Yanmar 6LY3-UTP Marine Inboard Diesel Engine 380hp

Description

Yanmar 6LY3-UTP Marine Inboard Diesel Engine 380HP

The Yanmar 6LY3-UTP Marine Inboard Diesel Engine 380HP is a compact, high-performance six-cylinder propulsion engine designed for powerboats, sportfishing vessels, patrol craft, passenger boats, commercial vessels, and luxury yachts requiring dependable power without excessive engine-room weight.

Rated at 279 kW or 380 metric horsepower at 3,300 rpm, the 6LY3-UTP combines turbocharging, intercooling, electronically controlled direct fuel injection, and a compact inline-six design. Its strong power-to-weight ratio makes it particularly attractive for repower projects where owners want improved acceleration and modern engine control while working within an existing engine compartment.

At Yanmar Marine Experts, available engines are quoted according to their actual condition, transmission configuration, control system, included accessories, inspection status, delivery requirements, and intended vessel application.

Yanmar 6LY3-UTP Engine Overview

The Yanmar 6LY3-UTP is a 5.813-litre, inline six-cylinder marine diesel engine using electronically controlled direct fuel injection.

Its turbocharged and intercooled air system supports strong combustion and responsive power delivery across the operating range. Yanmar lists the engine at 380 metric horsepower at 3,300 rpm, with a dry bobtail weight of approximately 640 kg.

The engine can be paired with suitable marine transmissions, including Yanmar’s KMH61A gearbox in approved configurations. Final gearbox selection should be based on vessel displacement, propeller requirements, duty cycle, shaft arrangement, and desired performance.

Key Features of the Yanmar 6LY3-UTP

380HP High-Performance Output

The Yanmar 6LY3-UTP 380HP marine engine delivers substantial propulsion power from a relatively compact engine package.

This output can support:

• Fast cruising performance
• Strong acceleration
• Twin-engine installations
• Sportfishing applications
• Commercial passenger vessels
• Patrol and utility craft
• Repower projects requiring reduced engine weight

Actual vessel performance depends on hull form, displacement, transmission ratio, propeller selection, vessel loading, and sea conditions.

Inline Six-Cylinder Configuration

The six-cylinder arrangement supports smooth power delivery and balanced operation.

Advantages include:

• Reduced vibration
• Smooth acceleration
• Consistent torque delivery
• Stable operation at cruising speed
• Suitability for single- or twin-engine installations

Correct flexible mounts, engine-bed preparation, shaft alignment, and propeller balancing remain essential to achieving smooth operation in the vessel.

Turbocharged and Intercooled

The turbocharger increases the volume of air entering the engine, while the intercooler reduces the temperature of compressed intake air before combustion.

This combination helps improve:

• Power output
• Combustion efficiency
• Throttle response
• Torque availability
• High-load performance

The turbocharger, intercooler, intake system, cooling circuit, and exhaust arrangement should be inspected and maintained according to the applicable Yanmar service schedule.

Electronically Controlled Direct Injection

Yanmar identifies the 6LY3-UTP as using direct injection with electronically controlled fuel delivery.

Electronic control helps regulate injection according to operating conditions, supporting:

• Responsive acceleration
• Smooth engine operation
• Improved fuel management
• More precise combustion
• Integrated monitoring and alarm functions

The engine-control system, wiring harness, displays, throttle controls, and sensors should be supplied as a complete compatible package whenever possible.

Compact Power-to-Weight Ratio

The engine’s approximately 640 kg dry bobtail weight makes it comparatively compact for its rated output.

This can be advantageous when:

• Replacing a heavier older engine
• Improving vessel balance
• Increasing available horsepower
• Creating more service space
• Reducing structural modifications
• Installing twin engines in a restricted compartment

A lighter engine does not automatically guarantee compatibility. Engine beds, shaft centerline, exhaust routing, cooling capacity, and transmission dimensions must still be checked.

Technical Specifications

The published dimensions include a KMH61A gearbox and high-riser exhaust elbow. Measurements can vary with another transmission or exhaust arrangement, so installation drawings for the exact package should be used before modifying engine beds or ordering components.

Suitable Vessel Applications

The Yanmar 6LY3-UTP marine diesel engine may be suitable for:

• Offshore sportfishing boats
• Express cruisers
• Motor yachts
• Patrol boats
• Passenger vessels
• Crew-transfer boats
• Pilot boats
• Commercial fishing vessels
• Fast workboats
• Utility craft
• Semi-displacement vessels
• Planing hulls
• Twin-engine repower projects

Engine selection should be based on more than horsepower. Vessel displacement, hull resistance, duty cycle, gearbox ratio, propeller diameter, shaft size, engine-room ventilation, cooling capacity, and exhaust backpressure must all be evaluated.

Marine Gearbox Compatibility

Yanmar publishes installation drawings for the 6LY3-UTP with the KMH61A marine gearbox.

The engine may also be paired with other approved transmissions where torque capacity, reduction ratio, rotation, controls, and installation dimensions are compatible.

Before ordering, confirm:

• Gearbox manufacturer
• Gearbox model
• Reduction ratio
• Input torque rating
• Output rotation
• Output-flange dimensions
• Shaft diameter
• Coupling dimensions
• Gearbox cooling requirements
• Trolling-valve requirements
• Control-system compatibility

The gearbox ratio must allow the propeller to absorb the engine’s available power while still permitting the engine to reach its specified loaded rpm range.

Propeller and Shaft Requirements

A high-output engine such as the 6LY3-UTP must be matched with an appropriately engineered driveline.

The installation should verify:

• Propeller-shaft diameter
• Shaft material
• Coupling strength
• Key and keyway condition
• Shaft-bearing condition
• Shaft-seal condition
• Propeller diameter
• Propeller pitch
• Number of blades
• Tip clearance
• Propeller rotation

An existing shaft and propeller should not automatically be reused because they worked with the former engine.

The new engine may produce different torque at a different rated speed, particularly when paired with another gearbox ratio. A propeller specialist should calculate an initial specification and confirm the final result through a documented sea trial.

Electronic Controls and Instrumentation

Yanmar lists both Classic hybrid and fully electronic control options for the 6LY3-UTP.

Depending on the package, the installation may include:

• Electronic throttle control
• Electronic gear-shift control
• Digital engine display
• Engine-control module
• Warning alarms
• Diagnostic functions
• Key-start panel
• Second-station controls
• Extension harnesses
• Flybridge control kit

The exact control system should be confirmed before purchase, especially when replacing an older mechanically controlled engine.

Reusing existing controls may require adapters or replacement components, and compatibility should be verified before installation begins.

Standard Engine Package

Yanmar lists the following items as standard equipment for the 6LY3-UTP:

• 12V, 120A alternator
• L-type exhaust mixing elbow
• Air heater

These items are part of Yanmar’s published standard package, but the components included with an engine offered by Yanmar Marine Experts must still be confirmed in the written quotation.

Optional Accessories

Yanmar lists several factory accessory options for the model, including:

• Fuel-water separator
• High-riser mixing elbow
• Lubricating-oil evacuation pump
• Remote oil-filter arrangement
• Coolant-tank air vent
• Flexible engine mounts
• Second-station flybridge kit
• Key-switch ignition panel
• Extension wiring harnesses
• Alternative control heads
• Trolling-mode kit

Accessory availability may depend on production status, engine serial number, package configuration, and current stock.

Fuel-System Requirements

The engine requires a clean and unrestricted diesel fuel supply.

A professional installation should include:

• Clean fuel tanks
• Correctly sized supply lines
• Correctly sized return lines
• Accessible shutoff valves
• Primary fuel-water separators
• Engine-mounted final filtration
• Proper tank ventilation
• Supported marine-grade hoses
• Suitable priming arrangements

Contaminated fuel, air leaks, undersized lines, or restricted filters can reduce available power and contribute to difficult starting or uneven operation.

For a repower, inspect the tank for:

• Water
• Sediment
• Microbial contamination
• Corrosion
• Deteriorated pickup tubes
• Blocked tank vents

Fuel-system components should be sized for the maximum engine demand, not only for normal cruising load.

Cooling-System Configuration

The Yanmar 6LY3-UTP freshwater-cooled marine engine uses an internal coolant circuit supported by a raw-water heat-exchange system.

The complete cooling package may include:

• Engine heat exchanger
• Raw-water pump
• Charge-air cooler
• Gearbox oil cooler
• Raw-water strainer
• Seacock
• Expansion tank
• Thermostats
• Exhaust-water injection

Before commissioning, confirm:

• Correct coolant mixture
• Adequate raw-water intake size
• Accessible seacock
• Clean strainer
• Properly sized hoses
• Correct clamp installation
• Air removed from the coolant circuit
• Strong raw-water discharge
• No coolant or seawater leaks

Routine maintenance should include heat-exchanger inspection, raw-water-pump servicing, cooler cleaning, coolant replacement, hose inspection, and anode replacement where applicable.

Exhaust-System Requirements

The exhaust system must remain within the maximum allowable backpressure for the engine.

The installation should evaluate:

• Exhaust outlet diameter
• Mixing-elbow configuration
• High-riser requirements
• Hose diameter
• Waterlock capacity
• Gooseneck height
• Anti-siphon protection
• Transom outlet position
• Hose support
• Water-ingestion risk

Yanmar provides an L-type mixing elbow as standard and lists a high-riser version as an optional replacement.

The correct choice depends on vessel waterline, engine position, exhaust routing, and available vertical clearance.

An incorrectly designed wet exhaust can create excessive backpressure or allow seawater to enter the engine.

Engine-Room Ventilation

The engine room must supply enough fresh air for combustion while also removing heat produced by the engine, turbocharger, exhaust, alternator, and gearbox.

The installation should check:

• Intake-vent area
• Air-duct size
• Powered blowers
• Hot-air discharge
• Saltwater protection
• Sound-insulation restrictions
• Recirculation of hot air
• Service access around the engine

Ventilation should be assessed under maximum operating load rather than only while the engine is idling at the dock.

Installation Considerations

Before purchasing a Yanmar 6LY3-UTP replacement engine, confirm:

• Access route into the vessel
• Engine-room dimensions
• Engine-bed spacing
• Mounting-center dimensions
• Foundation strength
• Gearbox-output centerline
• Shaft angle
• Coupling dimensions
• Exhaust-elbow clearance
• Cooling-system capacity
• Fuel-system capacity
• Battery configuration
• Control-system compatibility
• Routine maintenance access

The exact Yanmar installation drawing should be used for final measurements because dimensions can vary with the gearbox and exhaust configuration.

Engine Condition and Inspection

Depending on availability, the engine may be supplied as:

• New
• New old stock
• Dealer surplus
• Low-hour used
• Running take-out
• Workshop inspected
• Reconditioned
• Fully rebuilt

The quotation should clearly state the engine condition.

Inspection may include:

• Model and serial-number verification
• External condition assessment
• Starting and running test
• Oil-pressure observation
• Cooling-system inspection
• Electronic diagnostic review
• Fuel-system inspection
• Turbocharger inspection
• Leak check
• Exhaust-smoke assessment
• Alternator test
• Control-system test
• Gearbox engagement test

A rebuilt or reconditioned engine should include a clear description of the work completed and the major components renewed.

Package Contents

Depending on the available unit, a Yanmar 6LY3-UTP package may include:

• 6LY3-UTP base engine
• Marine gearbox
• Electronic engine-control system
• Instrument display
• Throttle and shift controls
• Wiring harnesses
• Starter motor
• Alternator
• Heat exchanger
• Charge-air cooler
• Raw-water pump
• Exhaust mixing elbow
• Flexible engine mounts
• Fuel filters
• Operator documentation
• Installation drawings

Buyers should rely on the written quotation rather than assuming that every factory accessory is included.

Routine Maintenance

Scheduled maintenance may include:

• Engine-oil replacement
• Oil-filter replacement
• Primary fuel-filter service
• Engine fuel-filter replacement
• Water-separator drainage
• Raw-water impeller inspection
• Coolant replacement
• Heat-exchanger cleaning
• Intercooler inspection
• Turbocharger inspection
• Drive-belt inspection
• Valve-clearance checks
• Air-intake inspection
• Anode replacement
• Gearbox-fluid service
• Shaft-alignment inspection
• Electronic fault-code review

Maintenance intervals should follow the official Yanmar operation manual for the engine and the actual vessel duty cycle.

Why Buy From Yanmar Marine Experts?

At Yanmar Marine Experts, we help customers evaluate the complete propulsion package instead of choosing an engine from horsepower alone.

Before preparing a quotation, we can review:

• Vessel make and model
• Vessel dimensions
• Hull type
• Existing engine
• Existing gearbox
• Desired cruising speed
• Duty cycle
• Shaft and propeller arrangement
• Control-system requirements
• Delivery destination
• Installation timeline

Our quotation can clearly identify:

• Engine condition
• Rated output
• Gearbox model and ratio
• Included accessories
• Excluded components
• Inspection status
• Lead time
• Packing method
• Shipping options
• Warranty terms

Worldwide Shipping

Yanmar Marine Experts can arrange domestic and international delivery according to the engine location and customer destination.

Available logistics may include:

• Sea freight
• Container shipping
• Port-to-port delivery
• Door-to-port delivery
• Door-to-door delivery
• Professional export packing

The final shipping quotation depends on engine configuration, gearbox inclusion, packing dimensions, collection location, destination, and delivery terms.

Warranty

Warranty coverage depends on the engine condition and the final sales agreement.

New, surplus, used, inspected, reconditioned, and rebuilt engines may each carry different warranty terms.

Before purchase, review:

• Warranty duration
• Covered components
• Installation requirements
• Commissioning requirements
• Maintenance obligations
• Operating limitations
• Claim procedures
• Exclusions

Request a Quote for the Yanmar 6LY3-UTP

Contact Yanmar Marine Experts for current availability of the Yanmar 6LY3-UTP Marine Inboard Diesel Engine 380HP.

For an accurate quotation, provide:

• Vessel make and model
• Vessel length
• Vessel displacement
• Hull type
• Existing engine
• Existing gearbox and ratio
• Required engine quantity
• Preferred control system
• Required accessories
• Delivery city and country
• Planned installation date

We will confirm the available engine, condition, gearbox options, package contents, price, lead time, packing, shipping, and warranty.

Frequently Asked Questions

How much power does the Yanmar 6LY3-UTP produce?

The engine is rated at 279 kW or 380 metric horsepower at 3,300 rpm.

What is the displacement of the Yanmar 6LY3-UTP?

The engine has a displacement of 5.813 litres, with a bore and stroke of 106 mm × 110 mm.

Is the Yanmar 6LY3-UTP electronically controlled?

Yes. Yanmar lists the engine as using electronically controlled direct fuel injection, with Classic hybrid and fully electronic control options.

Is the Yanmar 6LY3-UTP turbocharged?

Yes. It is turbocharged and intercooled.

What alternator is standard?

Yanmar lists a 12V, 120A alternator as standard, with a 24V, 35A option.

How much does the engine weigh?

The published dry weight without a gearbox is approximately 640 kg or 1,411 lb.

What gearbox can be used with the engine?

Yanmar publishes package drawings for the 6LY3-UTP with a KMH61A transmission. Other suitable marine gearboxes may be possible where torque, ratio, rotation, controls, and dimensions are verified.

Are engine mounts included?

Flexible mounts are listed by Yanmar as optional accessories. Whether they are included with an available engine must be confirmed in the quotation.

Can it replace another 380HP engine directly?

Not automatically. Engine beds, gearbox ratio, shaft diameter, propeller, cooling, exhaust, ventilation, controls, and electrical systems must all be checked.

Do you offer international delivery?

Yes. Yanmar Marine Experts can arrange export packing and international shipping according to the engine location and destination.