Home›Northern Lights›Northern Lights LP668T

Northern Lights LP668T Generator Set

The Northern Lights LP668T is a 129 kW (174 kVA) prime generator set powered by a John Deere Powertech 6068 engine. It holds about 19 L (5.0 gal) of oil. Starting uses battery rated 800 CCA at 12 V. The set weighs about 590 kg (1301 lb).

4.5 L
Displacement
19.0 L
Oil capacity
3
Document types

How to read your Northern Lights serial & model number →

Service parts for the LP668T

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required

Fuel system

1 required

Oil system

1 required

Belts

1 required
R123437Belt$41.05eBay

Cooling system

1 required
20-00002Coolantsee priceAmazon

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Prime power129 kW
Oil capacity19.0 L
Battery cranking800 CCA
Battery voltage12 V
Dry weight590 kg

Engine

John Deere Powertech 6068
Displacement4.5 L
AspirationNaturally aspirated

Maintenance & consumables

for the John Deere Powertech 6068
ItemSpecCapacityPart #Interval
Air filterAir Filter24-21000 Amazon eBay
Fuel filter24-51005600 hr Amazon eBay $24.99 eBay $17.99 NAPA $38.86 KuduParts $18.00
Oil filterOil Filter24-01002 eBay $24.44 eBay $24.44
BeltDrive Belt, LP-MP668T-H (with turbo)R123437 eBay $41.05 FridayParts $47.99
Coolant22.0 L20-00002600 hr Amazon eBay
OilAPI CC/CD or CD/CG-4/CF-4; ACEA E3/E217.0 L—200 hr

Service intervals

22
ItemActionHoursMonthsNotes
Battery electrolyteCheck50 hrEvery 50 hours or once per month
Air cleanerInspect100 hrInspect every 100 hours; replace every 600 hours or yearly
Batteries, cables and terminalsClean100 hrCheck and clean every 100 hours
Air cleanerCheck200 hrEvery 200 hours
Engine oilChange200 hrFirst service — Every 200 hours
Lube oil filterChange200 hrFirst service — Every 200 hours
Primary fuel filter elementChange200 hrEvery 200 hours
Turbocharger air, oil and cooling linesCheck200 hrCheck for leakage every 200 hours
Zinc electrodesCheck200 hrEvery 200 hours
Air cleanerReplace600 hr12 moEvery 600 hours or yearly
Batteries state of chargeCheck600 hr12 moEvery 600 hours or yearly
Cooling systemClean600 hr12 moCheck and flush every 600 hours or yearly
Fuel injectorsCheck600 hr12 moEvery 600 hours or yearly; by dealer
Raw water pump impellerChange600 hr12 moEvery 600 hours or yearly
Secondary fuel filterChange600 hr12 moEvery 600 hours or yearly
Turbocharger boost pressureCheck600 hr12 moEvery 600 hours or yearly
V-beltCheck600 hr12 moEvery 600 hours or yearly
Battery conditionTest750 hrCheck with hydrometer every 750 hours
Valve clearancesAdjust1200 hrFirst service — Every 1200 hours
Fuel injection pumpCheck2400 hrEvery 2400 hours
Gear oil coolerClean2400 hrCheck and clean every 2400 hours
Heat exchangerClean2400 hrCheck and clean every 2400 hours

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

31
TypeItemValueUnitCondition
OtherCoolant mixture optimum50% distilled water / 50% EGCoptimum
OtherFiring order, 4-cylinder engines1-3-4-2
OtherFiring order, 6-cylinder engines1-5-3-6-2-4
OtherMinimum battery capacity, 12V640CCA
OtherMinimum battery capacity, 12V800CCA
OtherSupplemental coolant additive concentration3% by volumein 50% water / 50% EGC mixture
PressureCoolant filler cap pressure7PSI (0.5 bar)
PressureEngine oil pressure minimum15PSIat speed higher than idling
SpeedLow idle700RPM
SpeedMaximum engine speed when shifting marine gear800RPM
SpeedMaximum working engine speed, continuous duty2200RPM
SpeedMaximum working engine speed, light commercial craft2400RPM
SpeedMaximum working engine speed, pleasure craft2400RPM
SpeedMaximum working engine speed, pleasure craft2500RPM
SpeedWarm-up engine speed1000RPM3 to 5 minute warm-up
TemperatureCoolant temperature maximum normal200°F (94°C)do not exceed
TemperatureCoolant temperature shutdown205°F (97°C)shut off engine immediately
TemperatureRaw water inlet maximum temperature85°F (30°C)
TorqueFuel delivery pressure lines20 foot lbs. (27 N·m)ft-lb/N·m
TorqueFuel line connection at injection nozzle20 foot lb. (27 N•m)ft-lb/N·m
TorqueFuel supply line at injection pump22 ft. lb. (30 N•m)ft-lb/N·m
TorqueInjection pump cover plate cap screws1.7 lb-ft. (2 N•m)ft-lb/N·m
TorqueInjection pump drive gear retaining nut (DB2)90 lb-ft. (122 N•m)ft-lb/N·m
TorqueInjection pump drive gear retaining nut (DB4)150 lb-ft. (203 N•m)ft-lb/N·m
TorqueInjection pump mounting hex nuts20 foot lbs. (27 N·m)ft-lb/N·m
TorqueNozzle hold-down cap screws27 foot lb. (37 N•m)ft-lb/N·m
Valve clearanceExhaust valve clearance0.016-0.019 in. (0.41-0.48 mm)in/mmengine cold
Valve clearanceIntake valve clearance0.012-0.015 in. (0.31-0.38 mm)in/mmengine cold
VoltageStarting voltmeter minimum12 volts (24 volts for 24 volt systems)Vbefore starting
VoltageVoltmeter reading, 12 volt systems13 to 14voltsat 60°F (16°C)
VoltageVoltmeter reading, 24 volt systems26-28voltsat 60°F (16°C)

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

FluidGradeStandardAmbientCapacityNotes
CoolantEthylene glycol concentrate (EGC) + quality water + SCAASTM D 4985P; SAE J1941; GM1899M; or GM6038M18.9 LLP445 series; 5 US gal. Optimum 50% distilled water/50% EGC; freeze -37°C, boil +109°C.
Engine oilJohn Deere Engine Break-In Oil; API Service CE; ACEA Specification E1Use during first 100 hours of operation.
Engine oilSAE-5W; SAE5-20WAPI CC/CD, CD/CG-4/CF-4; ACEA E3/E2below -23°CBelow -10°F (-23°C).
Engine oilSAE-10W; SAE10-30WAPI CC/CD, CD/CG-4/CF-4; ACEA E3/E2-23°C to 0°C-10°F to 32°F (-23°C to 0°C).
Engine oilSAE-30W (single viscosity); SAE15-40W (multi-viscosity)API CC/CD, CD/CG-4/CF-4; ACEA E3/E2above 0°CAbove 32°F (0°C).
FuelGrade No. 1 dieselASTM D975below 0°CBelow freezing and all temperatures above 5,500 ft (1500 m).
FuelGrade No. 2 dieselASTM D975above 0°CAbove freezing 32°F (0°C); cetane minimum 45; sulfur less than 1% (preferably less than 0.5%).

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

Procedures

12
Check and Adjust Valve Clearances adjustment

Tools: JDE 820 or JDE 83 Flywheel Turning Tool, JDE 81-4 Timing Pin

  1. Remove rocker arm cover with ventilator tube.
  2. Remove plastic plugs in engine timing holes on front side of flywheel.
  3. Rotate flywheel clockwise with Flywheel Turning Tool until Timing Pin engages timing hole; No. 1 cylinder rocker arms loose at TDC.
  4. If not at TDC, remove timing pin, rotate flywheel one complete turn, and reinstall pin.
  5. Check valve clearances with engine cold.
  6. For 4-cylinder: adjust No. 1 and No. 3 exhaust and No. 1 and No. 2 intake at No. 1 TDC; rotate 360° and adjust remaining.
  7. For 6-cylinder: adjust No. 1, No. 3, No. 5 exhaust and No. 1, No. 2, No. 4 intake at No. 1 TDC; rotate 360° and adjust remaining.
Air Cleaner Service maintenance

⚠ Do not run engine with air cleaner removed.

  1. Inspect air cleaner every 100 hours; replace filter every 600 hours or yearly, whichever comes first.
  2. Loosen hose clamp and attaching strip; clean rubber tube at cleaner.
  3. Ensure rubber tube is in good condition and new filter is clean and installed properly.
  4. Start engine and check for leaks.
Bleed Fuel System maintenance

⚠ Escaping diesel fuel under pressure can penetrate skin.

Tools: Backup wrench

  1. Loosen bleed plug on fuel filter.
  2. Operate primer pump lever on fuel transfer pump until air bubbles are expelled and clear fuel escapes.
  3. Tighten bleed plug.
  4. If engine will not start, loosen fuel supply pipe at pump and prime until free of air; retighten to 22 ft. lb. (30 N•m).
  5. If still not starting, loosen fuel line at injection nozzle and crank with throttle full until fuel without air flows; tighten to 20 foot lb. (27 N•m).
Change Engine Oil maintenance

Tools: Oil drain hose, Hand pump (optional drain pump)

  1. For marine generator sets, remove plug from base frame outlet and screw in owner-supplied drain hose.
  2. Open valve at oil pan outlet and drain oil into suitable container.
  3. Close valve, remove drain hose, and replace plug.
  4. Refill engine with recommended oil.
  5. For propulsion engines with optional drain pump, remove dipstick, unscrew dipstick tube, insert hand pump to bottom of oil pan, and drain by pumping.
  6. Replace dipstick tube and dipstick; refill engine with recommended oil.
Change Lube Oil Filter maintenance

⚠ Overtightening can damage filter housing.

Tools: Filter wrench

  1. Use filter wrench to remove old filter; dispose in approved manner.
  2. Make sure gasket from old filter is removed and discarded.
  3. Lubricate rubber gasket on new filter and screw on nipple until gasket meets sealing surface.
  4. Using hands only, tighten filter one-half turn farther.
  5. Fill engine with recommended oil; start engine and check for leakage; stop and check oil level.
Clean Heat Exchanger maintenance
  1. Drain the cooling system.
  2. Remove cooling water pipes between heat exchanger and water pump inlet.
  3. Disconnect hose to seawater pump.
  4. Unscrew attaching bolts holding heat exchanger to expansion tank.
  5. Remove bolts holding heat exchanger cover.
  6. Wash core inside and out; clean accessible parts of housing.
  7. Reassemble using new gaskets and sealing rings.
Flush Cooling System maintenance

⚠ Cooling water is extremely hot; allow engine to cool before working.

  1. Stop engine and allow to cool.
  2. Close seacock.
  3. Remove pressure cap from expansion tank; open cooling system air vent on turbocharger if applicable.
  4. Open drains on exhaust manifold and engine block; drain fresh water system.
  5. Pour clean water into expansion tank until drain water is clear; close drains.
  6. Fill with recommended coolant mixture; close air vent.
  7. Open seacock; start engine and check hoses and connections for leaks.
Replace Raw Water Pump Impeller maintenance

⚠ Keep extra impeller and cover gasket onboard.

Tools: Water pump pliers

  1. Remove pump end cover.
  2. Remove impeller with water pump pliers; remove all pieces of failed impeller.
  3. Clean inside of housing.
  4. Press in new impeller and place sealing washer in outer end of impeller center.
  5. Replace cover using new gasket.
Replace Secondary Fuel Filter maintenance

⚠ Dirt can be washed into fuel injection system causing severe damage.

  1. Turn off the fuel.
  2. Open filter drain plug and drain the filter.
  3. Turn filter clamp counterclockwise until cartridge slides out.
  4. Install new filter cartridge 24-51005 after ensuring mounting plate surfaces are clean.
  5. Turn on the fuel.
  6. Bleed fuel system if opened.
Service Zinc Anodes maintenance

Tools: Scraper or steel brush

  1. Drain raw water from heat exchanger.
  2. Remove zinc holders from back of tank and from front and port side of heat exchanger.
  3. Scrape or steel brush zinc electrode clean.
  4. Replace zinc if more than 50% eroded.
  5. Reinstall zinc holders with clean threads and good metal-to-metal contact.
Winterize / Out-of-Service maintenance
  1. Shut off sea cocks before opening drain cocks.
  2. Drain seawater cooling systems completely.
  3. Drain seawater supply lines and wet exhaust line.
  4. Loosen seawater pump cover and drain pump.
  5. Check freshwater antifreeze mixture; refill water if necessary.
Before Starting operation

⚠ Use protective clothing and open filler cap carefully when engine is warm.

  1. Check expansion tank water level; should be about 1 3/4 in. (4-5 cm) below filler cap sealing surface when cold.
  2. Check crankcase oil level; keep between the "waffled area" and the "oo".
  3. Check fuel tank level and open any fuel valves.
  4. Check reverse gear oil level per Gear Owner's Manual.
  5. Close seacock, clean strainer, and reopen seacock.
  6. Place battery switch in ON position.

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 engine does the Northern Lights LP668T use?

The Northern Lights LP668T is powered by the John Deere Powertech 6068 engine.

What is the oil capacity of the Northern Lights LP668T?

The Northern Lights LP668T has an engine oil capacity of 19 liters (20.1 US quarts), per the manufacturer specification sheet.

How much does the Northern Lights LP668T weigh?

The Northern Lights LP668T has a dry weight of 590 kg (1300 lb).

What size battery does the Northern Lights LP668T need?

The Northern Lights LP668T uses 12 V each, 800 CCA, per the manufacturer specification sheet.

What oil filter fits the Northern Lights LP668T?

The Northern Lights LP668T uses oil filter part number 24-01002.

What fuel filter fits the Northern Lights LP668T?

The Northern Lights LP668T uses fuel filter part number 24-51005.

What air filter fits the Northern Lights LP668T?

The Northern Lights LP668T uses air filter part number 24-21000.

Troubleshooting

6

Symptoms & remedies

SymptomCauseRemedy
Engine failuresFailures often occur in remote areas far from competent assistance.
Battery charging regulator could be ruinedSwitch is turned OFF while the engine is running
Engine fails to start on first attemptDo not crank the starter for more than 15 seconds consecutively. Ensure the starter has stopped completely before re-engaging.
Engine temperature rises over 200°F (94°C)Shut down the engine and investigate the cause of overheating.
Shutdown is activated and temperature gauge shows within normal rangeCheck 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 after a few seconds of operation. If the oil level is normal, DO NOT restart the engine. Call your Northern Lights or Lugger dealer for assistance.
Engine temperature rises above 205°F (97°C)Shut off the engine immediately.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Repair guides

6

Step-by-step procedures compiled from the Northern Lights service manual for this model.

Parts

108
Part #DescriptionQtySystem
11-21011Gasket2Gasket Amazon eBay
11-31031Gasket, Turbo Oil Return1Gasket Amazon eBay
11-31635Gasket, Turbo Exhaust (K27)1Gasket Amazon eBay
18-19501Hose 1-1/4" ID x 3-1/2" 3 Ply Silicone3Hose eBay
18-21016Hose, 2" I.D. x 1-3/4" 3 Ply Silicone1Hose Amazon eBay
18-31605Hose, 1-1/4 x 32" Wire Reinforced1Hose Amazon eBay
22-40440Magnetic Pick-Up 3/4-16 x 2-1/4" with Plug-In Pigtail Harness1Sensor eBay
22-40907Engine Temperature Switch, 205°F1Sensor eBay
22-40915Switch, Pressure 15 PSI1Sensor Amazon eBay
22-41016Oil Pressure Sender1Sensor Amazon eBay $66.00
22-41026Coolant Temperature Sender1Sensor Amazon eBay
22-42802Coolant Temperature Sender1Sensor Amazon eBay
22-42803Oil Pressure Sender1Sensor Amazon eBay
24-01002Oil Filter1Oil filter eBay $24.44 eBay $24.44
24-21000Air Filter1Air filter Amazon eBay
24-51003Fuel Filter without Drain Valve1Fuel filter eBay $35.00
24-51005Fuel Filter with Metal Drain Valve1Fuel filter Amazon eBay $24.99 eBay $17.99 NAPA $38.86 KuduParts $18.00
25-11011Impeller with Gasket1Impeller Amazon eBay $39.99
25-19501Raw Water Pump Assembly (Includes all keys)1Pump eBay $399.95
25-19507Seal, Lip Type1Seal eBay
25-19508Seal, Mechanical/Carbon1Seal eBay
35-10004Thermostat, 169°F/76°C1Thermostat eBay
35-11000Thermostat, 180°F/82°C1Thermostat Amazon eBay
B5009Engine Coolant Level Alarm SwitchSensor Amazon eBay
B5010Engine Coolant Level Information SwitchSensor Amazon eBay
B5101Engine Oil Pressure SensorSensor Amazon eBay
B5102Exhaust Manifold Pressure SensorSensor Amazon eBay
B5103EGR Flow SensorSensor Amazon eBay
B5104Manifold Air Pressure SensorSensor Amazon eBay
B5105Crankcase Pressure SensorSensor Amazon eBay
B5107Low Pressure Fuel Pressure SensorSensor Amazon eBay
B5108Engine Coolant Pressure SensorSensor Amazon eBay
B5113Fuel Rail Pressure Sensor2Sensor Amazon eBay
B5200Fixed Turbocharger Compressor Outlet Temperature SensorSensor FridayParts $9.50
B5205Charge Air Cooler Outlet Temperature SensorSensor Amazon eBay
B5206Manifold Air Temperature SensorSensor Amazon eBay
B5207EGR Temperature SensorSensor Amazon eBay $65.09
B5208Engine Coolant Temperature SensorSensor Amazon eBay
B5209Fuel Temperature SensorSensor Amazon eBay
B5300VGT Speed SensorSensor Amazon eBay
B5302Camshaft Position SensorSensor Amazon eBay
B5500Intake Air SensorSensor Amazon eBay
B5600Water-In-Fuel SensorSensor Amazon eBay
R116516Engine Cylinder Head Gasket1Gasket eBay $43.99 FridayParts $43.15
R123226Gasket, Water By-pass Tube2Gasket Amazon eBay $16.80 FridayParts $17.80
R123345Gasket, Thermostat Housing1Gasket eBay $17.10
R123354Gasket, Engine Oil Pan1Gasket Amazon eBay FridayParts $34.99
R123417Gasket, Water Pump1Gasket Amazon eBay $20.00
R123437Drive Belt, LP-MP668T-H (with turbo)1Belt eBay $41.05 FridayParts $47.99
R123439Drive Belt, LP-MP445D (non-turbo)1Belt Amazon eBay $425.00 FridayParts $49.99
R123457Drive Belt LP-MP668T-H (with turbo, formerly #R123464)1Belt Amazon eBay $34.95
R123464Drive Belt, LP668D (non-turbo, replaces R123463)1Belt eBay $59.00
R123501Gasket1Gasket eBay $19.95 FridayParts $29.99
R123504Gasket, Remote Oil Filter Adapter1Gasket eBay $3.00
R123525Gasket1Gasket eBay $18.33
R123543Gasket, Rocker Arm Cover1Gasket Amazon eBay
R123570Gasket1Gasket Amazon eBay $9.99
R123572Gasket1Gasket Amazon eBay $19.48
R128455Hose, Radiator Inlet1Hose Amazon eBay FridayParts $89.99
R128456Hose, Radiator Outlet1Hose Amazon eBay $39.99
R135896Gasket1Gasket Amazon eBay $12.99
R500374Gasket1Gasket eBay $11.99
R53108Gasket, Starting Motor1Gasket eBay $14.48
R89944O-Ring1Seal Amazon eBay $8.97
R90658Gasket, Exhaust Manifold6Gasket Amazon eBay $21.99
RE16553Seal Kit, Fuel Filter1Seal eBay
RE44574Seal1Seal Amazon eBay $39.63
RE48786Fuel Injector (with turbocharger, includes keys 2-3)1Injector Amazon eBay $44.95 FridayParts $105.00
RE500734Coolant Pump, Aluminum1Pump eBay $48.99
RE505929Injection Pump, 12 Volt Isolated Ground1Pump eBay
RE505980Coolant Pump, Cast Iron1Pump eBay FridayParts $78.00
RE518097Belt Tensioner1Belt eBay $54.10 FridayParts $48.36
RE59810Seal Kit, Front Oil Seal1Seal Amazon eBay FridayParts $22.89
RE60062Fuel Injector (without turbocharger, includes keys 2-3)1Injector Amazon eBay $139.40 SinoCMP $99.00 FridayParts $109.25
RE68345Fuel Pump (includes keys 2-5)1Pump eBay FridayParts $34.50
RE69791XDInjection Pump, 12 Volt Standard Ground1Pump eBay
RE69792XDInjection Pump, 24 Volt Standard Ground1Pump eBay
SP10Change secondary fuel filter1Fuel filter Amazon
SP12Check fuel injection pump1Fuel injection pump Amazon eBay FridayParts $189.99
SP13Check turbocharger boost pressure1Fuel filter Amazon eBay
SP18Check and clean gear oil cooler1Batteries Amazon eBay $135.00 NAPA $58.83
SP19Change impeller in raw water pump1Impeller Amazon eBay
Y5004Low-Pressure Fuel PumpPump Amazon eBay
Y5020DEF Dosing InjectorInjector Amazon eBay
Y5021Fuel Injector HarnessInjector Amazon eBay $6.99
Y5501Low-Pressure Fuel PumpPump Amazon eBay
25-19511Wear Plate1Service part / kit eBay
54-51006Drain Valve, Metal1Service part / kit eBay
A5507DEF Tank Header Assembly ConnectorService part / kit Amazon eBay
B5204SCR Temperature ModuleService part / kit Amazon eBay
B5212Temperature ModuleService part / kit Amazon eBay
B5301Crankshaft Position Sensor2Service part / kit Amazon eBay
F5000FuseService part / kit Amazon eBay
K5803Cold Start Aid Relay1Service part / kit Amazon eBay
RE509813Repair Kit1Service part / kit eBay
SP15Check and flush cooling system1Service part / kit Amazon eBay NAPA $2755.74
SP23Check state of charge of batteries1Service part / kit Amazon eBay NAPA $22.66
X5007Remote switch jumperService part / kit Amazon eBay
X5401Air throttle connectorService part / kit Amazon eBay
Y5014Fan Solenoid - IncreaseService part / kit Amazon eBay $41.99
Y5015Fan Solenoid - DecreaseService part / kit Amazon eBay
Y5018Ether Control SolenoidService part / kit Amazon eBay
Y5022Pressure Control Valve 1 (PCV)Service part / kit Amazon eBay
Y5023Pressure Control Valve (PCV) 2Service part / kit Amazon eBay
Y5024Pressure Relief ValveService part / kit Amazon eBay
Y5400EGR ValveService part / kit Amazon eBay
Y5401Air Throttle ActuatorService part / kit Amazon eBay
Y5500VGT Actuator42Service part / kit Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Available documents

Spec sheet — LP668D (Northern Lights)Operator's manual — OLP (Northern Lights)Parts manual — P668PT (Northern Lights)Parts manual — filter chart guide (Northern Lights)

This page was generated from the 4 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.

Full service, cheapest listings

Priced items from this model's own parts manual.

Fuel filter 24-51005$17.99
Oil filter 24-01002$24.44
Belt R123437$41.05
3 priced items$83.48
Other sets with this engine