Komatsu 6M108 Marine Engine Parts
The Komatsu 6M108 Marine Engine is associated with six-cylinder Komatsu diesel engines used in marine propulsion and related vessel applications. Marine-market records show 6M108 and 6M108-A1 engines installed in boats, confirming that the designation has been used in marine service. One Japanese used-boat listing, for example, identifies a Komatsu 6M108-A1 rated at 420 PS, while other marine-market examples show different ratings and configurations. This means the exact engine plate should always take priority over a generic 6M108 specification.
This becomes especially important when the engine has already spent many years at sea.
The seawater pump may have been replaced. The turbocharger may have been serviced. Injectors may have been changed. The heat exchanger may have been rebuilt. Even the engine may have undergone one or more major overhauls.
So when someone asks:
“Can you supply parts for a Komatsu 6M108?”
The answer can be yes—but the next question should be:
“What exact 6M108 configuration is installed on the vessel?”
Alfa Marine Spare Parts supports Komatsu 6M108 Marine Engine Spare Parts requirements for:
- Routine Maintenance
- Fuel-System Repairs
- Cooling-System Repairs
- Turbocharger Repairs Where Fitted
- Lubrication-System Repairs
- Cylinder Head Repairs
- Marine Cooling Repairs
- Internal Engine Repairs
- Major Engine Overhauls
Depending on availability, supply options can include genuine Komatsu, OEM-quality, selected aftermarket and remanufactured components.
What Is the Komatsu 6M108 Marine Engine?
The Komatsu 6M108 is a six-cylinder diesel-engine designation encountered in marine applications, including propulsion installations. Marine-market records also identify the related 6M108-A1 designation.
Typical engine and marine systems can include:
- Cylinder Block
- Cylinder Head
- Pistons
- Piston Rings
- Connecting Rods
- Crankshaft
- Main Bearings
- Connecting Rod Bearings
- Camshaft
- Valve Train
- Fuel Injection System
- Air Intake System
- Exhaust System
- Cooling System
- Lubrication System
- Starting System
- Charging System
- Marine Cooling Equipment
- Marine Exhaust Components
Depending on the exact engine configuration, turbocharging equipment may also be installed; multiple marine-market examples describe turbocharged 6M108 engines.
Komatsu 6M108 Technical Information
Unlike some better-documented Komatsu industrial engine families, reliable public factory documentation for the 6M108 marine configuration is limited. For this reason, technical data should be taken from the actual engine identification plate and its corresponding documentation rather than copied from another Komatsu 108-series engine.
Technical InformationKomatsu 6M108ManufacturerKomatsuEngine Model6M108Fuel TypeDieselCylinder ArrangementInline 6-CylinderApplicationMarine / Vessel ApplicationsRelated Marine Designation6M108-A1AspirationConfiguration DependentCooling ArrangementConfirm From Installed Marine EngineRated OutputVaries by VersionRated SpeedVaries by Version
A Japanese marine listing identifies a 6M108-A1 at 420 PS, while other marine-market listings describe 6M108 engines with lower ratings. That variation is exactly why power output should not be generalized across every 6M108.
Why Should the Engine Plate Be Checked Before Ordering 6M108 Parts?
Because 6M108 alone may not tell you enough.
The engine plate can help establish:
- Exact Engine Designation
- Engine Serial Number
- Engine Version
- Rated Power
- Rated Speed
- Original Equipment Configuration
This becomes especially important for:
- Fuel Injection Components
- Turbocharger
- Cooling-Water Pump
- Seawater Pump
- Heat Exchanger
- Starter Motor
- Alternator
- Pistons
- Bearings
- Gasket Sets
- Major Overhaul Components
Is the Komatsu 6M108 the Same as the S6D108?
They should not automatically be treated as the same engine.
The Komatsu 6M108 designation appears specifically in marine-market records, while Komatsu also has other 108-family diesel-engine designations such as S6D108 and SA6D108.
Similar numbers do not prove that the complete engines or their parts are interchangeable.
When requesting components, use:
Komatsu 6M108
or, when applicable,
Komatsu 6M108-A1
exactly as shown on the engine identification plate.
Is the Komatsu 6M108 Turbocharged?
Turbocharged Komatsu 6M108 engines do appear in marine-market examples, so turbocharging is relevant to some 6M108 configurations.
However, the exact arrangement should still be confirmed from the installed engine.
If a turbocharger is fitted, 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
The 6M108 Has Lost Power — Is the Turbocharger Bad?
Not automatically.
Possible causes of reduced engine power can include:
- Restricted Air Filter
- Intake Restriction
- Turbocharger Wear Where Fitted
- Intake-Air Leakage
- Exhaust Restriction
- Restricted Fuel Filters
- Insufficient Fuel Supply
- Injector Problems
- Injection-System Problems
- Low Compression
- Valve Problems
- Excessive Vessel or Propeller Load
A turbocharger should therefore be inspected as part of the complete air, fuel and combustion system.
Why Can a Replacement Turbocharger Fail Again?
Because the turbocharger may have failed as a result of another problem.
Before installing a replacement unit, check areas such as:
- Lubricating-Oil Supply
- Turbocharger Oil Drain
- Engine Oil Condition
- Intake Restriction
- Foreign-Object Damage
- Exhaust Restriction
- Abnormally High Exhaust Temperature
Finding the original cause can prevent damage to the replacement turbocharger.
Komatsu 6M108 Fuel-System Parts
Marine diesel performance depends heavily on clean and consistent fuel delivery.
Potential requirements can include:
- Fuel Injectors
- Injector Components
- Fuel Injection Components
- Fuel Injection Pump Components
- Fuel Transfer Components
- Fuel Filters
- Fuel-Water Separator Elements
- Fuel Pipes
- Fuel Return Components
- Injector Seals
- Gaskets
- O-Rings
Marine repair records also show injector servicing being performed on Komatsu 6M108 engines in vessel applications.
What Are Possible Signs of a 6M108 Fuel-System Problem?
Possible symptoms can include:
- Difficult Starting
- Rough Running
- Uneven Cylinder Operation
- Increased Exhaust Smoke
- Reduced Power
- Poor Response Under Load
- Increased Fuel Consumption
- Abnormal Combustion Noise
But none of those symptoms automatically proves that an injector has failed.
The cause can also involve:
- Fuel Supply
- Compression
- Valve Condition
- Intake Air
- Cylinder Wear
Komatsu 6M108 Fuel Injectors
Potential requirements can include:
- Complete Injectors
- Injector Components
- Injector Seals
- Fuel Pipes
- Fuel Return Components
- 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
- Cylinder Compression
- Intake Valve Condition
- Exhaust Valve Condition
- Valve Adjustment
- Piston Condition
- Piston Ring Condition
- Cylinder Condition
Cylinder-to-cylinder comparison can help determine whether the problem follows the fuel system or the mechanical condition of the engine.
Komatsu 6M108 Air Intake Parts
Potential requirements can include:
- Air Filter Elements
- Air Cleaner Components
- Intake Pipes
- Intake Hoses
- Intake Connections
- Intake Manifold Components
- Clamps
- Gaskets
- Seals
Why Should the Air Intake Be Checked When the 6M108 Produces Black Smoke?
Because black smoke can indicate that the engine is burning fuel without receiving enough combustion air.
Possible causes can include:
- Restricted Air Filter
- Restricted Intake
- Intake Leakage
- Turbocharger Problems Where Fitted
- Fuel Injection Problems
- Injector Problems
- Low Compression
- Excessive Engine Load
The air system should therefore be inspected before expensive fuel-system components are automatically replaced.
Komatsu 6M108 Exhaust-System Parts
Potential requirements can include:
- Exhaust Manifold Components
- Exhaust Connections
- Exhaust Pipes
- Exhaust Gaskets
- Sealing Components
- Fasteners
- Associated Hardware
Where a turbocharger is fitted, the exhaust system also includes the connections that route exhaust energy through the turbine.
What Does Soot Around an Exhaust Joint Mean?
Soot around a manifold or exhaust connection can indicate leakage.
Possible causes include:
- Failed Exhaust Gasket
- Loose Fasteners
- Damaged Flange
- Distorted Sealing Surface
- Cracked Exhaust Component
Cleaning the soot removes the evidence but does not repair the cause.
Komatsu 6M108 Cooling-System Parts
Cooling is particularly important in marine service because the engine is often expected to operate under sustained load.
Potential requirements can include:
- Freshwater Cooling Pump
- Water-Pump Components
- Thermostats
- Thermostat Housing Components
- Cooling Pipes
- Cooling Hoses
- Heat Exchanger Components
- Oil Cooler Components
- Gaskets
- O-Rings
- Seals
Why Can a Komatsu 6M108 Overheat?
Possible causes can include:
- Low Coolant Level
- Poor Coolant Condition
- Thermostat Problems
- Reduced Freshwater-Pump Performance
- Restricted Cooling Passages
- Heat Exchanger Restriction
- Oil Cooler Restriction
- Cooling-System Contamination
- Insufficient Seawater Flow
In a marine engine, both the closed freshwater circuit and raw-water circuit may need investigation.
Why Does the 6M108 Run Hot Only When the Vessel Is Under Load?
This is a useful troubleshooting clue.
At idle or low load, the engine creates less heat.
When the vessel demands more power, the engine produces considerably more heat and the cooling system has to remove it.
A cooling system that has gradually lost capacity may therefore look normal at low load and overheat during harder operation.
Possible areas include:
- Freshwater Pump
- Thermostat
- Internal Cooling Passages
- Heat Exchanger
- Seawater Pump
- Sea Strainer
- Raw-Water Pipework
- Oil Cooler
Komatsu 6M108 Freshwater Pump Parts
Potential requirements can include:
- Complete Water Pump
- Pump Housing
- Pump Shaft
- Bearings
- Mechanical Seal
- Impeller
- Gaskets
- O-Rings
Does a Bad Water Pump Always Leak?
No.
A pump can lose circulation performance without producing a large visible leak.
Possible problems can include:
- Bearing Wear
- Seal Deterioration
- Impeller Damage
- Internal Corrosion
- Cavitation
- Reduced Pumping Efficiency
A water pump should therefore be evaluated as part of the complete cooling system.
Komatsu 6M108 Marine Seawater Pump Parts
Potential requirements can include:
- Complete Seawater Pump
- Pump Housing
- Pump Shaft
- Bearings
- Mechanical Seal
- Impeller Where Applicable
- Wear Components
- Cover Components
- Gaskets
- O-Rings
Are All Komatsu 6M108 Seawater Pumps the Same?
Not necessarily.
Marine installations can vary according to:
- Engine Version
- Marine Conversion
- Vessel Builder
- Cooling-System Design
- Previous Modification
When requesting a seawater pump, provide:
- Pump Manufacturer
- Pump Model
- Existing Pump Number
- Engine Serial Number
- Clear Photographs
- Mounting Arrangement
- Pipe Connections
What Can Cause Low Seawater Flow?
Possible causes can include:
- Restricted Sea Strainer
- Blocked Hull Intake
- Damaged Impeller Where Applicable
- Worn Seawater Pump
- Pump-Shaft Problems
- Restricted Raw-Water Pipework
- Heat Exchanger Restriction
- Debris in the Cooling Circuit
Low seawater flow may become most noticeable when the engine is operating under sustained load.
Komatsu 6M108 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
Why Can a 6M108 Heat Exchanger Gradually Lose Cooling Performance?
Marine heat exchangers operate continuously in an environment where seawater contamination can affect heat transfer.
Possible causes include:
- Salt Deposits
- Scale
- Sediment
- Marine Growth
- Corrosion Products
- Debris
A partially restricted exchanger may still provide enough cooling at low load but struggle as engine output increases.
Komatsu 6M108 Lubrication-System Parts
Potential requirements can include:
- Engine Oil Pump
- Oil Pump Components
- Engine Oil Filters
- Oil Cooler
- Oil Cooler Components
- Oil Pressure Components
- Oil Pipes
- Oil Lines
- Gaskets
- O-Rings
- Crankshaft Seals
Low Oil Pressure — Does the Komatsu 6M108 Need a New Oil Pump?
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
- Internal Engine Wear
- Instrumentation Problems
If bearing clearance is excessive, a replacement oil pump alone will not repair the underlying engine wear.
Komatsu 6M108 Oil Cooler Parts
Potential requirements can include:
- Complete Oil Cooler
- Oil Cooler Core
- Oil Cooler Housing
- Oil Connections
- Cooling Connections
- Gaskets
- O-Rings
- Seals
Oil cooler condition should be considered when investigating unusually high lubricating-oil temperature.
Komatsu 6M108 Cylinder Head Parts
Potential requirements can include:
- Cylinder Head Components
- Cylinder Head Gasket
- Intake Valves
- Exhaust Valves
- Valve Guides
- Valve Seats
- Valve Springs
- Rocker Components
- Valve-Train Components
- Injector Sealing Components
- Valve Cover Gaskets
When Should the 6M108 Cylinder Head Be Inspected?
Cylinder-head inspection may become necessary following:
- Severe Overheating
- Coolant Loss
- Head-Gasket Failure
- Low Compression
- Valve Problems
- Uneven Cylinder Operation
- Abnormal Combustion
- Major Engine Overhaul
What Should Be Checked During Cylinder Head Inspection?
Important areas can include:
- Cracking
- Corrosion
- Flatness
- Sealing Surfaces
- Intake Valves
- Exhaust Valves
- Valve Seats
- Valve Guides
- Valve Springs
- Previous Machining
- Heat Damage
The purpose is to decide what can be reused, what can be reconditioned and what needs replacement.
Komatsu 6M108 Cylinder Head Gasket
If the head gasket has failed, the gasket itself may not be the original problem.
Possible contributing conditions include:
- Engine Overheating
- Cylinder Head Distortion
- Damaged Sealing Surfaces
- Cooling-System Problems
- Incorrect Previous Assembly
Replacing the gasket without correcting the cause can lead to another failure.
Komatsu 6M108 Pistons and Piston Rings
Potential requirements can include:
- Pistons
- Piston Ring Sets
- Piston Pins
- Piston Pin Bushings
- Retaining Components
What Are Possible Signs of Piston, Ring or Cylinder 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 6M108 Only Needs New Rings?
Not necessarily.
Possible causes include:
- Worn Piston Rings
- Cylinder Wear
- Piston Wear
- Ring-Groove Wear
- Internal Engine Damage
New rings cannot compensate for excessive cylinder or piston wear.
The complete condition should be measured and inspected.
Komatsu 6M108 Connecting Rod Parts
Potential requirements can include:
- Connecting Rods
- Connecting Rod Bearings
- Big-End Bearings
- Small-End Bushings
- Connecting Rod Bolts
- Associated Hardware
Connecting rods deserve particular attention following:
- Bearing Failure
- Lubrication Failure
- Piston Damage
- Serious Internal Engine Damage
Komatsu 6M108 Crankshaft and Bearing Parts
Potential requirements can include:
- Crankshaft
- Main Bearings
- Connecting Rod Bearings
- Big-End Bearings
- Thrust Components
- Crankshaft Seals
- Associated Gear Components
Why Should the 6M108 Crankshaft Be Measured Before Ordering Bearings?
Because an older marine engine may already have been overhauled.
Its 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
- Previous Machining
The correct bearing specification should follow the actual crankshaft dimensions.
Measure first. Select bearings second.
Komatsu 6M108 Camshaft and Timing Parts
Potential requirements can include:
- Camshaft
- Camshaft Bearings
- Timing Gears
- Gear-Train Components
- Timing Covers
- Timing Cover Gaskets
- Valve-Train Components
- Related Bushings
These components should be inspected during a major overhaul rather than automatically reused.
Komatsu 6M108 Gaskets and Seals
Potential requirements can include:
- Complete Engine Gasket Set
- Upper Gasket Set
- Lower Gasket Set
- Cylinder Head Gasket
- Valve Cover Gaskets
- Intake Gaskets
- Exhaust Gaskets
- Turbocharger Gaskets Where Applicable
- Oil Cooler Gaskets
- Cooling-System Gaskets
- Injector Seals
- O-Rings
- Crankshaft Seals
The exact gasket package should be matched to the specific 6M108 or 6M108-A1 configuration.
Komatsu 6M108 Starter Motor Parts
Potential requirements can include:
- Complete Starter Motor
- Starter Solenoid
- Starter Components
- Electrical Connections
- Associated Hardware
The 6M108 Cranks Slowly — Does It Need a New Starter?
Not necessarily.
Before replacing the starter motor, investigate:
- Battery Condition
- Battery Voltage
- Battery Cables
- Ground Connections
- Electrical Connections
- Starter Control Circuit
Poor electrical connections can produce symptoms that look very similar to starter-motor failure.
Komatsu 6M108 Alternator Parts
Potential requirements can include:
- Complete Alternator
- Alternator Components
- Drive Belts
- Pulleys
- Belt-Tension Components
- Electrical Connections
For an older vessel, the currently installed alternator should be identified because it may not be the original unit.
Komatsu 6M108 Overhaul Parts
A planned overhaul may require:
- Pistons
- Piston Rings
- Piston Pins
- Main Bearings
- Connecting Rod Bearings
- Thrust Components
- Connecting Rod Bushings
- Cylinder Head Components
- Intake Valves
- Exhaust Valves
- Crankshaft Seals
- Complete Gasket Sets
- Engine Seal Kits
- Fuel-System Components
- Cooling-System Components
- Lubrication-System Components
Depending on the exact configuration and inspection findings, additional requirements can include:
- Crankshaft
- Connecting Rods
- Camshaft
- Fuel Injectors
- Fuel Injection Components
- Turbocharger Where Fitted
- Freshwater Pump
- Seawater Pump
- Heat Exchanger Components
- Oil Pump
- Oil Cooler
- Starter Motor
- Alternator
Should a Complete 6M108 Overhaul Kit Be Ordered Before Disassembly?
Some planned parts can be prepared in advance.
But the final overhaul requirement should ideally follow disassembly, inspection and measurement.
Once the engine is open, the workshop can determine:
Are the cylinders serviceable?
Can the pistons be reused?
Has the crankshaft been machined before?
Which bearing specification is required?
What condition is the cylinder head in?
Are the connecting rods serviceable?
What condition are the cooling-system components in?
A practical overhaul sequence is:
Identify → Disassemble → Clean → Inspect → Measure → Confirm Parts → Rebuild
What Information Should You Send for Komatsu 6M108 Parts?
For accurate Komatsu 6M108 Marine Engine Spare Parts identification, provide:
- Engine Model: Komatsu 6M108
- Exact Variant, Including 6M108-A1 Where Applicable
- Engine Serial Number
- Photograph of Engine Identification Plate
- Existing Komatsu Part Number
- Component Manufacturer Number
- Part Description
- Quantity Required
- Clear Component Photographs
- Vessel Application
- Delivery Country or Nearest Port
For turbochargers, fuel equipment, seawater pumps, heat exchangers, starter motors and alternators, information taken directly from the currently installed component is particularly useful.
Who Do We Supply?
Alfa Marine Spare Parts supports Komatsu 6M108 Marine Engine Spare Parts requirements for:
- Shipyards
- Ship Repairers
- Marine Engineers
- Chief Engineers
- Technical Superintendents
- Fleet Operators
- Marine Service Companies
- Commercial Fishing Companies
- Passenger Vessel Operators
- Workboat Operators
- Offshore Operators
- Government Fleets
- Maritime Contractors
- Boat Builders
- Marine Equipment Distributors
Worldwide Komatsu 6M108 Marine Engine Parts Supply
Alfa Marine Spare Parts supports Komatsu 6M108 requirements for vessel operators, shipyards and marine service companies across Europe, Africa, the Middle East, North America, the Caribbean and other international maritime markets.
Whether the requirement involves injectors, a turbocharger, seawater pump, heat exchanger, cylinder-head components, pistons, bearings or parts for a complete Komatsu 6M108 overhaul, accurate engine identification remains the starting point.