Doosan 4L126TI Marine Engine Parts and Specifications
The Doosan 4L126TI marine engine is a compact, turbocharged and intercooled diesel engine developed for commercial marine propulsion. Its combination of high power output, mechanical fuel injection and robust construction makes it suitable for fishing vessels, workboats, passenger vessels and other demanding marine applications.
Despite the model name, the Doosan 4L126TI is not a four-cylinder engine. It is an inline six-cylinder, four-stroke marine diesel engine. The “4L” designation relates to its four-valve cylinder-head configuration.
With a displacement of 11.051 litres, the engine is available with different power ratings based on the vessel’s operating profile. Published ratings range from approximately 450 PS to 545 PS, allowing the engine to be matched to heavy-duty, medium-duty or light-duty marine applications.
Alfa Marine Spare Parts supports vessel owners, marine engineers, shipyards and engine rebuilders searching for Doosan 4L126TI engine parts, replacement components and technical product information.
Doosan 4L126TI Engine Overview
The Doosan 4L126TI was designed to provide more power while maintaining the compact dimensions, durability and serviceability associated with Doosan mechanical marine engines.
Its inline configuration simplifies installation in commercial engine rooms where space and access can be limited. Turbocharging and intercooling increase the amount and density of intake air supplied to the cylinders, enabling the engine to produce more power from its 11-litre displacement.
The mechanical injection system also makes the engine attractive for commercial operators who prefer a relatively straightforward fuel system without the complexity of a fully electronic common-rail installation.
Main engine characteristics
- Inline six-cylinder configuration
- Four-stroke diesel operating cycle
- Four valves per cylinder
- Direct fuel injection
- Mechanical fuel-injection system
- Turbocharged and intercooled
- Freshwater cooling with a marine heat exchanger
- Seawater pump for raw-water circulation
- 24-volt electric starting system
- Compact commercial marine design
- Multiple duty ratings for different vessel applications
Doosan 4L126TI Technical SpecificationsSpecificationDoosan 4L126TIEngine manufacturerDoosan InfracoreEngine model4L126TIEngine configurationInline six-cylinderOperating cycleFour-stroke dieselFuel systemMechanical direct injectionAspirationTurbocharged and intercooledDisplacement11.051 litresBore × stroke123 × 155 mmHeavy-duty output331 kW / 450 PSMedium-duty output364 kW / 495 PSLight-duty output401 kW / 545 PSHeavy-duty speedApproximately 2,000 rpmMedium-duty speedApproximately 2,100 rpmLight-duty speedApproximately 2,200 rpmCooling arrangementFreshwater cooling with heat exchanger and seawater circuitStarting voltage24 VApproximate dimensions1,131 × 904 × 1,153 mm without reduction gearboxPrimary applicationCommercial marine propulsion
Power output, dimensions and installed equipment may vary according to the engine version, gearbox, cooling arrangement and vessel installation. Always confirm specifications using the engine identification plate and applicable Doosan technical documentation.
Doosan 4L126TI Power Ratings
Selecting the correct duty rating is important when installing or replacing a commercial marine engine. The engine must be matched to the vessel’s annual operating hours, average engine load and expected time at full power.
Heavy-duty rating – 450 PS
The heavy-duty version is rated at approximately 331 kW or 450 PS and is intended for vessels operating for long periods under high load.
Typical applications include:
- Fishing trawlers
- Tugboats
- Cargo vessels
- Push boats
- Commercial ferries
- Continuous-duty workboats
Medium-duty rating – 495 PS
The medium-duty version produces approximately 364 kW or 495 PS. It is suitable for vessels that operate regularly but do not remain continuously at maximum load.
Typical applications include:
- Pilot boats
- Escort vessels
- Passenger boats
- Fishing boats
- Coastal service vessels
- Commercial cruising vessels
Light-duty rating – 545 PS
The light-duty version can produce approximately 401 kW or 545 PS. This rating is intended for vessels that use maximum power for shorter periods and operate fewer hours annually.
Typical applications may include:
- Fast patrol craft
- Recreational vessels
- High-speed passenger boats
- Intermittently operated service vessels
An engine should never be selected only by comparing horsepower. Propeller load, gearbox ratio, vessel displacement, hull design, cooling capacity and operating profile must also be considered.
Doosan 4L126TI Marine Engine BenefitsHigh power from a compact engine
The turbocharged and intercooled design enables the 4L126TI to produce up to 545 PS from an 11.051-litre engine. This provides a favourable power-to-size ratio for engine rooms where installation space is restricted.
Mechanical fuel injection
The mechanical fuel-injection system is familiar to many commercial marine engineers. It can simplify diagnostics and repairs compared with electronically controlled systems, particularly in remote operating areas.
Correct injection timing, injector condition and fuel-pump calibration remain essential for maintaining clean combustion and balanced cylinder performance.
Commercial marine construction
The engine was developed for marine propulsion and incorporates components intended to withstand vibration, salt-laden environments and extended operating periods.
Important marine components include:
- Water-cooled exhaust manifold
- Marine turbocharger
- Charge-air cooler
- Heat exchanger
- Seawater pump
- Marine flywheel housing
- Flexible engine mounts
- 24-volt starter motor
- Marine alternator
- Gearbox coupling arrangement
Multiple duty options
The availability of heavy-, medium- and light-duty power ratings allows the engine to be matched more accurately to the vessel’s operating conditions.
Using a light-duty rating in a continuous heavy-load application can cause excessive thermal loading, accelerated wear and shortened component life. Commercial operators should therefore verify the intended duty classification before selecting an engine or replacement unit.
Doosan 4L126TI Marine Applications
The Doosan 4L126TI can be used in a broad range of propulsion installations, including:
- Commercial fishing vessels
- Trawlers and seiners
- Tugboats and push boats
- Pilot and escort vessels
- Coastal cargo vessels
- Workboats and utility craft
- Passenger ferries
- Patrol boats
- Survey vessels
- Marine construction vessels
- Commercial cruising vessels
The final suitability of the engine depends on correct propeller matching, reduction-gear selection, cooling-system capacity and vessel operating profile.
Doosan 4L126TI Engine Parts
Marine engines operating in saltwater environments require regular inspection and timely replacement of worn components. Alfa Marine Spare Parts can assist with enquiries for Doosan 4L126TI marine engine spare parts, subject to identification and availability.
Commonly requested parts include:
Cooling-system parts
- Doosan 4L126TI seawater pump
- Raw-water pump impeller
- Heat exchanger
- Heat-exchanger end covers
- Oil cooler
- Charge-air cooler
- Thermostat
- Coolant circulation pump
- Cooling-system gaskets
- Seals and O-rings
Fuel-system parts
- Doosan 4L126TI fuel injectors
- Injector nozzles
- Fuel-injection pump
- Fuel lift pump
- High-pressure fuel pipes
- Fuel filters
- Fuel-return lines
- Injection-pump repair components
Turbocharger and air-system parts
- Doosan 4L126TI turbocharger
- Turbocharger repair kit
- Turbocharger bearings and seals
- Exhaust manifold
- Charge-air cooler
- Intake manifold
- Air-filter components
- Exhaust gaskets
Cylinder-head and internal engine parts
- Complete cylinder head
- Cylinder-head gasket
- Inlet and exhaust valves
- Valve guides and valve seats
- Valve springs
- Pistons and piston rings
- Cylinder liners
- Connecting rods
- Main bearings
- Connecting-rod bearings
- Crankshaft
- Camshaft
- Timing gears
Lubrication-system parts
- Engine oil pump
- Oil filters
- Oil cooler
- Oil-pressure sender
- Oil pan gaskets
- Lubrication pipes
- Pressure-relief valve components
Electrical parts
- 24 V starter motor
- Charging alternator
- Engine sensors
- Temperature senders
- Oil-pressure switches
- Wiring harnesses
- Engine control panel components
Information Required for a Parts Enquiry
Doosan engine parts should be identified using more than the engine model alone. Production changes and different marine configurations can result in variations between engines carrying similar model descriptions.
For an accurate quotation, provide:
- Complete engine model
- Engine serial number
- Existing part number
- Description of the required component
- Clear photographs of the old part
- Casting or identification numbers
- Vessel application
- Required quantity
- Delivery destination
For pumps, turbochargers, injectors and electrical components, photographs of the identification plate are especially useful.
Doosan 4L126TI Cooling-System Maintenance
The cooling system is one of the most important systems on a turbocharged commercial marine engine. Restricted seawater flow can quickly increase coolant temperature, charge-air temperature and exhaust temperature.
Components to inspect
- Seawater pump and impeller
- Heat-exchanger tube stack
- Charge-air cooler
- Engine coolant pump
- Thermostats
- Seawater strainer
- Exhaust mixing elbow
- Coolant hoses
- Seawater hoses
- End-cover seals and gaskets
A damaged impeller, blocked seawater strainer or fouled heat exchanger can produce similar overheating symptoms. The complete cooling circuit should therefore be inspected before replacing a major component.
Common Doosan 4L126TI ProblemsEngine overheating
Possible causes include:
- Restricted seawater intake
- Blocked seawater strainer
- Worn seawater-pump impeller
- Damaged seawater pump
- Fouled heat exchanger
- Fouled charge-air cooler
- Defective thermostat
- Low coolant level
- Incorrect propeller loading
- Restricted exhaust system
Black exhaust smoke
Black smoke normally indicates insufficient air, excessive fuel or excessive engine load.
Possible causes include:
- Dirty air filter
- Fouled charge-air cooler
- Turbocharger damage
- Worn or carboned injectors
- Incorrect injection timing
- Overloaded propeller
- Restricted exhaust
- Poor-quality fuel
White smoke
White smoke may be associated with incomplete combustion or coolant entering a cylinder.
Possible causes include:
- Low cylinder temperature
- Poor injector spray pattern
- Low compression
- Incorrect injection timing
- Water-contaminated fuel
- Cylinder-head gasket leakage
- Cracked cylinder head
Persistent white smoke should be investigated promptly, particularly when it is accompanied by coolant loss.
Low engine power
A reduction in available power may result from:
- Restricted fuel supply
- Dirty fuel filters
- Injector wear
- Injection-pump problems
- Turbocharger wear
- Charge-air leakage
- Fouled intercooler
- Exhaust restriction
- Low compression
- Incorrect propeller loading
Marine engines should be tested under load because many turbocharger and fuel-delivery problems may not be visible while the engine is idling.
High oil consumption
Possible causes include:
- Worn piston rings
- Worn cylinder liners
- Turbocharger seal leakage
- Excessive crankcase pressure
- Incorrect oil grade
- External oil leakage
- Worn valve guides or seals
A sudden increase in oil consumption should be investigated before the engine is returned to continuous operation.
Doosan 4L126TI Maintenance Considerations
The exact maintenance schedule should follow the engine’s operation and service manual. Maintenance intervals can change according to fuel quality, oil specification, vessel duty and operating environment.
Typical maintenance work includes:
- Checking engine-oil level
- Checking coolant level
- Draining water from the fuel pre-filter
- Inspecting belts and hoses
- Checking for seawater, coolant, oil and fuel leaks
- Replacing engine oil and oil filters
- Replacing fuel filters
- Inspecting the seawater-pump impeller
- Cleaning the heat exchanger
- Cleaning the charge-air cooler
- Inspecting and testing injectors
- Checking valve clearance
- Inspecting the turbocharger
- Checking engine mounts and alignment
- Inspecting the exhaust system
- Monitoring exhaust temperature and oil pressure
Maintenance intervals should not be invented or taken from an unrelated Doosan engine model. Use the schedule for the exact 4L126TI version and duty rating installed in the vessel.
Ordering New, Used or Reconditioned Parts
Depending on the component and availability, parts may be offered in different conditions:
- New genuine parts
- New OEM-quality replacement parts
- Selected aftermarket parts
- Reconditioned components
- Used serviceable components
- Exchange or core-return components
The condition, warranty and scope of supply should be confirmed before ordering. A complete seawater pump, for example, may include different fittings or drive components from a bare replacement pump.
Why Correct Engine Identification Matters
The names Doosan, Daewoo and HD Hyundai Infracore may appear in documentation or listings connected with this engine family because of historical brand and company changes.
When searching for parts, useful model variations can include:
- Doosan 4L126TI
- Doosan 4L126TI marine engine
- Doosan 4L126TI parts
- Doosan Infracore 4L126TI
- Daewoo 4L126TI
- Hyundai Infracore 4L126TI
- 4L126TI marine diesel engine
Nevertheless, the engine serial number and component part number remain the safest basis for identifying replacement parts.
Frequently Asked QuestionsIs the Doosan 4L126TI a four-cylinder engine?
No. The Doosan 4L126TI is an inline six-cylinder marine diesel engine. The “4L” model designation relates to its four-valve design rather than the number of cylinders.
What is the displacement of the Doosan 4L126TI?
The published engine displacement is 11.051 litres, or 11,051 cc.
How much power does the Doosan 4L126TI produce?
Published output depends on the duty rating. The engine is rated at approximately 450 PS for heavy-duty use, 495 PS for medium-duty use and 545 PS for light-duty use.
Is the Doosan 4L126TI turbocharged?
Yes. It uses a turbocharged and intercooled air system to increase the quantity and density of combustion air entering the cylinders.
Does the Doosan 4L126TI use electronic fuel injection?
Published specifications describe a mechanical direct-injection system rather than a modern electronic common-rail system.
Which vessels use the Doosan 4L126TI?
Typical applications include fishing vessels, tugboats, workboats, pilot boats, ferries, coastal cargo vessels, passenger boats and commercial service craft.
Which Doosan 4L126TI parts are commonly replaced?
Frequently requested components include seawater pumps, impellers, injectors, fuel pumps, turbochargers, heat exchangers, thermostats, oil pumps, gaskets, filters, cylinder-head parts, starter motors and alternators.
How do I identify the correct replacement part?
Provide the complete engine model, engine serial number, original part number and clear photographs of the component and its identification plate.
Can a 545 PS engine be used continuously at full load?
The 545 PS version is a light-duty rating and should not automatically be used for continuous full-load commercial service. The correct rating must be selected according to annual operating hours and load profile.
Why is my Doosan 4L126TI overheating?
Common causes include a blocked seawater strainer, damaged seawater-pump impeller, restricted heat exchanger, defective thermostat, low coolant level, fouled charge-air cooler or excessive propeller load.
Request Doosan 4L126TI Marine Engine Parts
For availability and identification support, send Alfa Marine Spare Parts:
- Engine model
- Engine serial number
- Required part number
- Part description
- Photographs
- Quantity
- Delivery destination
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