NEW Cummins Onan Marine QD 27MDKDU-8253A 27kW Diesel Generator for Sale

The Cummins Onan Marine QD 27MDKDU-8253A is a professional-grade 27kW marine diesel generator engineered to provide dependable 50 Hz electrical power for yachts, commercial boats, passenger vessels, workboats, sportfishing vessels, and other demanding marine applications.

Part of the proven Cummins Onan Quiet Diesel range, the 27MDKDU combines a durable four-cylinder diesel engine, a brushless marine alternator, electronic frequency control, digital generator protection, freshwater cooling, and vibration-reduction technology in one integrated onboard power system.

The generator operates at 1,500 rpm, allowing its four-pole alternator to produce 50 Hz electricity at a lower engine speed than many compact high-speed generator sets. This configuration supports smooth operation, long-term durability, controlled sound levels, and dependable performance during extended marine use.

With a rated output of 27kW, the generator can support substantial onboard electrical loads when correctly sized for the vessel. These may include marine air-conditioning systems, refrigeration, navigation equipment, battery chargers, pumps, lighting, communication systems, entertainment equipment, water makers, galley appliances, and other hotel loads.

The 27MDKDU-8253A is suitable for new vessel construction, generator-room upgrades, and marine generator replacement projects. However, its complete specification number is important. Buyers should verify the exact voltage, phase, amperage, starting voltage, enclosure, cooling arrangement, and supplied accessories associated with the 8253A configuration before ordering.

Cummins offers Onan marine generators across a broad power range, with the company positioning the range for recreational and demanding onboard marine use. The 27MDKDU belongs to Cummins’ 22.5kW, 27kW, and 29kW Quiet Diesel generator family.

Key Features at a Glance

• 27kW marine diesel generator
• Genuine Cummins Onan Quiet Diesel model
• Model and specification: 27MDKDU-8253A
• Designed for 50 Hz marine electrical systems
• Rated operating speed of 1,500 rpm
• Four-cylinder V3300 diesel engine
• Four-stroke, water-cooled engine design
• Brushless four-pole marine alternator
• Electronic frequency control
• Integral voltage regulation
• Advanced digital generator control
• Self-monitoring and diagnostic protection
• Freshwater cooling with marine heat exchanger
• Gear-driven raw-water pump
• Water-cooled exhaust mixing elbow
• Vibration-isolated mounting system
• Optional sound-shield configuration
• Remote monitoring options
• Suitable for recreational and commercial vessels
• Appropriate for new installations and repower projects
• Supported by the Cummins service network

Designed for Demanding Marine Applications

The Cummins Onan 27MDKDU-8253A marine generator is designed for vessels that require reliable onboard AC electricity while cruising, working offshore, operating at anchor, or remaining away from shore power for extended periods.

Suitable applications may include:

• Motor yachts
• Luxury yachts
• Sportfishing boats
• Charter vessels
• Passenger craft
• Commercial workboats
• Patrol boats
• Crew-transfer vessels
• Research vessels
• Expedition yachts
• Offshore-support vessels
• Liveaboard boats
• Custom vessel projects
• Commercial fleet applications
• Marine generator replacement projects
• Vessel electrical-system upgrades

The generator is particularly relevant to vessels using 50 Hz electrical distribution. A qualified marine electrician should confirm that the 8253A specification matches the vessel’s voltage, phase, grounding arrangement, circuit-protection requirements, and connected equipment.

A properly sized 27kW marine generator can support several onboard systems simultaneously. The generator’s actual usable capacity will depend on the combined continuous demand, motor-starting current, air-conditioning compressor loads, battery-charger demand, power factor, and required reserve capacity.

Cummins Onan Quiet Diesel Technology

The Cummins Onan Quiet Diesel platform is developed to provide onboard power while managing the sound and vibration normally associated with diesel generator operation.

An optimized mounting arrangement helps isolate engine and alternator vibration from the vessel. This reduces the transfer of mechanical vibration into decks, cabins, bulkheads, and living spaces.

Quiet Diesel engineering may include:

• Vibration-isolated mounting
• Balanced rotating components
• Controlled low-speed operation
• Air-intake noise reduction
• Electronic governing
• Water-cooled exhaust
• Optional sound-shield enclosure
• Integrated engine and alternator design

When equipped with the appropriate sound shield, Cummins documentation for the 27MDKDU family identifies a published sound level of approximately 65 dB(A) at one metre under the manufacturer’s stated test conditions. Actual onboard sound will depend on the machinery-space layout, ventilation, exhaust installation, insulation, operating load, hull construction, and measurement location.

This makes the generator attractive for yachts, passenger vessels, charter boats, and liveaboard applications where onboard comfort is an important consideration.

Four-Cylinder V3300 Diesel Engine

The Cummins Onan Marine QD 27MDKDU is powered by a V3300 four-cylinder diesel engine.

The engine uses a four-stroke, water-cooled design and operates at 1,500 rpm in the 50 Hz MDKDU configuration. Published Cummins documentation identifies a displacement of approximately 3.318 litres, with a 98 mm bore and 110 mm stroke.

Important engine characteristics include:

• Four-cylinder configuration
• Four-stroke diesel operation
• Water-cooled construction
• Approximately 3.318-litre displacement
• 98 mm cylinder bore
• 110 mm piston stroke
• Rated operation at 1,500 rpm
• Full-flow lubricating-oil filtration
• Marine heat-exchanger cooling
• Electric starting
• Automatic preheating support
• Electronic operating control

The low engine speed is an important benefit for vessels requiring extended generator operation. Rather than relying on a higher-speed engine to produce 50 Hz power, the generator combines a 1,500 rpm diesel engine with a four-pole alternator.

This arrangement supports smooth power production, reduced mechanical stress, controlled operating sound, and dependable marine service.

Stable Electrical Power for Modern Vessels

Modern vessels depend on sensitive electrical and electronic equipment. Navigation displays, communication systems, digital appliances, chargers, computers, automated controls, and entertainment equipment can be affected by unstable voltage or frequency.

The Cummins Onan 27MDKDU addresses these demands through:

• Electronic frequency control
• Digital generator governing
• Integral voltage regulation
• Brushless alternator construction
• Four-pole alternator design
• Rotating-field architecture
• Protected electrical components
• Main AC circuit protection

Cummins identifies electronic frequency control as an important feature for equipment such as digital appliances and computers that require dependable power quality.

The brushless alternator design eliminates routine alternator-brush replacement and supports dependable long-term operation. The alternator and engine are engineered as an integrated generator system rather than as unrelated components assembled around a general-purpose engine.

The exact output voltage, phase, full-load amperage, and winding arrangement of specification 8253A must be verified from the generator nameplate or official build sheet.

Advanced Digital Generator Control

The 27MDKDU uses an advanced digital control system to manage starting, operating conditions, electrical output, shutdown protection, and fault diagnostics.

Depending on the installed equipment, information may be viewed through:

• The local generator control panel
• A remote start-and-stop panel
• An optional Cummins Onan Digital Display
• A compatible vessel-monitoring system

Available operating information may include:

• AC output voltage
• AC frequency
• Generator operating hours
• Engine speed
• Starting-battery voltage
• Engine coolant temperature
• Lubricating-oil pressure
• Generator load
• Pre-alarm information
• Shutdown-fault information
• Service notifications

Optional communication arrangements may allow generator information to be shared with compatible vessel-monitoring systems. Depending on the generator configuration, supported interfaces may include SAE J1939, SmartCraft, or NMEA 2000.

These monitoring capabilities help owners and operators identify developing issues, review generator performance, and understand the reason for a protective shutdown.

Generator Protection and Diagnostics

Marine generators operate in enclosed environments where cooling, lubrication, exhaust flow, and electrical loading must remain within safe operating limits.

Depending on the exact configuration, the Cummins Onan control system may monitor or protect against:

• High engine-coolant temperature
• Low lubricating-oil pressure
• High exhaust temperature
• Loss of raw-water flow
• Low coolant level when the appropriate sensor is installed
• Engine overspeed
• Starter overcrank
• Abnormal output voltage
• Abnormal frequency
• Controller faults
• Sensor faults
• External emergency shutdown inputs

The generator also incorporates AC circuit protection intended to protect the generator output and connected conductors against specified overload or fault conditions.

When the generator shuts down, the fault should be diagnosed and corrected before operation resumes. Repeatedly resetting a protective shutdown without identifying its cause may result in further damage.

Freshwater Cooling With Marine Heat Exchanger

The Cummins Onan 27MDKDU-8253A uses a closed freshwater cooling circuit combined with a marine heat exchanger.

Engine coolant circulates through the diesel engine and carries heat to the heat exchanger. Raw water drawn from outside the vessel passes through the heat exchanger and removes heat from the closed coolant circuit.

This design prevents seawater from circulating directly through the engine’s internal freshwater cooling passages.

The cooling system may include:

• Closed engine-coolant circuit
• Marine heat exchanger
• Expansion tank
• Coolant-recovery bottle
• Thermostat-controlled circulation
• Gear-driven raw-water pump
• Raw-water-flow monitoring
• Water-cooled exhaust mixing elbow

Cummins documentation for the 27MDKDU family lists a cooling-system capacity of approximately 14 litres, although the current documentation for the exact generator should be consulted before servicing or filling the cooling system.

Correct raw-water supply is essential. The vessel should have a properly sized seacock, marine strainer, hoses, clamps, siphon protection, and exhaust arrangement.

Water-Cooled Marine Exhaust

The standard marine arrangement uses a water-cooled exhaust mixing elbow.

Raw cooling water is introduced into the exhaust flow downstream from the engine. This reduces exhaust temperature before the exhaust and water mixture passes through the vessel’s approved wet-exhaust system.

A complete marine exhaust installation may require:

• Water-cooled mixing elbow
• Approved wet-exhaust hose
• Waterlift muffler
• Exhaust water separator
• Siphon-break assembly
• Correct exhaust rise
• Suitable overboard outlet
• Approved clamps and supports
• Adequate machinery-space ventilation

The exhaust system must be designed to prevent seawater from flowing back toward the engine. Incorrect exhaust geometry can cause serious engine damage, particularly when the generator is installed near or below the vessel’s waterline.

A qualified marine installer should determine the correct exhaust components and routing for the vessel.

Performance and Fuel Consumption

The Cummins Onan 27MDKDU is designed to match diesel consumption to the electrical load placed on the generator.

Published Cummins documentation for the 27MDKDU identifies approximate fuel-consumption figures of:

• No load: approximately 1.9 litres per hour
• Half load: approximately 4.5 litres per hour
• Full load: approximately 9.1 litres per hour

These values are manufacturer reference figures. Actual fuel consumption will vary according to electrical demand, generator condition, fuel quality, maintenance, ambient temperature, installation, altitude, exhaust restriction, and other operating factors.

Correct generator sizing is important. A unit that is too small may be overloaded, while an excessively oversized generator may spend long periods operating under an unnecessarily light load.

A complete load analysis should consider:

• Continuous electrical demand
• Intermittent equipment
• Air-conditioning compressors
• Pump and motor starting current
• Refrigeration startup loads
• Battery-charger demand
• Galley appliances
• Water makers
• Lighting and entertainment equipment
• Navigation and communication systems
• Future electrical upgrades
• Required reserve capacity

Performance Benefits

The Cummins Onan 27MDKDU-8253A offers several operational benefits for recreational and commercial vessel owners:

• Reliable 27kW onboard electrical output
• Stable 50 Hz power
• Low-speed 1,500 rpm diesel operation
• Controlled voltage and frequency
• Support for sensitive marine electronics
• Reduced vibration transfer
• Lower machinery noise with the appropriate enclosure
• Efficient freshwater cooling
• Digital generator protection
• Remote monitoring capability
• Brushless alternator reliability
• Practical maintenance access
• Worldwide manufacturer support

These qualities make the generator suitable for vessels that depend on consistent power for comfort, navigation, communication, safety systems, and commercial operation.

Included Equipment

The exact equipment supplied with the 27MDKDU-8253A should be confirmed from the factory build sheet and seller’s quotation.

Typical equipment within this generator family may include:

• V3300 four-cylinder diesel engine
• Brushless four-pole Onan alternator
• Digital generator controller
• Electronic governor
• Integral voltage regulator
• Electric starter
• Automatic preheat system
• Electric fuel-transfer pump
• Engine fuel filter
• Full-flow lubricating-oil filter
• Freshwater cooling system
• Marine heat exchanger
• Raw-water pump
• Coolant expansion and recovery system
• Water-cooled exhaust mixing elbow
• AC main circuit breaker
• Generator running-time meter
• Vibration-isolated mounting
• Oil-drain extension
• Fluid-containment base
• Remote-control connection
• Lifting provision
• Operation and installation documentation

Equipment can vary according to the generator’s build date, electrical configuration, ordered accessories, regulatory certification, and regional specification.

Optional Equipment

Available optional equipment may include:

• Cummins Onan Digital Display
• Remote start-and-stop panel
• Additional remote station
• Remote wiring harness
• NMEA 2000 communication interface
• SAE J1939 communication interface
• SmartCraft-compatible monitoring
• Low-coolant-level sensor
• Alternative starting-voltage configuration
• Isolated-ground configuration
• Alternative output voltages
• Single-phase or three-phase windings
• Sound-shield enclosure
• Keel-cooling arrangement
• Dry-exhaust configuration
• Remote fuel-water separator
• Exhaust water separator
• Marine muffler
• Siphon-break kit
• Starting battery
• Anti-condensation heater
• Genuine maintenance kit
• Replacement filters
• Raw-water-pump impellers
• Zinc protection components
• Replacement drive belts

Every accessory should be matched to the full generator model, specification code, installation design, and vessel requirements.

Ideal Marine Generator Replacement and Repower Solution

The Cummins Onan Marine QD 27MDKDU-8253A may be suitable for replacing an older marine generator that has become unreliable, inefficient, undersized, or difficult to maintain.

Owners may consider replacement when an existing generator develops:

• Difficult starting
• Excessive smoke
• Unstable voltage
• Fluctuating frequency
• Repeated overheating
• Coolant or oil leaks
• Excessive vibration
• Increasing operational noise
• High fuel consumption
• Poor parts availability
• Obsolete electrical controls
• Frequent shutdowns
• Insufficient capacity for new equipment
• Rising repair costs

A replacement generator must be selected using more than output alone.

The installation team should compare:

• Rated kilowatt output
• Frequency
• Voltage
• Phase
• Full-load current
• Starting voltage
• Generator dimensions
• Dry and operating weight
• Mounting locations
• Service access
• Raw-water connections
• Exhaust position
• Fuel supply and return
• Ventilation requirements
• AC cable sizing
• Grounding and bonding
• Circuit protection
• Remote-control wiring
• Lifting and installation access

The 8253A specification code should be checked carefully to confirm compatibility with the vessel.

Reliability and Serviceability

Cummins Onan marine generators are designed with routine inspection and servicing in mind.

Service-oriented features may include:

• Accessible oil filter
• Replaceable fuel filter
• Oil-drain hose
• Coolant-recovery bottle
• Accessible raw-water pump
• Running-time meter
• Digital fault diagnostics
• Remote-control connector
• Bulkhead-style service connections
• Single-point lifting provision
• Fluid-containing base
• Brushless alternator design

Cummins advises that regular maintenance is essential for generator performance and operating life. Typical maintenance includes checking the oil, battery connections, filters, coolant, and visible generator components according to the generator’s operation manual. Cummins also states that warranty service should be performed through an authorized dealer, distributor, or certified technician.

Routine service may include:

• Checking engine-oil level
• Checking coolant level
• Inspecting for fluid leaks
• Confirming raw-water flow
• Cleaning the seawater strainer
• Inspecting wet-exhaust hoses
• Checking belts and pulleys
• Replacing engine-oil filters
• Replacing fuel filters
• Inspecting the raw-water impeller
• Inspecting zinc protection
• Testing safety shutdowns
• Inspecting battery terminals
• Checking vibration mounts
• Inspecting electrical connections
• Reviewing fault history

Service intervals must follow the correct Cummins Onan manual for the generator’s model, specification, and operating conditions.

Why Choose the Cummins Onan 27MDKDU-8253A?

The Cummins Onan Marine QD 27MDKDU-8253A is designed for buyers who need dependable onboard electricity, stable 50 Hz output, low-speed diesel operation, advanced monitoring, and marine-specific engineering.

Important reasons to consider this model include:

• Genuine Cummins Onan generator system
• Dependable 27kW output
• Efficient 50 Hz operation
• Durable 1,500 rpm engine speed
• Proven four-cylinder diesel platform
• Brushless four-pole alternator
• Electronic frequency control
• Integral voltage regulation
• Digital fault diagnostics
• Marine heat-exchanger cooling
• Water-cooled exhaust
• Reduced vibration
• Optional sound enclosure
• Remote monitoring capability
• Suitable for new vessels and repower projects
• Access to Cummins parts and service support

Cummins offers marine generator models from approximately 4kW through 110kW and positions its Onan marine range as a dependable source of onboard recreational marine power.

Compatible Products and Accessories

A complete generator installation may require compatible equipment such as:

• Marine starting battery
• Battery cables and terminal covers
• Battery isolator
• Remote generator panel
• Digital generator display
• Vessel-monitoring interface
• Primary fuel-water separator
• Fuel supply and return hoses
• Raw-water seacock
• Marine water strainer
• Raw-water hoses
• Siphon-break assembly
• Wet-exhaust hose
• Waterlift muffler
• Exhaust water separator
• Cooling-water fittings
• AC distribution equipment
• Main circuit protection
• Shore-power transfer system
• Vessel bonding connection
• Machinery-space ventilation
• Sound and heat insulation
• Genuine Cummins Onan oil filters
• Genuine fuel filters
• Raw-water impeller kits
• Zinc protection components
• Recommended engine oil and coolant

Compatibility must be confirmed using the complete model and specification number.

Technical Specifications

The family-level specifications above are based on Cummins documentation for the 27MDKDU. The complete 8253A electrical configuration must be verified through the generator’s nameplate, serial number, factory build sheet, or current Cummins technical documentation.

Worldwide Supply

Coastal Wave Marine supplies Cummins Onan marine generators to yacht owners, shipyards, boat builders, marine engineers, fleet operators, commercial vessel owners, and international marine-equipment buyers.

Our product support may include:

• Generator identification
• Model and specification review
• Electrical-configuration confirmation
• New installation enquiries
• Replacement and repower enquiries
• Compatible-accessory selection
• Shipping preparation
• Export documentation
• International freight coordination
• Technical product information

Before dispatch, buyers should confirm:

• Complete model and specification number
• Generator serial number
• Rated output
• Voltage
• Frequency
• Phase
• Starting voltage
• Sound-shield configuration
• Cooling arrangement
• Exhaust configuration
• Remote monitoring equipment
• Included accessories
• Package dimensions and weight

International delivery depends on destination, freight method, customs requirements, local import regulations, and cargo-handling arrangements.

Frequently Asked Questions

What is the output of the Cummins Onan 27MDKDU-8253A?

The generator is rated at 27kW and is part of the Cummins Onan Quiet Diesel marine generator range.

Is the 27MDKDU a 50 Hz generator?

Yes. The 27MDKDU is a 50 Hz generator that operates at a rated engine speed of 1,500 rpm.

Which engine powers the 27MDKDU?

The generator uses a four-cylinder V3300 diesel engine with approximately 3.318 litres of displacement.

What does the 8253A specification mean?

The 8253A suffix identifies a specific factory build configuration. It may determine details such as voltage, phase, starting voltage, electrical winding, enclosure, control options, and installed equipment.

Is the 27MDKDU-8253A single-phase or three-phase?

The MDKDU family can be produced in different electrical arrangements. The exact phase and voltage of specification 8253A should be confirmed from the nameplate or factory build sheet.

Does it include a sound shield?

A sound shield is available for the generator family, but inclusion on a particular 8253A unit must be confirmed before purchase.

How loud is the Cummins Onan 27MDKDU?

Cummins documentation identifies a sound level of approximately 65 dB(A) at one metre for the sound-shielded configuration under specified test conditions. Actual onboard noise depends on the installation.

What is its approximate fuel consumption?

Published reference figures are approximately 1.9 litres per hour at no load, 4.5 litres per hour at half load, and 9.1 litres per hour at full load.

Can it power marine air-conditioning systems?

Yes, provided the total running and starting demand of the air-conditioning equipment and other connected loads remains within the generator’s capacity.

Does the generator support remote monitoring?

Remote control and digital monitoring options may be available. Depending on configuration, interfaces may support NMEA 2000, SAE J1939, or SmartCraft-compatible monitoring.

What cooling system does the generator use?

It normally uses a closed freshwater engine-cooling circuit with a marine heat exchanger and a separate raw-water circuit.

Can it replace an older 27kW marine generator?

It may be suitable, but voltage, frequency, phase, dimensions, weight, mounting, exhaust, cooling, fuel, electrical protection, and service clearances must all be checked.

Request a Quote

The Cummins Onan Marine QD 27MDKDU-8253A is a dependable 27kW marine generator for vessels that require stable 50 Hz electricity, durable low-speed diesel operation, digital protection, marine-specific cooling, and proven Cummins Onan engineering.

Contact Coastal Wave Marine to request current availability, confirm the exact 8253A electrical configuration, review the included equipment, identify compatible installation accessories, discuss international shipping, and obtain a quotation for the Cummins Onan Marine QD 27MDKDU-8253A.