Northern Lights O843K User manual

OPERATOR’S
MANUAL
OPERATOR’S
MANUAL
O843K
For Models
M843JK, M843NK, NL843NK

Diesel engine exhaust and some of its constituents
are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
— CALIFORNIA —
Proposition 65 Warning:
Northern Lights
4420 14th Avenue N.W.
P.O. Box 70543
Seattle, WA 98107
Tel: [phone]
Fax: [phone]
Copyright ©2003 Alaska Diesel Electric, Inc.
All rights reserved. Northern Lights™, and
the Northern Lights logo are trademarks of
Alaska Diesel Electric, Inc.
Printed in U.S.A.
PART NO.: O843K 05/03

O843K 05/03
Read this operator's manual thoroughly before starting to operate your equipment.
This manual contains information you will need to run and service your new unit.
1
Proprietary Information
This publication is the property of Alaska Diesel Electric, Inc.
It may not be reproduced in whole or in part without the written permission of Alaska Diesel Electric, Inc.
© Alaska Diesel Electric, Inc. All rights reserved. Litho U.S.A. Publication number O843K 05/03
OPERATOR'S MANUAL
for Models
M843JK, M843NK, and NL843NK
Table of Contents
INTRODUCTION ......................................................2
Models Included ...................................................2
Model Numbers....................................................2
Serial Numbers .....................................................3
WARRANTY ..............................................................3
SAFETY RULES .......................................................3
COMPONENT LOCATIONS
M843JK and M843NK Marine Generator ...........4
NL843NK Industrial Generator ...........................5
CONTROL PANELS
Northern Lights Generator Sets......................6 - 7
OPERATING PROCEDURES
Break-in Period ....................................................8
Before Starting .....................................................8
Starting .................................................................8
Operating ..............................................................8
Stopping ...............................................................8
Shutdowns and Alarms.........................................9
Spare Parts............................................................9
SERVICING SCHEDULE CHART .............. 10 - 11
SERVICING
Lubrication - General ........................................ 12
Checking Oil ..................................................... 12
Oil Changes ....................................................... 12
Changing Oil Filter............................................ 12
Air Filter ............................................................ 13
SERVICING (continued)
V-Belts .............................................................. 13
Retightening Cylinder Head Bolts .................... 13
Valve Clearances............................................... 13
Fuels - General .................................................. 14
Fuel Filters......................................................... 14
Bleeding the Fuel System.................................. 15
Injector Service ......................................... 16 - 17
Injection Pump .................................................. 17
Cooling System - General ................................. 17
Cooling System Flushing .................................. 18
Heat Exchanger (Marine) .................................. 18
Raw Water Pump .............................................. 18
Generator Ends .................................................. 18
Electrical System - General............................... 18
Glow Plugs ........................................................ 19
Booster Batteries ............................................... 19
Battery Care....................................................... 19
PTO Care........................................................... 19
Winterizing / Out-of-Service............................. 19
Exhaust Elbow................................................... 19
TROUBLESHOOTING
Electrical............................................................ 20
Engine........................................................ 21 - 23
DATA SHEETS
M843JK ............................................................. 24
M843NK............................................................ 25
WIRING DIAGRAMS
DC Electrical ............................................. 26 - 27

O843K 05/03
Introduction
2
Unit Identification
Servicing of marine engines and generator sets presents
unique problems. In many cases boats cannot be moved
to a repair facility. Marine engines cannot be compared
to the servicing of automobiles, trucks or even farm
equipment. Failures often occur in remote areas far
from competent assistance. Marine engines are taxed
far more severely than auto or truck engines; therefore,
maintenance schedules must be adhered to more
strictly.
Failures can begin with minor problems that are
overlooked and become amplified when not corrected
during routine maintenance.
As operator, it is your obligation to learn about your
equipment and its proper maintenance. This is not a
comprehensive technical service manual. Nor will it
make the reader into an expert mechanic. Its aim is to
aid you in maintaining your unit properly.
J / K
MODELS INCLUDED
This manual covers the operating instructions for:
M843JK marine generator sets,
M843NK marine generator sets, and
NL843NK industrial generator sets.
Fill in the model number of your unit in the blank space provided.
This will give you a reference whenever service or maintenance is required:
Additional letter
designates series
within model number
++
Northern Lights marine diesel generator set with
a J-series 843 engine and a PX-300K generator end
with an AVR.
M / NL 843
=
M843JK
Northern Lights marine diesel generator set with
an N-series 843 engine and a PX-300K generator
end.
=
M843NK
Northern Lights industrial generator set with an N-
series 843 engine, PX-300K generator with an AVR,
and a radiator.
=NL843NK
Model number of engine block
Bore Cylinders
84 mm 3
M - Northern Lights marine generator set
NL - Northern Lights industrial generator set
Model Numbers
Model numbers give the unit's application, block model, aspiration, and RPM:
My Northern Lights generator set MODEL number is:

O843K 05/03
Serial Numbers
3
Safety Rules
CAUTION: This symbol is used throughout
this book to alert you to possible danger areas.
Please take special notice of these sections.
A warranty registration certificate is supplied
with your set. It entitles the original purchaser of our
equipment to a warranty covering material
or assembly faults. The extent of coverage is described
in the Limited Warranty Statement. We recommend
that you study the statement carefully.
NOTE: If the warranty is to apply, the servicing
instructions outlined in this manual must be
followed. If further information is needed, please
contact an authorized dealer or the factory.
CAUTION: Accident reports show that careless use of engines causes a high percentage of accidents.
You can avoid accidents by observing these safety rules. Study these rules carefully and enforce them on the job.
• Never leave engine without proper security.
• Turn the coolant tank cap slowly to relieve pressure
before removing. Add coolant only when the
engine is stopped and cool.
• Mount a fire extinguisher near engine.
• Always disconnect the battery ground strap before
making adjustments.
• Operate engines in properly ventilated areas.
• Keep trash and other objects away from engine.
• Escaping fluids under pressure can penetrate your
skin. Use a piece of cardboard or wood, not your
hands, to search for leaks.
• Avoid wearing loose clothing without a belt when
working around engines.
• Do not oil or grease engine while it is running.
• Use caution in handling fuel. Never refuel a hot or
running engine. Do not smoke while filling fuel
tank or servicing fuel system.
Your set has three serial numbers: ➀an engine number stamped
on the block, ➁a generator plate, and ➂a generator set plate.
Use the serial number on the generator set plate when ordering parts
or in correspondence. The generator set plate is found on the service
side of the generator and resembles the drawing in Figure 1.
Fill in the serial number of
your unit in the box provided.
Figure 1: Generator set serial number plate.
Warranty
•Keep your hands, feet, hair and clothing away from
power-driven parts.
•Check for any loose electrical connections or faulty
wiring.
•Engines should be operated only by
knowledgeable, qualified personnel.
•Look completely around engine to make sure that
everything is clear before starting.
•Do not operate an engine that isn't in proper
working order. If an unsafe operating condition is
noted, tag the set and control panel so others will
also know about the problem.
•Provide first aid kits.
My Northern Lights generator set SERIAL number is:

O843K 05/03
1. DC Circuit Breaker
2. AC Circuit Breaker for AVR
3. Fuel Filter
4. Air Filter (inside Manifold)
5. Intake Manifold
6. Fuel Lift Pump
7. Oil Fill (2)
8. Crankcase Vent
9. Fuel Injector
10. Coolant Fill
11. Heat Exchanger End Cap
12. Injection Pump
13. Seawater Pump
14. Freshwater Block Drain
15. Fuel Inlet & Return
16. Oil Filter
17. Oil Dipstick
18. Oil Drain
19. Control Panel Plug-In
20. Generator Set Plate
21. Expansion Tank
Marine Generator Component Locations
4
▼
Non-Service Side
22. Wet Exhaust Elbow
23. Junction Box
24. Starter
25. Vibration Mount
26. DC Alternator
Service Side
▼
Figure 2: M843JK, M843NK, service and non-service views

O843K 05/03
8. Lube Oil Drain
9. AC Circuit Breaker
11. Secondary Fuel Filter
12. Crankcase Vent
13. Lube Oil Fill
14. Coolant Fill
15. Injection Pump
16. Fuel Inlet and Return
17. Oil Filter
18. Fuel Lift Pump
19. Block Water Drain
20. Dipstick
1. DC Alternator
2. Exhaust Outlet
3. Air Filter
4. Starter
5. DC Circuit Breaker
6. Generator Junction Box
7. Starter
Industrial Generator Set Component Locations
5
Non-Service Side
▼
Service Side
▼
Figure 3: NL843NK, service and non-service views

O843K 05/03
Control Panels
6
Figure 4-B: Series 3 Generator Control Panel
Figure 4-A: Series 1-B Generator Control Panel
Figure 4-C: Series 4 Generator Control Panel
1. SHUTDOWN BYPASS-PREHEAT SWITCH
Two functions are built into this switch: the preheating
of the engine, and bypassing of the engine safety
shutdown circuit. Hold switch in the ON position
10 - 20 seconds before starting the engine, and
continue holding on during engine cranking. Release
the switch as soon as the engine is running. Holding
the switch on too long can burn out the heater element.
2. ENGINE CONTROL SWITCH
To start the engine, hold this switch in the START
position until the engine is running.
NOTE: Excessive cranking of marine sets equipped
with water lift muffler systems can cause engine
damage. See page 10.
After the engine starts, release the switch and it will
return to RUN position. To stop the engine, hold the
switch in the STOP position until the engine has
completely stopped.
NOTE: The rocker switch is used on Series 1 panels
only, and has a light that glows when the set is running.
3. HOUR METER
Keeps track of engine running time.
4. OIL PRESSURE GAUGE
Shows the oil pressure in the engine lubricating system.
5. ENGINE TEMPERATURE GAUGE
Registers the temperature of the engine coolant.
6. D.C. VOLTMETER OR AMMETER
When the engine is stopped, the voltmeter indicates the
condition of the battery. When the engine is running, the
voltmeter indicates the voltage output of the alternator.
For Series 4 Control Panels Only:
7. A.C. VOLTMETER
Shows the generator output voltage.
8. FREQUENCY METER (Hertz)
The frequency meter indicates alternating current
frequency: 60 Hz (1800 RPM), or 50 Hz (1500 RPM).
9. AMMETER/VOLTMETER
SELECTOR SWITCH
Used to check voltage and current of each phase.
10. A.C. AMMETER
Shows the generator load on each phase. The phase is
selected with the Ammeter Selector switch (Item 9).

O843K 05/03
7
Control Panels
6. STATUS INDICATOR PANEL
Engine monitoring alarms and lamps for monitoring
engine functions.
7. ALARM LAMP TEST AND RESET BUTTON
Press UP to test the indicator lights and press DOWN
to reset the alarm.
8. AC VOLTAGE ADJUSTMENT RHEOSTAT
Voltage has been set at the factory and should only be
adjusted by factory-trained personnel.
9. AMMETER SELECTOR SWITCH
Used to check each phase for load condition.
NOTE: Always leave this switch in the ON position
while the unit is running.
10. FREQUENCY METER (HERTZ)
The frequency meter indicates alternator current
frequency: 60 Hz (1200 or 1800 RPM), or 50 Hz
(1500 RPM).
11. A.C. VOLTMETER
Shows the generator output voltage.
12. A.C. AMMETER
Shows the generator load on each phase. The phase is
selected with the Ammeter Selector switch.
Figure 5: Series 7.0 through Series 7.6 Generator
Control Panels
1. SHUTDOWN BYPASS SWITCH
Manual Start Panels
(S-7.1 and S-7.3)
Hold the switch in the START position until the engine is
running
NOTE: Excessive cranking may cause engine damage.
After the engine starts, release the switch and it will return
to the RUN position. To stop the engine, hold the switch in
the STOP position.
Auto Start Panels
(S-7.0, S-7.2, S-7.4, S-7.5, and S-7.6)
After the engine starts, release the switch and it will return
to the RUN position. To stop the engine, hold the switch in
the STOP position.
2. OIL PRESSURE GAUGE
Shows the oil pressure in the engine lubricating system.
3. HOUR METER
Keeps track of engine running time.
4. ENGINE TEMPERATURE GAUGE
Registers the temperature of the coolant.
5. DC VOLTMETER
When the engine is running, the voltmeter indicates the
voltage output of the alternator.

O843K 05/03
8
BREAK-IN PERIOD
1. The first 100 hours on a new or reconditioned
engine are critical to its life and performance.
2. Frequently check the engine temperature and oil
pressure gauges (sets with Series 3 or 4 panels).
3. Oil consumption is greater during break-in as
piston rings take time to seat.
4. Break-In Oil Changes: Change engine oil and
filter at 50 hours. Change oil and filter again at
100 hours (consult Lubricants section for oil
recommendation).
5. Retighten head bolts at 50 hours (see page 13).
Operating Instructions:
Maintain at least a 75% load on your generator
set for the first 100 hours. If this is not possible,
maintain no less than a 50% load to ensure proper
seating of the piston rings. Vary the load to help
seat the rings.
BEFORE STARTING
1. Check the water level by removing the pressure
cap from the expansion tank or radiator. In order to
give the cooling water an opportunity to expand, the
level should be about 1 in. (2.5 cm) below the filler
cap sealing surface when the engine is cold.
CAUTION: Use protective clothing and open
the filler cap carefully when the engine is warm
to prevent burns.
2. Check the oil level in the crankcase with the
dipstick. The oil level must be in the waffled area on
the stick. Never allow the level to go below this area.
Always add the same viscosity of oil as is already in
the crankcase.
3. Check the fuel tank level and open any fuel valves.
4. Marine Sets: close the sea-cock; check, clean, and
reassemble the sea strainer and reopen the sea-cock.
5. Marine Sets: place the battery switch in the ON
position.
6. NOTE: The battery switch must always be kept
ON while the engine is running. If the switch is
turned OFF while the engine is running, the
battery charging regulator could be ruined.
STARTING
1. Hold the Shutdown Bypass-Preheat switch in the
ON position for 10 to 20 seconds before starting a
cold engine. Holding the switch too long can burn
out the glow plugs. This step is not necessary if the
engine is already warm.
2. While holding the Shutdown Bypass-Preheat switch
in the ON position, push the Engine Control switch
to the START position.
3. As soon as the engine starts, release both switches. Do not
crank the starter for more than 20 seconds consecutively.
If the engine fails to start with the first attempt, be sure
that it has stopped completely before re-engaging.
6. NOTE: Excessive cranking of the starter on Marine
sets equipped with a water lift muffler can cause
engine damage. If the engine does not start after three
20-second cranks, remove the impeller from the raw
water pump. This will prevent the muffler from filling
with water and backfilling the exhaust line and engine.
Once the engine starts, shut it off immediately and
re-install the impeller. Re-start the engine and check
the exhaust overboard outlet for gushes of water.
OPERATING
1. Units with Series 3 and Series 4 Control Panels:
check gauges often. Oil pressure must be above 15
PSI. The D.C. voltmeter should read between 11 and
15 volts at 80°F (25°C) ambient temperature. The
water temperature gauge on Marine sets must be
below 200°F (94°C); on Industrial units the water
temperature gauge must be below 2250F (1070C).
Check the A.C. voltage and frequency meters (Series
4 panel). If the gauges deviate from normal levels,
shut down the generator set and investigate.
2. Let the unit run unloaded for a three to five minute
warm-up period.
3. Apply electrical load.
STOPPING
1. Remove electrical load from the generator set.
2. Run the engine for a 3 to 5 minute cool down period.
3. Hold the Engine Control switch to the STOP
position until the engine comes to a complete stop.
4. Marine Sets: shut off the seacock, fuel valve, and
battery switch.
Operating Procedures

O843K 05/03
9
SHUTDOWNS AND ALARMS
1. Your unit is fitted with a system to protect it from
high water temperature or low oil pressure.
a. Generator sets have shutdown systems to stop the
engine. They have no warning horns.
b. Other alarms and shutdowns are available as
optional equipment.
NOTE: Do not rely on your warning to the
exclusion of careful gauge monitoring. Watching
your gauges can prevent damage to the unit and
dangerous power losses.
2. Do the following when your warning or shutdown
system is activated:
a. Check the temperature gauge.
Marine sets: If above 205°F (96°C), shut off the
engine immediately.
Industrial sets: If above 2300F (1100C) shut off
the engine immediately.
b. Use the Trouble Shooting Guide on page 22 to
isolate the cause of the overheat.
CAUTION: Do not remove the water fill
cap of an overheated engine. Escaping high
temperature steam can cause severe burns.
Allow the engine to cool and then remove the
cap slowly using protective clothing.
d. Make repairs. Restart your Marine set after the
temperature gauge registers below 200°F (94°C).
e. Watch the temperature gauge regularly and
turn off the unit if the temperature rises
above 205°F (96°C) on Marine units.
Repeat troubleshooting.
3. If shutdown is activated and the temperature gauge
shows temperature within normal temperature range:
a. Check the engine crankcase oil level.
b. 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.
c. If the oil level is normal, DO NOT restart the
engine. Call your dealer for assistance.
SPARE PARTS
1. ADE recommends that you keep the following spare
parts on hand for field service. The parts are
available from your local Northern Lights dealer.
Some marine models already have “On-Board-Kits,”
a handy box that contains the most common parts
you will need.
2. All owners should have the following spares:
a. Primary and secondary fuel filter elements
b. Oil filters
c. Air filter
d. Alternator belt
e. Thermostat and gaskets
f. Seawater pump impeller & gaskets (marine only)
g. Glow plug
h. Injector and washer
3. If your set is operating a long distance from a
servicing dealer, add the following:
a. Complete set of injectors
b. Copper washers for injector change
c. Complete set of glow plugs
d. Fuel lift pump
Operating Procedures

O843K 05/03
The Servicing Schedule Chart below shows the service schedule required for proper maintenance of your generator set.
More detailed coverage of each Service Point (SP) is listed on the page noted in the ‘page’column.
DAILY:
SP1 Check oil level in engine
SP7 Check primary fuel filter
SP13 Check cooling water level
Check sea strainer (marine only)
Check raw water pump for leaks
AFTER FIRST 50 HOURS:
SP2/3 Change engine oil and filter
SP5 Check V-belt tension
SP6 Adjust valves
SP18 Check electrolyte in batteries
Retighten head bolts (see page 11)
EVERY 50 HOURS:
SP5 Check V-belt tension
SP18 Check electrolyte in batteries
EVERY 100 HOURS:
SP16 Check and clean radiator (industrial only)
EVERY 200 HOURS:
SP2/3 Change engine oil and filter
SP4 Check air cleaner
SP8 Change primary fuel filter element
SP9 Change secondary fuel filter
EVERY 600 HOURS:
SP6 Check valve clearances
SP11 Check injectors
SP14 Check and flush cooling system
SP17 Change impeller (marine only)
SP19 Check state of charge of batteries
EVERY 2400 HOURS:
SP12 Check fuel injection pump
SP15 Check and clean heat exchanger (marine only)
1) Perform all maintenance once a year even if hour level has not been reached.
2) Consult manufacturer's maintenance schedule, note on chart.
3) Whenever necessary.
4) More often if necessary.
5) After first 50 hours.
Servicing Schedule Chart
10
SERVICE 50 100 200 600 2400
POINT PAGE OPERATION DAILY Hours Hours Hours Hours Hours
ENGINE:
SP1 8 & 12 Check oil level ●
SP2 12 Change engine oil 1) 5) ●
SP3 12 Change lube oil filters 1) 5) ●
SP4 12 Check air cleaner 1) 4) ●
SP5 12 Check V-belt tension 1) 4) ●
SP6 13 Check valve clearances 1) 2) 5) ●
FUEL SYSTEM:
SP7 14 Check primary filter (Racor) 2) 3) ●
SP8 14 Change primary filter element (Racor) 2) 3) ●
SP9 14 Change secondary fuel filter 1) 3) ●
SP10 15 Bleed the fuel system 3)
SP11 16 - 17 Check injectors 1) 3) ●
SP12 17 Check fuel injection pump ●
COOLING SYSTEM:
SP13 8 & 17 Check cooling water level ●
SP14 17 - 18 Check and flush cooling system ●
SP15 18 Check and clean heat exchanger (Marine) ●
SP16 - Check and clean radiator fins (Industrial) ●
SP17 18 Change impeller in raw water pump 1) 3) ●
SP21 Inspect condition of exhaust elbow 4) ●
ELECTRICAL SYSTEM:
SP18 19 Check electrolyte level in batteries 1) 4) ●
SP19 19 Check condition of batteries with hydrometer 1) 4) ●
DRIVEN EQUIPMENT:
SP20 19 Clutch and PTO service (M843NK only) 2)
OUT OF SERVICE:
SP21 19 Winterizing or out-of-service 3)

O843K 05/03
50 HOURS
SP5 Check V-belt tension
SP18 Check electrolyte in batteries
100 HOURS
SP3 Change lubricating oil filters
SP4 Check air cleaner
SP16 Check and clean radiator
EVERY 200 HOURS
SP2 Change engine oil and filter
SP8 Change primary filter element (Racor)
SP9 Change secondary fuel filter
SP21 Inspect condition of exhaust elbow
EVERY 600 HOURS
SP6 Check valve clearances
SP11 Check injectors
SP14 Check and flush cooling system
SP17 Change impeller in raw water pump
SP19 Check condition of batteries with hydrometer
2400 HOURS
SP12 Check fuel injection pump
SP15 Check and clean heat exchanger
Service
Point HOURS/DATE
Service Record
OPERATION
11

O843K 05/03
Servicing
LUBRICATION - GENERAL
1. Use only clean, high quality lubricants stored in
clean containers in a protected area.
2. These lubricants are acceptable:
a. API Service CC/CD/CE single viscosity oils.
b. API Service CC/CD/SF multi-viscosity oils.
3. Use the proper weight oil for your average operation
temperature.
Figure 6: Lube Oils
4. Some increase in oil consumption may be expected
when SAE 5W and SAE 5-20W oils are used. Check
oil level frequently.
5. Never put additives or flushing oil in crankcase.
SP1. CHECKING OIL LEVEL
1. Check the oil level in the crankcase with the
dipstick. The oil level must be in the waffled area
on the stick. Never allow the level to go below this
area. Follow the lubrication recommendations above.
SP2. OIL CHANGES
1. The set is delivered with special break-in oil.
Change the engine oil and oil filter after 50 hours
of operation. Use Service CC 30 weight oil during
the first 100 hours.
2. Change the oil and filter again at 100 hours using the
oil recommended in the above diagram. After this,
change oil and filter every 200 hours.
3. During intermittent cold weather operation, change
oil every 100 hours or six weeks, whichever comes
first.
4. Change oil at the end of each season and the
beginning of each season.
5. Change oil when engine is warm.
6. Dispose of waste oil in an approved manner.
7. Never use a flushing oil.
8. Loosen the clamp on the oil change tube. Remove
cap. Drain oil. Replace the cap and tube.
9. Refill engine with recommended oil for the season.
10. Engine capacity with new oil filter is:
843JK and 843NK – 5.8 quarts (5.5 liters)
SP3. CHANGING LUBE OIL FILTER
1. Change the lube oil filter every 200 hours.
2. Use a filter wrench to remove old filter. Dispose of
filter in approved manner.
3. Make sure the gasket from the old filter is removed
and discarded. Clean mount face.
4. Spread a thin film of engine oil on the rubber gasket
on the new filter and screw it on nipple until gasket
meets the sealing surface.
5. Using hands only –no wrench –tighten filter
one-half turn farther. Overtightening can do
damage to filter housing.
6. Fill engine with recommended oil. Start engine and
check for leakage. Stop engine, wait 3 minutes, and
check oil level. Add additional oil if necessary.
7. Oil filter part number is:
843JK and 843NK – #24-03100
Air Single Multi-
Temperature Viscosity Viscosity
Above 32°FSAE 30W SAE 15-40W
(0°C)
-10 to 32°FSAE 10W SAE 10-30W
(-23 to 0°C)
Below -10°FSAE 5W SAE 5-20W
(-23°C)
12

O843K 05/03
SP4. AIR CLEANER
1. Inspect air cleaner every 200 hours. In dusty
conditions, check more often.
2. Marine sets: if dirty, wash element in soapy water.
Rinse and dry thoroughly before re-installing.
Replace if necessary. Part numbers are:
M843JK and M843NK –#24-23100
3. Industrial sets: the element cannot be cleaned.
Replace it when necessary. Part number is:
NL843NK –#314531127
4. NOTE: Make absolutely sure no impurities enter
the engine while changing the element. Do NOT
run the engine with the air cleaner removed.
SP5. V-BELTS
1. Check the tension and wear on the V-belt after
every 50 hours.
2. Use your thumb to press on the belt at the midpoint
between the crankshaft and alternator pulleys. The
tension is correct if the belt can be depressed about
3/16 in. (5 mm).
RETIGHTENING CYLINDER HEAD BOLTS
1. Tighten bolts when the engine is cold.
2. Loosen the nuts and remove rocker arm cover.
3. Tighten head bolts with a torque wrench in the order
shown in figures below. Tighten bolts evenly in 2 or
3 passes, ending at the specified torque in final pass.
843JK & 843NK: 60 - 64 ft/lbs (9.0 - 9.5 kg/m)
Servicing
Figure 7: 843N Head Torque Sequence
Figure 8: Valve Adjustment
SP6. VALVE CLEARANCES
1. Adjust valve clearance after first 50 hours of
operation and every 600 hours thereafter.
2. Valve adjustments should be done after the cylinder
head bolts have been re-tightened. Engine should be
cold and NOT running.
3. Watch the valves while turning the engine over by
hand. Turn until the inlet valve starts to open and the
exhaust valve starts to close (the valves are rocking).
Then turn the crankshaft one more full turn and
adjust the clearance on both valves for this cylinder.
4. Loosen the lock nut and adjust the clearance
between the rocker arm and valve guide of both the
intake and exhaust valves with the adjustment screw
(Figure 8). Clearance on both intake and exhaust
valves should be 0.008 in. (0.2 mm).
5. Repeat steps 3 and 4 for each cylinder. Each set of
valves must be adjusted individually.
6. Replace the rocker arm cover. Tighten cover nuts to
5 - 8 ft/lbs (0.8 - 2.3 kg/m).
13
Valve Adjustment Screw
Rocker Arm
0.008 in.
0.200 mm.

O843K 05/03
14
Servicing
FUELS - GENERAL
1. Use only clean, high quality fuels of the following
specifications, as defined by ASTM designation
D975 for diesel fuels:
a. Use grade no. 2 diesel at ambient temperatures
above freezing 32°F (0°C).
b. Use grade no. 1 at ambient temperatures below
freezing and for all temperatures at an altitude of
above 5,500 ft. (1500 meters).
2. Use fuel having less that 1% sulphur (preferably less
that 0.5%).
3. The cetane number should be a minimum of 45.
4. DO NOT use these unsuitable grades of fuel:
a. Domestic heating oils, all types.
b. Class B engine.
c. Class D domestic fuels.
d. Class E, F, G or H industrial or marine fuels.
e. ASTM-D975-60T No. 4-D and higher number
fuels.
5. Storing fuel:
a. Keep dirt, scale, water, and other foreign matter
out of fuel.
b. Avoid storing fuel for long periods of time.
c. Fill the fuel tank at the end of each day’s
operation. This will reduce condensation and
possible biological contamination.
d. If biological contamination is detected or
suspected, contact your dealer for assistance.
SP7-9. FUEL FILTERS
1. Your generator set should have a primary fuel filter
installed. We recommend the Racor brand of fuel
filter-water separators.
a. Check the primary fuel filter daily as
recommended by the filter manufacturer.
Empty the collection bowl as necessary.
b. Change the element as often as necessary or
every 200 hours.
c. If the bowl fills with water, change the primary
and secondary element immediately.
2. Change secondary fuel filter every 200 hours.
NOTE: The fuel filter on the engine is considered the
“secondary fuel filter.”
a. Remove the spin-on filter by turning it
counterclockwise with a filter wrench. Fill the
new cartridge with fuel and install it after
applying engine oil to gasket surface. Screw on
until the gasket surface comes into contact with
sealing surface of filter base. Then, tighten it
two-thirds of a turn by hand. Do not overtighten.
b. Fuel filter part numbers are:
843JK and 843NK –#130336020

O843K 05/03
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Servicing
SP10. BLEEDING THE FUEL SYSTEM
CAUTION: Escaping diesel fuel under pressure can penetrate skin causing serious personal injury.
Before disconnecting lines be sure to relieve all pressure. Before applying pressure, be sure all connections
are tight and lines, pipes and hoses aren't damaged. Fuel escaping from a very small hole can be almost
invisible. Use a piece of cardboard or wood, rather than hands, to search for suspected leaks. If injured by
escaping fuel, see a doctor at once. Serious infection or reaction can develop if proper medical treatment
isn't administered immediately.
Figure 9: NL843NK Fuel System.
1. The fuel system is self-bleeding. However, any
system may need manual bleeding when:
a. A new fuel filter is installed;
b. The engine has run out of fuel;
c. The fuel lines, injection pump or any other fuel
system component has been removed and
installed.
2. Loosen bleed bolt “A”(Figure 9) on top of the filter.
Pump hand primer “B”on fuel lift pump until pure
fuel (no bubbles) escapes from bleed bolt “A”.
Tighten bleed screw “A”.
3. Loosen bleed screw “C”. Pump hand primer “B”
until pure fuel (no bubbles) escapes. Then tighten
bleed screw “C”.
4. If the engine does not start after the above bleeding
process, loosen a fuel line at the injector while
cranking the engine with the starter motor until pure
fuel escapes. Then tighten the connection. Do each
line one-at-a-time.
5. After the engine has started, use a piece of cardboard
to look for fuel leaks.

O843K 05/03
Figure 10: Remove delivery line flare nuts.
Figure 11: Remove delivery lines.
Figure 12: Cover lines, inlets and injection pump outlets.
Figure 14: Remove return line.
Figure 15: Unscrew injector.
Figure 16: Remove and replace copper sealing washer.
Figure 17: Reinstall injector. Torque to proper tightness.
Servicing
16
Figure 13: Remove return line nuts.

O843K 05/03
SP11. INJECTOR SERVICE
1. Injectors should be checked every 600 hours. Check
should be made by a Northern Lights dealer or local
injection repair station.
CAUTION: Escaping diesel fuel under pressure
can have sufficient force to penetrate the skin
causing serious personal injury. If injured by
escaping diesel fuel, see a doctor at once.
2. Injector removal:
a. Clean loose dirt from around the injectors and
the fuel lines.
b. Relieve high pressure in the fuel lines by
loosening the delivery line flare nuts at each
injector (Figure 10).
c. Remove delivery lines by disconnecting from
injectors and injection pump (Figure 11). Remove
all lines as an assembly; do not remove the spacers.
Cover the ends of the lines, the injector inlets and
injection pump outlets to keep dirt out (Figure 12).
d. Remove the return line retaining bolts (Figure 13).
Remove the return line (Figure 14).
e. Unscrew and remove the injectors (Figure 15).
NOTE: Do not use pry bars to remove injectors
from cylinder head.
f. After removing the injectors, discard the copper
sealing washers from the injector hole in the head
(Figure 16). Cover holes to prevent dirt and debris
from entering the cylinders.
3. Injector installation:
a. Install a new copper sealing washer in each
injector hole (Figure 16).
b. Screw in injector and tighten to 44 - 51 ft/lbs
(6 to 7 kgm) (Figure 17).
NOTE: Overtightening can damage injector.
c. Install return line using a new sealing washer
below each connection. Tighten return line
retaining bolts to 22 - 30 ft/lbs.
d. Install delivery lines. Leave loose at injectors for
bleeding.
e. Crank engine to fill lines. Tighten lines at
injectors to 11-18 ft./lbs. Start engine and check
for leaks using a piece of paper or cardboard.
DO NOT use hand to check for leaks.
SP12. INJECTION PUMP
1. Since operating conditions may vary considerably, it
is difficult to give a definite interval for checking the
injection pump. But as a rule, pump settings,
maximum speed, idle speed and exhaust smoke
should be checked after every 2400 hours of
operation. Service of the fuel injection pump should
only be done if checks indicate pump malfunction.
2. Black smoke can be an indication of pump
malfunction. Before servicing the pump, check other
possible causes:
a. Check cleanliness of air filter.
b. Check valve clearances.
c. Clean and check injectors.
3. Any repair which involves disassembly of the
injection pump must be carried out by specially
trained mechanics with the proper tools and test
equipment.
NOTE: All warranties on the engine become null
and void if the injection pump seals are broken by
unauthorized persons.
COOLING SYSTEM - GENERAL
NOTE: Marine sets – be sure to close the sea-cock
before working on the engine cooling system.
CAUTION: The cooling water in the engine
reaches extremely high temperatures. You must
use extreme caution when working on hot
engines to avoid burns. Allow the engine to cool
before working on the cooling system. Open the
filler cap carefully, using protective clothing
when the engine is warm.
SP13. CHECK THE COOLANT LEVEL
1. Check the coolant level each day before starting the
engine. Check the water level by removing the
pressure cap from the expansion tank.
In order to give the cooling water an opportunity to
expand, the level should be about 1 in. (2.5 cm) below
the filler cap sealing surface when the engine is cold.
2. The pressure valve in the filler cap releases when the
pressure is approximately 7 PSI (0.5 bar). Use a cap
pressure tester to check cap if you suspect it is faulty.
Servicing
17

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Servicing
SP14. COOLING SYSTEM FLUSHING
1. Flush the cooling system every 600 hours or every
12 months, whichever comes first.
2. Marine sets:
a. Remove expansion tank cap and drain engine
block.
b. Open block drain cock. Remove hose from
bottom of heat exchanger tank.
c. Pour clean water into expansion tank until water
coming from drains is free of discoloration and
sediment. Let water drain completely. Close
drains and refill with recommended mixture.
3. Industrial sets:
Remove radiator cap and open drain cocks on
radiator and engine block. Pour clean water into
radiator until water coming from radiator is clear of
discoloration. Close the radiator drain and continue
flushing until water from engine drain is clear. Open
all drain cocks and drain completely. Close drain
cock and refill with recommended coolant mixture.
Clean fins on radiator.
3. Coolant Specifications (marine and industrial):
Use 50% distilled water / 50% ethylene glycol
antifreeze mix. Antifreeze mixture is recommended
as a good year-round coolant.
4. Check hoses and connections and repair any leakage.
SP15. HEAT EXCHANGER (Marine)
1. Clean the heat exchanger core once a year or after
2400 hours of operation.
2. Drain expansion tank and heat exchanger.
3. Remove heat exchanger end covers and remove
core.
4. Clean the inside of exchanger core tubes using
a metal rod. Flush, inspect and clean again if
necessary.
5. Reassemble. Fill the cooling system, start the engine
and check for leaks.
SP16. CLEAN RADIATOR (Industrial)
1. Remove debris from radiator fins daily.
2. In very dusty applications, clean the radiator with
compressed air or steam cleaner every 100 hours.
Clean in the reverse direction of the airflow.
SP17. RAW WATER PUMP (Marine)
1. Change the seawater pump impeller every 600
hours, or as needed.
2. Remove the pump end cover. Pry out the impeller
using needle-nose pliers or two screwdrivers.
Be sure you remove all pieces of failed impeller.
NOTE: Place some kind of protection under the
screwdrivers in order not to damage the pump
housing. If the impeller has broken into pieces,
remove front heat exchanger end cover and inspect
for impeller pieces. Clean inlet to heat exchanger
bundle and reassemble.
3. Clean the inside of the housing.
4. Press in the new impeller and place the sealing
washers in the outer end of the impeller center if this
has not already been done.
5. Replace the cover using a new gasket.
NOTE: Make sure that there is always an extra
impeller and cover gasket in reserve on board.
GENERATOR ENDS
The maintenance and operation recommendations
for the generator end are in a separate Owner’s
Manual. If you do not have one of these manuals,
contact your local Northern Lights dealer.
ELECTRICAL SYSTEM - GENERAL
1. Never switch battery switch off or break the circuit
between the alternator and batteries while the engine
is running. Regulator damage can result.
2. Do NOT reverse the polarity of battery cables when
installing the battery.
3. If welding on the unit, disconnect the regulator and
battery. Isolate the leads.
4. Disconnect the battery cables when servicing the
D.C. alternator.
5. Never test with a screwdriver, etc., against any
terminal to see if it emits sparks.
6. Do not polarize the alternator or regulator.
7. A D.C. circuit breaker protects your control panel
and wiring harness. It is located in the side of the
generator junction box.
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