6-CylinderEngine CycleFour-Stroke DieselDisplacementApprox. 14 Liters / 855 in³BoreApprox. 140 mmStrokeApprox. 152 mmFuel SystemPressure Time (PT)FuelDieselCoolingLiquid CooledLubricationPressure Lubrication
Cummins’ NT855 documentation confirms the 14-liter displacement and six-cylinder configuration, while the related N855 technical specification gives the 140 × 152 mm bore-and-stroke dimensions.
The exact aspiration arrangement, rated power, rated speed and marine cooling configuration should be confirmed from the individual engine identification.
What Does NT855 Mean?
The 855 refers to the engine's approximate displacement in cubic inches.
The engine belongs to Cummins’ long-established N/NT855 family.
Different versions and ratings exist within the wider family, so similar 855-series model names should not automatically be assumed to use every component interchangeably.
Is Every Cummins NT855 Engine the Same?
No.
Different NT855 configurations can vary according to:
- Engine Rating
- Application
- Fuel-System Configuration
- Turbocharger Arrangement
- Cooling Arrangement
- Exhaust Equipment
- Marine Conversion
- CPL
- Installed Accessories
- Previous Repairs
This becomes particularly important when ordering expensive components.
Why Is the Cummins Engine Serial Number Important?
The engine model gives you the engine family.
The Engine Serial Number — ESN — helps identify the individual engine more precisely.
For parts identification, useful information includes:
- Engine Model
- Engine Serial Number
- CPL Number Where Available
- Existing Cummins Part Number
- Component Manufacturer Number
- Part Description
- Quantity Required
- Clear Photographs
- Vessel Application
Cummins uses the Engine Serial Number to provide engine-specific parts and technical information, which is why the ESN is particularly useful when identifying replacement components.
Why Is the CPL Number Important on an NT855?
CPL means Control Parts List.
Where available, it can provide additional information about the engine's original configuration.
For a parts inquiry, a strong identification combination is:
Engine Model + Engine Serial Number + CPL + Existing Part Number
This is particularly important for:
- Fuel-System Components
- Turbocharger
- Cooling Pumps
- Cylinder Head Components
- Pistons
- Bearings
- Crankshaft Components
- Starter Motor
- Alternator
What Cummins NT855 Marine Engine Spare Parts Are Available?
Depending on configuration and availability, potential requirements can include everything from normal maintenance components to major internal overhaul parts.
Cummins NT855 Fuel-System Parts
Potential requirements can include:
- Fuel Injectors
- Injector Components
- Fuel Pump Components
- PT Fuel-System Components
- Fuel Transfer Components
- Primary Fuel Filters
- Secondary Fuel Filters
- Fuel-Water Separator Elements
- Fuel Pipes
- Fuel Connections
- Fuel Return Components
- Injector Seals
- O-Rings
- Gaskets
What Is the Cummins NT855 PT Fuel System?
The NT855 family is associated with Cummins’ Pressure Time — PT — fuel system. Cummins lists the Pressure Time fuel system in its NT855 technical specifications.
For parts identification, this means the fuel system should be treated as an important part of the exact engine configuration.
Potential fuel-system requirements can include:
- Fuel Injectors
- PT Fuel Pump Components
- Fuel Supply Components
- Fuel Transfer Components
- Fuel Filters
- Fuel Lines
- Fuel Connections
- Seals
- Gaskets
What Are Signs of a Possible NT855 Fuel-System Problem?
Possible symptoms can include:
- Difficult Starting
- Rough Running
- Uneven Cylinder Operation
- Increased Exhaust Smoke
- Reduced Engine Power
- Poor Response Under Load
- Increased Fuel Consumption
- Abnormal Combustion Noise
However, these symptoms do not automatically confirm a fuel-system failure.
Similar symptoms can also result from:
- Restricted Air Supply
- Turbocharger Problems
- Low Compression
- Valve Problems
- Fuel Contamination
- Restricted Filters
Diagnosis should therefore come before parts replacement.
Cummins NT855 Fuel Injectors
Potential requirements can include:
- Complete Fuel Injectors
- Injector Components
- Injector Seals
- Fuel Connections
- Associated Hardware
One Cylinder Is Running Differently — Should All Six Injectors Be Replaced?
Not automatically.
If one cylinder behaves differently from the other five, investigate that cylinder first.
Possible areas include:
- Injector Performance
- Fuel Delivery
- Compression
- Intake Valve Condition
- Exhaust Valve Condition
- Valve Adjustment
- Piston Condition
- Piston Ring Condition
- Cylinder Condition
Replacing six injectors will not correct a mechanical problem affecting only one cylinder.
Cummins NT855 Turbocharger Parts
Depending on the exact NT855 configuration, potential requirements can include:
- Complete Turbocharger
- Turbocharger Cartridge
- Compressor Components
- Turbine Components
- Bearings
- Seals
- Oil Supply Components
- Oil Drain Components
- Intake Connections
- Exhaust Connections
- Turbocharger Gaskets
- Mounting Components
Cummins documents turbocharged and turbocharged/aftercooled configurations within the 855 family, making exact engine identification important before selecting turbocharger components. (Cummins Inc.)
The Cummins NT855 Has Lost Power — Is the Turbocharger Bad?
Possibly, but not necessarily.
Reduced engine power can also be caused by:
- Restricted Air Filter
- Intake Restriction
- Intake Leakage
- Exhaust Leakage
- Exhaust Restriction
- Restricted Fuel Filters
- Poor Fuel Supply
- Fuel-System Problems
- Injector Problems
- Low Compression
- Valve Problems
- Excessive Vessel or Propeller Load
A replacement turbocharger cannot correct a restricted fuel system or low-compression cylinder.
What Are Possible Signs of an NT855 Turbocharger Problem?
Possible symptoms can include:
- Reduced Engine Power
- Poor Response Under Load
- Black Exhaust Smoke
- Abnormal Turbocharger Noise
- Oil Leakage
- Increased Oil Consumption
- Reduced Boost
- Higher Exhaust Temperature
These symptoms should be evaluated together with the air intake, exhaust, fuel and mechanical systems.
Why Can a Replacement Turbocharger Fail Again?
The failed turbocharger may be the damaged component without being the original cause.
Before installing another turbocharger, investigate:
- Turbocharger Oil Supply
- Turbocharger Oil Drain
- Engine Oil Condition
- Air Intake Restriction
- Foreign-Object Damage
- Exhaust Restriction
- Excessive Exhaust Temperature
Finding the cause helps protect the replacement component.
Cummins NT855 Air Intake Parts
Potential requirements can include:
- Air Filter Elements
- Air Cleaner Components
- Intake Pipes
- Intake Hoses
- Intake Manifold Components
- Clamps
- Connections
- Gaskets
- Seals
Why Can a Restricted Air Filter Make an NT855 Smoke?
A diesel engine needs sufficient clean air for efficient combustion.
If airflow becomes restricted, possible symptoms can include:
- Black Exhaust Smoke
- Reduced Power
- Poor Response Under Load
- Increased Exhaust Temperature
- Increased Fuel Consumption
The air intake should therefore be checked before expensive turbocharger or fuel-system components are replaced.
Cummins NT855 Exhaust-System Parts
Potential requirements can include:
- Exhaust Manifold Components
- Turbocharger Exhaust Connections
- Exhaust Pipes
- Exhaust Gaskets
- Sealing Components
- Fasteners
- Associated Hardware
Why Does an Exhaust Leak Matter on a Turbocharged NT855?
The turbine depends on exhaust-gas energy.
If exhaust escapes before reaching the turbocharger, less energy may be available to drive the turbine.
Possible signs can include:
- Soot Around Exhaust Joints
- Abnormal Exhaust Noise
- Reduced Engine Response
- Reduced Turbocharger Performance
Cummins NT855 Marine Cooling-System Parts
Marine cooling requirements can include:
- Freshwater Pump
- Thermostats
- Thermostat Housing Components
- Marine Seawater Pump
- Heat Exchanger
- Oil Cooler
- Cooling Pipes
- Cooling Hoses
- Gaskets
- O-Rings
- Seals
Why Can a Cummins NT855 Marine Engine Overheat?
Possible causes can include:
- Low Coolant Level
- Poor Coolant Condition
- Thermostat Problems
- Reduced Freshwater-Pump Performance
- Restricted Internal Cooling Passages
- Heat Exchanger Restriction
- Oil Cooler Restriction
- Reduced Seawater Flow
- Blocked Sea Strainer
- Raw-Water-System Restrictions
Marine overheating should be investigated as a complete cooling-system problem rather than automatically blamed on one component.
Why Does the NT855 Overheat Mainly Under Load?
At low load, the engine produces less heat.
When the vessel demands more power, the cooling system must remove considerably more heat.
A system that has lost some of its cooling capacity may therefore appear normal at idle and become hot under sustained load.
Possible areas to investigate include:
- Freshwater Pump
- Thermostats
- Heat Exchanger
- Oil Cooler
- Seawater Pump
- Sea Strainer
- Raw-Water Pipework
- Internal Cooling Passages
Cummins NT855 Freshwater Pump Parts
Potential requirements can include:
- Complete Freshwater Pump
- Pump Housing
- Pump Shaft
- Bearings
- Mechanical Seal
- Impeller
- Gaskets
- O-Rings
Does a Bad NT855 Freshwater Pump Always Leak?
No.
A pump can lose circulation performance without producing a major visible coolant leak.
Possible problems include:
- Bearing Wear
- Seal Deterioration
- Impeller Damage
- Internal Corrosion
- Cavitation
- Reduced Pumping Efficiency
Cummins NT855 Marine Seawater Pump Parts
Depending on the marine installation, potential requirements can include:
- Complete Seawater Pump
- Pump Housing
- Pump Shaft
- Bearings
- Mechanical Seal
- Flexible Impeller Where Applicable
- Wear Components
- Cover Components
- Gaskets
- O-Rings
Are All Cummins NT855 Seawater Pumps the Same?
No such assumption should be made.
Marine cooling equipment may depend on:
- Exact NT855 Configuration
- Engine Serial Number
- CPL
- Vessel Builder
- Marinization Arrangement
- Cooling-System Design
- Previous Replacement
- Previous Modification
When requesting a seawater pump, provide:
- Engine Serial Number
- CPL Where Available
- Pump Manufacturer
- Pump Model
- Existing Pump Number
- Clear Photographs
- Mounting Arrangement
- Pipe Connections
What If the Seawater Pump Impeller Has Missing Blades?
The missing fragments should be located where possible.
They can become trapped in:
- Cooling Hoses
- Pipe Connections
- Heat Exchanger Inlets
- Oil Cooler Passages
- Other Raw-Water Restrictions
Installing a replacement impeller without checking downstream components can leave the cooling system partially restricted.
Cummins NT855 Marine Heat Exchanger Parts
Potential requirements can include:
- Complete Heat Exchanger
- Heat Exchanger Core
- Tube Bundle
- Housing
- End Covers
- Cooling Connections
- Gaskets
- O-Rings
- Seals
What Can Reduce NT855 Heat Exchanger Performance?
Marine heat exchangers can gradually become affected by:
- Salt Deposits
- Scale
- Sediment
- Marine Growth
- Corrosion Products
- Impeller Debris
- Restricted Seawater Flow
A partially restricted exchanger may still cope at light load and become inadequate when the engine is working harder.
Cummins NT855 Oil Cooler Parts
Potential requirements can include:
- Complete Oil Cooler
- Oil Cooler Core
- Oil Cooler Housing
- Oil Connections
- Cooling Connections
- Gaskets
- O-Rings
- Seals
Cummins NT855 Lubrication-System Parts
Potential requirements can include:
- Engine Oil Pump
- Oil Pump Components
- Engine Oil Filters
- Oil Cooler Components
- Oil Pressure Components
- Oil Pipes
- Gaskets
- O-Rings
- Front Crankshaft Seal
- Rear Crankshaft Seal
Does Low Oil Pressure Mean the NT855 Oil Pump Is Bad?
Not automatically.
Possible causes include:
- Low Oil Level
- Incorrect Lubricating Oil
- Deteriorated Oil
- Restricted Oil Filter
- Oil Pump Wear
- Pressure-Regulating Problems
- Excessive Main-Bearing Clearance
- Excessive Connecting Rod Bearing Clearance
- Crankshaft Wear
- Internal Engine Wear
- Instrumentation Problems
If excessive bearing clearance is responsible, replacing only the oil pump will not correct the underlying condition.
Cummins NT855 Cylinder Head Parts
Potential requirements can include:
- Cylinder Head Components
- Cylinder Head Gaskets
- Intake Valves
- Exhaust Valves
- Valve Guides
- Valve Seats
- Valve Springs
- Rocker Components
- Valve-Train Components
- Injector Components
- Valve Cover Gaskets
When Should NT855 Cylinder Head Components Be Inspected?
Inspection may become necessary following:
- Severe Overheating
- Coolant Loss
- Head-Gasket Failure
- Low Compression
- Valve Problems
- Uneven Cylinder Performance
- Abnormal Combustion
- Major Engine Overhaul
Rebuild or Replace NT855 Cylinder Head Components?
The decision should follow inspection.
Important areas can include:
- Cracking
- Corrosion
- Flatness
- Sealing-Surface Condition
- Valve Condition
- Valve Seats
- Valve Guides
- Previous Machining
- Heat Damage
Serviceable components may be suitable for reconditioning, while damaged or dimensionally unsuitable components may require replacement.
Cummins NT855 Pistons and Piston Rings
Potential requirements can include:
- Pistons
- Piston Ring Sets
- Piston Pins
- Piston Pin Components
- Retaining Components
What Are Possible Signs of Piston or Ring Wear?
Possible symptoms include:
- Excessive Blow-By
- Increased Oil Consumption
- Reduced Compression
- Difficult Starting
- Exhaust Smoke
- Reduced Engine Performance
Does Excessive Blow-By Mean the NT855 Only Needs New Rings?
Not necessarily.
Possible causes include:
- Piston Ring Wear
- Cylinder Wear
- Piston Wear
- Ring-Groove Wear
- Internal Engine Damage
New piston rings cannot compensate for excessive cylinder or piston wear.
The complete piston-and-cylinder condition should be inspected and measured.
Cummins NT855 Connecting Rod Parts
Potential requirements can include:
- Connecting Rods
- Connecting Rod Bearings
- Big-End Bearings
- Small-End Components
- Connecting Rod Bolts
- Associated Hardware
Connecting rods should receive careful inspection following bearing failure, lubrication failure or major internal engine damage.
Cummins NT855 Crankshaft and Bearing Parts
Potential requirements can include:
- Complete Crankshaft
- Main Bearings
- Connecting Rod Bearings
- Thrust Components
- Crankshaft Gear Components
- Front Crankshaft Seal
- Rear Crankshaft Seal
Why Should the NT855 Crankshaft Be Measured Before Ordering Bearings?
An older marine engine may already have undergone several overhauls.
The crankshaft may previously have been:
- Polished
- Repaired
- Reground
- Replaced
Inspection should consider:
- Main Journal Diameter
- Connecting Rod Journal Diameter
- Surface Condition
- Scoring
- Taper
- Out-of-Round Condition
- Heat Damage
- Evidence of Previous Machining
If the crankshaft dimensions have changed, the required bearing specification can also change.
Measure first. Select bearings second.
Cummins NT855 Camshaft and Timing Parts
Potential requirements can include:
- Camshaft
- Camshaft Components
- Timing Gears
- Gear-Train Components
- Timing Cover Components
- Timing Cover Gaskets
- Valve-Train Components
- Related Bushings
These components should be inspected during a major overhaul rather than automatically assumed to remain serviceable.
Cummins NT855 Gasket Sets and Seals
Potential requirements can include:
- Complete Engine Gasket Set
- Upper Gasket Components
- Lower Gasket Components
- Cylinder Head Gaskets
- Valve Cover Gaskets
- Intake Gaskets
- Exhaust Gaskets
- Turbocharger Gaskets
- Heat Exchanger Gaskets
- Oil Cooler Gaskets
- Water Pump Gaskets
- Thermostat Gaskets
- Injector Seals
- O-Rings
- Front Crankshaft Seal
- Rear Crankshaft Seal
The gasket package should be matched to the exact Cummins NT855 engine configuration.
Cummins NT855 Starter Motor and Alternator Parts
Potential requirements can include:
- Starter Motor
- Starter Solenoid
- Alternator
- Drive Belts
- Pulleys
- Belt-Tension Components
- Electrical Connections
On an older marine installation, identification from the component currently fitted is particularly useful because electrical equipment may already have been replaced.
Cummins NT855 Overhaul Parts
A planned overhaul can require:
- Pistons
- Piston Rings
- Piston Pins
- Main Bearings
- Connecting Rod Bearings
- Thrust Components
- Cylinder Head Components
- Intake Valves
- Exhaust Valves
- Crankshaft Seals
- Engine Gasket Components
- Engine Seal Components
- Fuel-System Components
- Turbocharger Components
- Cooling-System Components
- Lubrication-System Components
Depending on inspection findings, additional requirements may include:
- Crankshaft
- Connecting Rods
- Camshaft
- Fuel Injectors
- PT Fuel-System Components
- Complete Turbocharger
- Freshwater Pump
- Marine Seawater Pump
- Heat Exchanger Components
- Oil Pump
- Oil Cooler
- Starter Motor
- Alternator
Should a Complete NT855 Overhaul Kit Be Ordered Before Disassembly?
Some planned maintenance and overhaul components can be prepared beforehand.
For a major rebuild, however, the final internal parts requirement should ideally follow inspection and measurement.
Once the engine is opened, the workshop can determine:
What condition are the cylinders in?
Can the pistons be reused?
Has the crankshaft previously been machined?
Which bearing specification is required?
What condition are the cylinder head components in?
Are the connecting rods serviceable?
What condition is the turbocharger in?
A practical overhaul sequence is:
Identify → Disassemble → Clean → Inspect → Measure → Confirm Parts → Rebuild
What Information Should You Send for Cummins NT855 Parts?
For accurate Cummins NT855 Marine Engine Spare Parts identification, provide:
- Engine Model: Cummins NT855
- Exact Engine Variant Where Available
- Engine Serial Number
- CPL Number Where Available
- Photograph of the Engine Identification Plate
- Existing Cummins Part Number
- Component Manufacturer Number
- Part Description
- Quantity Required
- Clear Photographs
- Vessel Application
- Delivery Country or Nearest Port
For turbochargers, PT fuel equipment, freshwater pumps, seawater pumps, heat exchangers, starter motors and alternators, identification from the currently installed component is particularly useful.
Who Do We Supply?
Alfa Marine Spare Parts supports Cummins NT855 Marine Engine Spare Parts requirements for:
- Shipyards
- Ship Repairers
- Marine Engineers
- Chief Engineers
- Technical Superintendents
- Fleet Operators
- Marine Service Companies
- Commercial Fishing Companies
- Offshore Operators
- Government Fleets
- Maritime Contractors
- Boat Builders
- Marine Equipment Distributors
- Commercial Vessel Operators
Worldwide Cummins NT855 Marine Engine Parts Supply
Alfa Marine Spare Parts supports Cummins NT855 requirements for customers across Spain, Italy, Monaco, France, the Netherlands, Belgium, Germany, Greece, the United Kingdom, Dubai and the UAE, Nigeria, Miami and Florida, Texas, Toronto and Canada, the Caribbean, South America and other major international seaports.
Whether the requirement involves fuel injectors, PT fuel-system components, a turbocharger, freshwater pump, seawater pump, heat exchanger, cylinder head components, crankshaft, bearings, gasket components or a complete Cummins NT855 overhaul parts package, accurate engine identification remains the starting point.