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Northern Lights NL368 Engine

Name: Northern Lights NL368 Engine
Brand: Northern Lights

The Northern Lights NL368 is a 3.5 L 4-cylinder naturally aspirated engine rated at 1800 rpm, producing up to 36 kW. It powers generator sets from Northern Lights, including the NL374, NL378, NL484 and NL488. It holds 3.5 L (0.9 gal) of oil and 10 L (2.6 gal) of coolant.

Also known as: Northern Lights NL368

3.5 L

Displacement

Cylinders

1800 rpm

Rated speed

36 kW

Gross power

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures

Engine specifications

Oil capacity	3.5 L
Coolant capacity	10.0 L
Displacement	3.5 L
Cylinders	4
Aspiration	naturally aspirated
Rated speed	1800 rpm
Gross power	36 kW

Generator sets powered by this engine

Northern Lights NL374 Northern Lights NL378 Northern Lights NL484 Northern Lights NL488

How to read your Northern Lights engine serial & model number →

Common problems

Temperature gauge shows temperature within normal range but shutdown is activated
Fix: Check the engine crankcase oil level. If the oil level is 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.
Temperature gauge shows temperature above 205°F (97°C)
Fix: Shut off the engine immediately. Use the Trouble Shooting Guide in this manual to isolate the cause of the overheat.
Starter Inoperative
Cause: Check DC circuit breaker Loose or corroded connections Low battery output Defective electrical system ground wire:
Fix: * If the breaker is tripped, reset it. * Clean and tighten loose battery and harness plug connection. * Check specific gravity of each battery. * Check electrolyte level of each battery. * Repair or replace.
Starter Cranks Slowly
Cause: Low battery output Check specific gravity of each battery Check electrolyte level of each battery Crankcase oil too heavy
Fix: * Battery is too small. * Battery cables are too small. * If low, fill cells with distilled water. * Fill with oil of appropriate viscosity. * Clean and tighten loose connections.
Low Oil Pressure
Cause: Low oil level, Improper type of oil, Partially plugged oil filter
Fix: Fill crankcase to proper level, Drain and fill crankcase with correct oil, Replace filter
Lack of Engine Power
Cause: Intake air restriction, Clogged primary fuel filter element, Clogged secondary fuel filter element, Improper type of fuel, Overheated engine, Below normal engine temperature, Dirty or faulty injection nozzles
Fix: Service air cleaner, Clean or replace filter element, Replace filter element, See “Engine Overheats” in next category, Reset valves. Best done by dealer, Replace injectors. Best done by dealer
High Oil Consumption
Cause: Break-in period, Crankcase oil too light, Oil leaks
Fix: Oil consumption decreases after break in, Use proper viscosity oil, Check for leaks in lines around gaskets and drain plug
High Fuel Consumption
Cause: Improper type of fuel, Clogged or dirty air cleaner, Improper valve clearance, Injection nozzles dirty, Injection pump out of time, Engine not at proper temperature
Fix: Use correct fuel for temperature, Service air cleaner, See your dealer, See your dealer, See your dealer, Check your thermostats, Check water temperature with thermometer and replace gauge if necessary
Entire Electrical System Does Not Function
Cause: Check DC circuit breaker Faulty connection Sulfated or worn out batteries
Fix: * If breaker is tripped, reset it. * Clean and tighten battery and harness plug connections. * Check specific gravity and electrolyte level of each battery.
Engine Runs irregularly or Stalis Frequently
Cause: Below normal engine temperature, Clogged primary fuel filter element, Clogged secondary fuel filter element, Water or dirt in the fuel system, Dirty or faulty injection nozzles, Air in fuel system, Improper type of fuel
Fix: Clean or replace filter element, Replace secondary filter element, Drain, flush, fill and bleed system, Inspect clamps and hoses on suction side of fuel pump for air leak, Consult fuel supplier and use proper type of fuel for operating condition
Engine Overheats
Cause: Low coolant level, Cooling system needs flushing, Defective thermostat, Defective temperature gauge
Fix: Fill tank or radiator to proper level, Check hoses for loose connections and leaks, Flush cooling system, Remove and check thermostat, Check water temperature with thermometer and replace gauge if necessary
Engine Knocks
Cause: Insufficient oil, Injection pump out of time, Below normal engine temperature, Engine overheating
Fix: Call your dealer, Call your dealer, Check your thermostats, Check water temperature to see if temperature gauge is working properly, See “Engine Overheating” section
Engine Hard to Start or Will Not Start
Cause: Improper starting procedure No fuel Low battery output Excessive resistance in starting circuit Crankcase oil too heavy Improper type of fuel Water, dirt or air in fuel system Clogged primary fuel filter element — Clogged secondary fuel filter element Dirty or faulty injection nozzles
Fix: * See starting section of this manual. Take special note of Bypass Switch operation. * Check level of fuel in fuel tank. * Check electrolyte level and condition. * Clean and tighten all battery connections. ° Use oil of proper viscosity. ° Consult fuel supplier and use proper type of fuel for operating condition. ¢ Drain, flush, fill and bleed system. ¢ Clean or replace
Engine Emits White Smoke
Cause: Cold engine
Fix: Warm up engine to normal operating temperature
Engine Emits Black or Gray Exhaust Smoke
Cause: Clogged or dirty air cleaner, Defective muffler (back pressure too high), Improper fuel Injection nozzles dirty, Engine out of time
Fix: Service air cleaner, Have dealer check back pressure, See your dealer, See your dealer

Compiled from service & troubleshooting documentation across every generator set that uses the Northern Lights NL368.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Air cleaner element		—	100 hr
Fuel filter	Secondary fuel filter		24-50012	200 hr	Amazon eBay
Oil filter	Recommended oil filter		—	100 hr
Battery	Battery		—	50 hr
Belt	V-Belt		—	50 hr
Oil	Recommended oil	3.5 L	—	100 hr
Spark plug	Spark plug		—	600 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Electrolyte level in batteries	Check	50 hr
V-belt tension	Check	50 hr		First service — After first 50 hours
Valves	Adjust	50 hr		First service — Adjust after first 50 hours
battery electrolyte	Check	50 hr	1 mo	Add distilled water to recommended level
Radiator	Clean	100 hr		In dusty applications; clean in reverse direction of airflow
air cleaner	Check	100 hr		More often in dusty conditions
batteries, cables and terminals	Clean	100 hr		Clean corrosion with water and baking soda; tighten and grease terminals
engine oil and filter	Change	100 hr		First service — First change at 50 hours, then 100 hours; every 100 hours or six weeks in cold weather
Fuel system	Other	200 hr		Bleed the fuel system
Secondary fuel filter	Change	200 hr
primary fuel filter element	Change	200 hr		As often as necessary
Batteries	Test	600 hr		Check state of charge with hydrometer
Cooling system	Other	600 hr		Check and flush
Injectors	Check	600 hr
Valve clearances	Check	600 hr
cooling system	Clean	600 hr	12 mo	Flush every 600 hours or 12 months, whichever comes first
injectors	Inspect	600 hr		Check by Northern Lights dealer or injection repair station
valve clearances	Adjust	600 hr		First service — Readjust after first 50 hours, then every 600 hours
Fuel injection pump	Check	2400 hr		Check pump settings, maximum speed, idle speed and exhaust smoke
fuel injection pump	Test	2400 hr		Check pump settings, maximum speed, idle speed and exhaust smoke
cylinder head bolts	Adjust	50 hr		First service — Retighten after first 50 hours with engine cold

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	V-belt deflection	3/8	in
Gap	V-belt deflection	10 - 15	mm	correct tension
Gap	V-belt deflection at midpoint between crankshaft and alternator pulleys	3/8	inch	correct tension
Other	Compression ratio	18:0
Other	Compression ratio	23:0
Pressure	Engine oil pressure (normal reading)	20 - 60	PSI	running
Pressure	Maximum exhaust back pressure	48	in (1200 mm) H2O
Pressure	Minimum oil pressure	15	PSI	running, Series 3 and 6 panels
Pressure	Oil pressure (minimum)	above 15	PSI
Pressure	Oil pressure (normal operating)	20-60	PSI
Pressure	Radiator filler cap release pressure	0.9	kgm/cm2
Pressure	Radiator filler cap release pressure	12	PSI
Pressure	Radiator pressure cap release	0.9	kg/cm2	pressure valve
Pressure	Radiator pressure cap release	12	PSI	pressure valve
Temperature	Maximum exhaust temperature	1022	deg F
Temperature	Maximum exhaust temperature	550	deg C
Temperature	Water temperature (normal)	below 200	°F
Temperature	Water temperature (shut down immediately)	above 205	deg F	running
Temperature	Water temperature (shutdown)	above 205	°F
Temperature	Water temperature gauge (normal, maximum)	below 200	deg F	running
Torque	Cylinder head bolts	10.5 - 11.5	kgf-m	cold
Torque	Cylinder head bolts	27.5 - 30.5	ft/lb	engine cold; bolt size 8mm
Torque	Cylinder head bolts	3.8 - 4.2	kgf-m	engine cold; bolt size 8mm
Torque	Cylinder head bolts	44 - 47	ft/lb	engine cold; bolt size 9mm
Torque	Cylinder head bolts	49 - 52	ft/lb	engine cold; bolt size 9mm
Torque	Cylinder head bolts	49.0 - 52.0	ft-lb	cold
Torque	Cylinder head bolts	6.0 - 6.5	kgf-m	engine cold; bolt size 9mm
Torque	Cylinder head bolts	6.8 - 7.2	kgf-m	engine cold; bolt size 9mm
Torque	Cylinder head bolts	63 - 67	ft/lb	engine cold; bolt size 10mm (printed 384)
Torque	Cylinder head bolts	63.0 - 67.0	ft-lb	cold
Torque	Cylinder head bolts	76.0 - 83.0	ft-lb	cold
Torque	Cylinder head bolts	8.7 - 9.3	kgf-m	engine cold; bolt size 10mm (printed 384)
Torque	Glow plugs	1.5 - 2.0	kgf-m	new glow plugs
Torque	Glow plugs	11 - 14	ft/lbs	new glow plugs
Torque	Injector (screw-in)	36 - 39	ft-lbs	NL368 and NL374, new copper sealing washer
Torque	Injector (screw-in)	5.0 - 5.4	kgf-m	NL368 and NL374
Torque	Injector hold down bracket nuts	0.7 - 0.9	kgf-m	NL378, NL484, NL488
Torque	Injector hold down bracket nuts	5 - 6.5	ft-lbs	NL378, NL484, NL488
Torque	Injector hold-down nuts	0.7 - 0.9	kgf-m
Torque	Injector hold-down nuts	5 - 6.5	ft-lbs
Valve clearance	Intake and exhaust valves	0.006 - 0.010	in	engine cold and not running
Valve clearance	Intake and exhaust valves	0.15 - 0.25	mm	engine cold and not running
Voltage	D.C. voltmeter reading	11 - 15	volts	at 80 deg F (25 deg C) ambient
Voltage	DC voltmeter	11 - 15	volts	at 80°F (25°C) ambient temperature

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Notes
Coolant	50% water / 50% ethylene glycol antifreeze			Recommended as good year-round coolant
Engine oil	API Service CC/CD/CE single viscosity oils	API Service CC/CD/CE		Use proper weight for average ambient temperature
Engine oil	API Service CC/CD/SF multi-viscosity oils	API Service CC/CD/SF
Engine oil	SAE 5-20W (multi-viscosity)		below -23°C	Below -10 deg F (-23 deg C); more oil consumption with SAE 5W and 5-20W
Engine oil	SAE 5W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	below -23°C	Below -10°F (-23°C)
Engine oil	SAE 5W-20W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	below -23°C	Below -10°F (-23°C)
Engine oil	SAE-5W (single viscosity)		below -23°C	Below -10 deg F (-23 deg C)
Engine oil	SAE 10W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	-23°C to 0°C	-10 to 32°F (-23 to 0°C)
Engine oil	SAE 10W-30W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	-23°C to 0°C	-10 to 32°F (-23 to 0°C)
Engine oil	SAE 15-40W (multi-viscosity)		above 0°C	Above 32 deg F (0 deg C); also listed 5-40W in printed chart
Engine oil	SAE 15W-40W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	above 0°C	Above 32°F (0°C)
Engine oil	SAE 30W	API Service CC/CD/CE single viscosity or CC/CD/SF multi-viscosity	above 0°C	Above 32°F (0°C)
Engine oil	SAE-30W (single viscosity)		above 0°C	Above 32 deg F (0 deg C)
Fuel	Grade No. 1 diesel	ASTM D975	below 0°C	Below freezing and for all temperatures above 5,500 ft (1500 m) altitude
Fuel	ISO-8217-DMA / BS 2869 Part 1 Class A1 / BS 2869 Part 2 Class A2	ISO-8217-DMA; BS 2869		International fuel specifications; sulphur less than 1% (preferably less than 0.5%); cetane number minimum 45
Fuel	No. 1 diesel	ASTM D975	below 0°C	Use below freezing and for all temperatures at altitude above 5,500 ft. (1500 meters)
Fuel	Grade No. 2 diesel	ASTM D975	above 0°C	Above freezing 32 deg F (0 deg C)
Fuel	No. 2 diesel	ASTM D975; ISO-8217-DMA; BS 2869 Part 1 Class A1; BS 2869 Part 2 Class A2	above 0°C	Use above freezing 32°F (0°C); less than 1% sulphur (preferably less than 0.5%); cetane minimum 45

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjusting Valve Clearances adjustment

⚠ Adjust valves after cylinder head bolts have been tightened

Tools: feeler gauge

Adjust after first 50 hours, then every 600 hours.
Do adjustment with engine cold and not running; remove rocker arm cover.
Turn engine by hand until valves rock, then one more full turn.
Loosen lock nut and adjust clearance with adjustment screw.
Set both intake and exhaust to 0.006-0.010 in (0.15-0.25 mm).
Repeat for each cylinder and replace rocker arm cover.

V-Belt Tension Adjustment adjustment

Press belt with thumb at midpoint between crankshaft and alternator pulleys.
Tension is correct when belt depresses about 3/8 inch (10-15 mm).

Valve Clearance Adjustment adjustment

Tools: thickness gauge, wrench

Readjust valve clearance after first 50 hours of operation; adjust valves every 600 hours thereafter.
Do adjustment after cylinder head bolts have been re-tightened; engine should be cold and not running.
Remove the rocker arm cover.
Turn engine by hand until inlet valve starts to open and exhaust valve starts to close (valves rocking), then turn crankshaft one more full turn and adjust clearance on both valves for this cylinder.
Insert thickness gauge between rocker arm and valve cap; loosen lock nut and adjust with adjustment screw.
Clearance on both intake and exhaust valves should be 0.006 - 0.010 in. (0.15 - 0.25 mm).
Repeat for each cylinder.
Replace the rocker arm cover.

Air Cleaner Service maintenance

⚠ Make absolutely sure no impurities enter the engine while changing the element.

⚠ Do not run the engine with the air cleaner removed.

Check dust trap on bottom of air cleaner daily; squeeze rubber cap lips to let dirt fall out.
Visually inspect air cleaner every 100 hours; check more often in dusty conditions.
An element cannot be cleaned; replace dirty elements when necessary.

Bleeding the Fuel System maintenance

⚠ Escaping diesel fuel under pressure can penetrate skin and cause serious injury

⚠ Use cardboard or wood, not hands, to search for leaks

Loosen bleed screw on top of fuel filter.
Pump hand primer on fuel lift pump until pure fuel with no bubbles escapes.
Tighten bleed screw.
Loosen bleed screw on injection pump, pump primer until bubble-free, tighten.
If engine will not start, loosen a fuel line at the injector and crank until pure fuel escapes.

Break-In Period maintenance

First 100 hours on a new or reconditioned engine are critical to life and performance.
Constantly check engine temperature and oil pressure gauges.
Oil consumption is greater during break-in as piston rings take time to seat.
Change engine oil and filter at 50 hours.
Change oil and filter again at 100 hours.
Retighten head bolts at 50 hours.
Maintain at least a 75% load for the first 100 hours; if not possible, no less than 50% load.
Vary the load to help seat the rings.

Changing Lube Oil Filter maintenance

⚠ Overtightening can damage the filter housing.

⚠ Do not use a wrench to tighten the filter.

Tools: filter wrench

Use a filter wrench to remove old filter; dispose of filter in approved manner.
Make sure gasket from old filter is removed and discarded; clean mount face.
Spread a thin film of engine oil on the new filter rubber gasket.
Screw filter on nipple until gasket meets the sealing surface.
Tighten filter one-half turn farther using hands only.
Fill engine with recommended oil.
Start engine and check for leakage.
Stop engine, wait 3 minutes, and check oil level; add oil if necessary.

Changing Lube Oil and Filter maintenance

⚠ Overtightening can damage filter housing

⚠ Never use a flushing oil

Tools: filter wrench

Loosen plug in oil pan and drain oil; dispose of waste oil properly.
Remove old filter with a filter wrench; discard old gasket.
Clean mount face and oil the new filter gasket.
Screw filter on until gasket meets sealing surface, then 1/2 turn by hand.
Fill engine with recommended oil.
Start engine, check for leakage, stop, wait 3 minutes, check level.

Cooling System Flushing maintenance

Flush the cooling system every 600 hours or every 12 months, whichever comes first.
Remove radiator cap and open drains on radiator and engine block.
Pour clean water into radiator until water coming from radiator is clear of discoloration.
Close radiator drain and continue flushing until water from engine drain is clear.
Open all drains and drain engine and radiator completely.
Close drains and refill radiator with recommended coolant mixture (50% water / 50% ethylene glycol antifreeze).
Check hoses and connections and repair any leakage.
Start engine and check for leaks; run engine for five minutes, then shut it down.
Let engine cool, then check coolant level and add as needed.

Flushing the Cooling System maintenance

⚠ Allow engine to cool before working on cooling system

⚠ Open filler cap carefully using protective clothing

Flush every 600 hours or every 12 months, whichever comes first.
Remove radiator cap and open radiator and engine block drains.
Flush until water from both drains is clear of discoloration.
Drain completely and refill with recommended coolant mixture.
Check hoses and connections and repair any leakage.
Start engine, run 5 minutes, shut down, let cool, check coolant level.

Servicing the Air Cleaner maintenance

⚠ Do not run engine with air cleaner removed

⚠ Ensure no impurities enter engine while changing element

Check dust trap daily; squeeze rubber cap lips to empty dirt.
Visually inspect air cleaner every 100 hours.
Replace element when necessary; an element cannot be cleaned.

Winterizing / Out-of-Service maintenance

⚠ Store the set in a dry, protected place

Drain and flush radiator and cooling system; leave dry or refill with antifreeze mixture.
Fill fuel tank or add biocide per manufacturer instructions.
Seal air cleaner inlet, exhaust opening, crankcase breather pipe and fuel tank vent.
Change crankcase oil and filter.
Loosen the alternator belt.
Disconnect and clean battery; remove to warm storage if possible.
Clean outside of unit and put corrosion preventative on exposed metal.

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 NL368?

The Northern Lights NL368 engine has an oil capacity of 3.5 liters.

What is the displacement of the Northern Lights NL368?

The Northern Lights NL368 has a displacement of 3.5 liters with 4 cylinders.

Which generators use the Northern Lights NL368 engine?

The Northern Lights NL368 powers 4 generator set(s), including Northern Lights NL374, Northern Lights NL378, Northern Lights NL484, Northern Lights NL488.

How often should you change the oil in the Northern Lights NL368?

The Northern Lights NL368 oil change interval is every 100 hours.

What is a common problem with the Northern Lights NL368 engine?

A commonly reported issue on generators using the Northern Lights NL368 is: Temperature gauge shows temperature within normal range but shutdown is activated. Fix: Check the engine crankcase oil level. If the oil level is 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..