M864W3 Marine Generator - 25 kW / 20 kW

M864W3 Marine Generator - 25 kW / 20 kW

M864W3 Marine Generator - 25 kW / 20 kW

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Northern Lights M864W3 Marine Generator. 25 kW (60Hz) / 20 kW (50Hz). 1800 RPM, quiet, smooth operation, less stress on engine, longer generator life. Automatic voltage regulator protects electronics while starting. Freshwater cooling system, corrosion proof. See specs below. MFG#: M864W3.

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Northern Lights 25kW Marine Generator - M864W3

The perfect generator set, the M864W3 is big enough to run electronic equipment and start large motors, but compact enough to fit into tight engine room spaces.

Running at 1500RPM (50 Hz) & 1800 rpm (60 Hz), this is half the RPMs as most other gen sets built to a smaller envelope or lower price. The lower RPMS mean quieter operation with much less stress on your engine. Over 2,000 hours of operation, your M864W3 will turn 216 million less revolutions, it’s pistons will travel 43,337 fewer miles, and its cylinders will withstand 108 million fewer detonations than most other gen sets of the same size… this means a much longer-lasting gen set with the Northern Lights unit.

Today’s onboard electronic equipment requires clean power. Any disruption of the power supply can cause chaos with your electronics. With the M864W3, an additional winding creates and keeps a clean sine wave. The automatic voltage regulator on the generator protects electronic equipment while enabling electric motor starting.

The cast-iron freshwater cooling system and seawater pump minimizes the mess of belts, hoses and gaskets. Waterproof paint and stainless steel drip pan prevent corrosion and keep engine room clean.

Four platform isolation mounts reduce vibrations and keep the onboard environment smooth and quiet. While quiet on its own, you have the option to further reduce the sound of the generator with a power-coated, aluminum soundshield.

Besides quiet, energy-efficient power supply, the Northern Lights M864W3 meets US EPA III emission requirements, keeping things clean both onboard, and in the environment around you.

All service points are located on one side of the gen set, making maintenance a simple and convenient task. Thanks to the DC logic system, you can troubleshoot and repair the DC power system easily, while a 30 amp AC circuit breaker in the junction box provides short circuit protection.

Automatic safety shutdowns for low oil pressure, high water temperature, and high exhaust temperature are standard.

*Shown here with the M864W3 sound enclosure.

Engine Block

• Four cycle, 4 cylinder, liquid cooled, naturally aspirated, overhead valve diesel.
• Induction hardened crankshaft. Forged carbon steel – stronger than cast iron.
• Helical cut and ground, carbon steel timing and PTO gears reduce noise.
• Cross flow head for efficient breathing. Glow plugs for quick cold starting.

Cooling System

• Freshwater cooling with siphon break.
• Heat exchanger or keel cooled.
• Large, easy-fill single-piece exhaust manifold is freshwater cooled for safety. No hot, dry risers. Fewer troublesome hoses and gaskets. Cast iron to resist corrosion and electrolysis.
• Heat exchanger cooling is standard. Cupro-nickel, tube-type heat exchanger has removable ends for easy cleaning. Rubber impeller seawater pump of bronze and stainless steel is gear driven; no belt.
• Zinc anode electrolysis protection.

Fuel System

• Fuel system is self-venting.
• Injection pump with 5% mechanical governor for close AC frequency control.
• Pintle injectors with replaceable tips.
• Mechanical lift pump with hand primer. No electric pump to fail.
• Large spin-on fuel filter.
• Flexible fuel lines routed to fuel manifold.
• Stop solenoid acts directly on the fuel rack eliminating linkage problems.

Intake and Exhaust

• Meets US EPA Tier III emission standards.
• Washable air cleaner.
• Cast iron, wet exhaust elbow for safety.

Lubrication System

• Full flow, spin-on oil filter with bypass.
• 6.9 qt (6.5 ltr) oil capacity for better lubrication and 200 hour oil change intervals.
• Oil drain for quick, clean oil changes.
• Closed crankcase vent system traps oil vapor and keeps engine room clean.

DC Electrical System

• DC system uses reliable relays instead of an unrepairable printed circuit board.
• 12 volt starter motor and battery charging alternator with regulator and belt guard.
• Standard panel: Remote mount S-3C has hour meter, stop-start switch with run light and preheat switch. Gauges for oil pressure, coolant temp and DC voltage. Safety shutdowns for low oil pressure, high coolant temp and high exhaust temp.
• Expandable to six panels up to 110 feet from the set.
• 20 foot (6m) plug-in panel harness lets you mount your panel anywhere onboard. Better than inaccessible unit mount panels that are prone to vibration problems.

AC Generator

• Northern Lights, direct coupled, brushless AC generator is maintence free. 4 lead, 1 phase, 50 or 60 Hz output standard. 12 lead, 3 phase optional. Conservative heat rise rating: 95oC/50oC ambient.
• Automatic voltage regulator (AVR) is powered by dedicated AC winding for true 300% short circuit capability and circuit breaker protection. Quick ±1% RMS no load to full load voltage regulation.
• Generator features high quality, Class “H” epoxy insulation, accessible diodes, over-sized bearings and junction box for wiring.

Special Equipment

• Welded steel base frame with drip pan.
• Operator’s and parts manuals standard.
• Four plateform mounts isolate vibration.
• White, long-life polyurethane paint.


60 Hz @ 1800 rpm

25 Kw

50 Hz @ 1500 rpm

20 Kw


4 inline


3.4 in (86 mm)


4.2 in (107 mm)


152 cid (2.49 ltr)

Fuel System:





52.9 in (1350 mm)

Length with Enclosure:

52.9 in (1350 mm)


24.2 in (696 mm)

Width with Enclosure:

24.2 in (696 mm)


26.5 in (672 mm)

Height with Enclosure:

27.7 in (703 mm)


993 lbs (450 kg)

Enclosure Weight:

140 lbs (64 kg)