The Northern Lights L673L is a 0.76 L 3-cylinder naturally aspirated engine rated at 1800 rpm, producing up to 7.38 kW. It powers generator sets from Northern Lights, including the M673, M673LD2, M673LD3 and NL673L4. It holds 3.1 L (0.8 gal) of oil.
Maintenance schedule
| Item | Spec | Capacity | Part # | Interval | |
|---|
| Fuel filter | large spin-on fuel filter | | 24-52020 | 500 hr | Amazon $29.87 eBay $24.71 |
| Oil filter | full flow, spin-on oil filter with bypass | | 24-08001 | 50 hr | Amazon eBay $27.44 |
| Battery | Battery charging alternator with solid state voltage regulator and DC circuit breaker | | — | | |
| Belt | 20 foot (6m) plug-in panel harness | | — | | |
| Oil | | 3.1 l | — | 200 hr | |
| Spark plug | | | — | | |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Procedures
1Soundshield Assembly and Installation installation
⚠ Generator sets with wet exhaust installed near or below the vessel's water line must use a siphon break to prevent backflow of water into the engine, which can ruin the engine and possibly sink the vessel
- Inspect all components for damage and check the packing list before assembly
- Loosen and rotate down original factory lifting points below the highest point on the engine, then retighten
- Select mounting location per IM1000 Installation Manual on a rigid, flat surface above a strong structure
- Position the enclosure so its left side and rear are 6 in recommended (4 in minimum) from bulkheads, avoiding corners with blocked overhead
- Install toe brackets to each corner of the genset base flanges with machine screws, flat washers, and nylock hex nuts
- Install the four vertical extrusions with bolting assemblies; leave loose enough for adjustment during building
- Loosely install front and left-hand side panel retainer blocks to the vertical extrusions
- Position the pre-assembled top frame with triangular penetration plate toward the front and tighten all bolting assemblies progressively
- Install the junction box support cover into the cavity of the support bracket until firmly engaged
- Install the rear sound shield panel, engaging top retaining clips and securing the bottom with bolts, flat washers, and shoulder washers
- Bend the intake air snorkel hose into the rear panel notch without kinking or restricting airflow
- Connect exhaust, sea water, fuel, DC control harness, battery, and AC output leads through the rear panel holes
- If installing a siphon break, replace hole plugs with rubber grommets and route hoses per the IM1000 Installation Manual
- Start the generator set and run under load to check for leaks of fuel, water, or exhaust gas
- Install left side, front, top, and right side panels, and insert foam blocks into the base pan mounting foot pockets
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Common questions
What is the oil capacity of the Northern Lights L673L?
The Northern Lights L673L engine has an oil capacity of 3.1 liters.
What is the displacement of the Northern Lights L673L?
The Northern Lights L673L has a displacement of 0.76 liters with 3 cylinders.
Which generators use the Northern Lights L673L engine?
The Northern Lights L673L powers 4 generator set(s), including Northern Lights M673, Northern Lights M673LD2, Northern Lights M673LD3, Northern Lights NL673L4.
How often should you change the oil in the Northern Lights L673L?
The Northern Lights L673L oil change interval is every 200 hours.
What is a common problem with the Northern Lights L673L engine?
A commonly reported issue on generators using the Northern Lights L673L is: Temperature gauge shows temperature within normal range but shutdown is activated. Fix: Check the engine crankcase oil level. If low, fill with recommended lubricating oil and restart. Watch the oil pressure gauge carefully and shut off the engine if it does not show a normal reading (20-60 PSI) after a few seconds of operation. If the oil level is normal, DO NOT restart the engine. Call your dealer for assistance..