Northern Lights Lugger OM773LW2 User manual

OM773LW2
For Models: M773LW and M773LW2
OPERATOR’SMANUAL
Marine Generators | Marine Diesel Engines | Land-Based Generators

Diesel engine exhaust and some of its constitu-
ents 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.
Seattle, WA 98107
Tel: [phone]
Fax: [phone]
Copyright ©2009 Northern Lights, Inc.
All rights reserved. Northern Lights™, and
the Northern Lights logo are trademarks of
Northern Lights, Inc.
Printed in U.S.A.
PART NO.: OM773LW2 10/09

OM773LW2 10/09
3
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.
OPERATOR'S MANUAL
for Models
M773LW and M773LW₂
INTRODUCTION ....................................................4
Models Included .................................................4
Model Numbers..................................................4
Serial Numbers ...................................................4
WARRANTY ............................................................5
SAFETY RULES.....................................................5
COMPONENT LOCATIONS
M773LW Marine Generators..............................6
M773LW2 Marine Generators............................7
PANELS
Northern Lights Generator Sets....................8 - 9
OPERATING PROCEDURES
Break-in Period................................................ 10
Before Starting................................................. 10
Starting............................................................. 10
Operating ......................................................... 10
Stopping........................................................... 10
Shutdowns and Alarms .....................................11
Spare Parts........................................................11
SERVICING SCHEDULE CHART.................... 12
SERVICING
Lubrication - General....................................... 14
Checking Oil.................................................... 14
SERVICING (CONTINUED)
Oil Changes ..................................................... 14
Changing Oil Filter.......................................... 14
Air Filter .......................................................... 15
V-Belts............................................................. 15
Valve Clearances.............................................. 15
Fuels - General................................................. 16
Fuel Filters....................................................... 16
Bleeding the Fuel System................................ 17
Injector Service........................................ 18 - 19
Injection Pump................................................. 19
Cooling System - General................................ 19
Cooling System Flushing................................. 20
Heat Exchanger ............................................... 20
Raw Water Pump ............................................. 20
Generator Ends ................................................ 20
Electrical System - General............................. 20
Glow Plugs....................................................... 21
Booster Batteries.............................................. 21
Battery Care..................................................... 21
Winterizing / Out-of-Service ........................... 21
TROUBLESHOOTING
Electrical.......................................................... 22
Engine...................................................... 23 - 25
WIRING DIAGRAMS
AC Electrical ................................................... 26
DC Electrical ........................................... 27 - 30
Proprietary Information
This publication is the property of Northern Lights, Inc.
It may not be reproduced in whole or in part without the written permission of Northern Lights, Inc.
© Northern Lights, Inc. All rights reserved. Litho U.S.A. Publication number OM773W2 10/09
Table of Contents

OM773LW2 10/09
4
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 sched-
ules must be adhered to more strictly.
Failures begin with minor problems that are over-
looked 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.
Introduction
L, W, W2
M - Northern Lights marine generator set Model number of engine block
Bore Cylinders
77 mm 3
Serial Numbers
MODELS INCLUDED
This manual covers the operating instructions for:
M753W & W2 marine generator sets
Model Numbers
Model numbers give the unit’s application, block model, aspiration, and RPM
Model numbers give the unit's application, block model, aspiration, and RPM:
L - Long stroke
W - New Winding in
Generator End,
2 - Tier II
++
Unit Identification
Northern Lights marine diesel generator set
with a 773 engine, PX-309K2 generator end, and
an AVR.
Northern Lights marine generator set with a
773 engine, PX-309K2 generator end, AVR,
Tier II compliant.
M773LW
M 773
=M773LW2 =
Your set has three serial numbers: 1an engine number stamped
on the block, 2 a generator plate, and 3a 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.
Figure 1: Generator set serial number plate.

OM773LW2 10/09
5
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.
• Use caution in handling fuel. Never refuel a hot
or running engine. Do not smoke while filling
fuel tank or servicing fuel system. Clean up
spilled fuel or oil to prevent potential fires.
• 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 knowledge-
able, 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.
• Never leave engine without proper security.
• Turn the coolant tank cap slowly to relieve pres-
sure 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.
Safety Rules
Warranty

OM773LW2 10/09
6
1. Generator Control Box
2. Air Filter
3. Fuel Filter
4. Fuel Lift Pump
5. Crankcase Vent
6. Lube Oil Fill, Top
7. Coolant Fill
Marine Generator Component Locations
Figure 1 & 2: M773LW with PX-309K2 generator
8. Fuel Injector
9. Stop Solenoid
10. Injection Pump
11. Lube Oil Fill, Side
12. Seawater Pump
13. Lube Oil Drain
14. Base frame
26. Starter
27. Alternator
28. HeatExchangerEnd
Cap
29. Coolant Recovery
Tank
15. Block Drain
16. Fuel Inlet and Return
17. Oil Dipstick
18. Lube Oil Filter
19. Control Panel Plug
20. Generator Data Plate
21. ACCircuitBreakerfor
AVR
22. DC Circuit Breaker
23. Expansion Tank
24. Wet Exhaust Elbow
25. Vibration Mount

OM773LW2 10/09
7
Figure 3 & 4: M773LW2 with PX-309K2
generator end.
Marine Generator Component Locations
1. Generator Control Box
2. DC Circuit Breaker
3. Coolant Recovery
Tank
4. Air Filter
5. Fuel Filter
6. Fuel Lift Pump
7. Fuel Injector
8. Coolant Fill
9. Lube Oil Fill, Top
10. Stop Solenoid
11. Injection Pump
12. Lube Oil Fill, Side
13. Seawater Pump
14. Fuel Inlet and Return
15. Oil Dipstick
16. Lube Oil Filter
17. Oil Drain
18. Generator Data Plate
19. Expansion Tank
20. Heat Exchanger End
Cap
21. Wet Exhaust Elbow
22. Vibration Mount
23. Starter
24. Alternator

OM773LW2 10/09
8
Figure 6-a: Series 3 Generator Control Panel
Control Panels
Figure 5: Series 1-B Generator Control Panel
Figure 6-b: Series 4 Generator Control Panel
1. SHUTDOWN BYPASS-PREHEAT SWITCH
There are two functions built into this switch:
1. Preheats the fuel before beginning the starting
process. Press switch 10-20 seconds before attempt-
ing start-up.
2. Bypasses the safety shutdown feature during
starting process. Keep switch engaged while starting
engine and for 2 to 3 seconds afterwards, allowing oil
pressure to build beyond shutdown set point.
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 8.
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.
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. WATER TEMPERATURE GAUGE
Registers the temperature of the cooling water.
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 engine speed: 1200 or
1800 RPM (60 Hz), or 1500 RPM (50 Hz).
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. A.C. AMMETER
Shows the generator load on each phase. The phase is
selected with the Ammeter Selector switch (Item 9).

OM773LW2 10/09
9
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)
When the switch is placed in the AUTO START posi-
tion, the unit will automatically start when there is a
drop in utility power.
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. D.C. VOLTMETER
When the engine is running, the voltmeter indicates the
voltage output of the alternator.
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. A.C. 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 fre-
quency: 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 7-A: Series 7.0 through Series 7.6 Generator
Control Panels.
Figure 7-B: Status Indicators for Series 7.0 through
Series 7.6 Generator Control Panels.

OM773LW2 10/09
10
BREAK-IN PERIOD
1. The first 100 hours on a new or reconditioned
engine are critical to its life and performance.
2. Constantly 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, then at every 250 hours (consult
Lubricants section for oil recommendation).
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. 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 between
maximum and minimum level 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. Close the sea-cock, check and clean the sea strainer
and reopen the sea-cock.
5. 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 10 seconds
consecutively. If the engine fails to start with the first
attempt, be sure that it has stopped completely for at
least 30 seconds 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 10-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
coolant temperature gauge must be between167°F
and 194°F (75°C to 90°C). 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. Add electrical load.
STOPPING
1. Remove electrical load from the generator set.
2. Move the Engine Control switch to the STOP
position momentarily.
3. Shut off the seacock, fuel valve, and battery switch.
Operating Procedures

OM773LW2 10/09
11
SHUTDOWNS AND ALARMS
1. Generator sets have shutdown systems to stop the
engine in the event of high water temperature or low
oil pressure.
a. Other alarms and shutdowns are available as
optional equipment.
NOTE: Do not rely on your shutdown 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.
If above 205°F (96°C), 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.
c. Make repairs. Restart your generator set after the
temperature gauge registers below 200°F (94°C).
d. Watch the temperature gauge regularly and
turn off the unit if the temperature rises above
205°F (96°C) on Marine units. Repeat trouble-
shooting.
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. Northern Lights, Inc. recommends that you keep the
following spare parts on hand for field service. The
parts are available from your local Northern Lights
dealer.
Marine models have optional “On-Board-Kits,” a
handy box that contains the most common parts you
will need.
2. All owners should have the following:
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
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

OM773LW2 10/09
12
SERVICE 50 250 500 1000 2500
POINT PAGE OPERATION DAILY Hours Hours Hours Hours Hours
ENGINE:
SP1 10 & 14 Check oil level •
SP2 14 Change engine oil 1) 5) ••
SP3 14 Change lube oil filters 1) 5) ••
SP4 15 Check air cleaner, change element @ 1000 hrs. 1) 4) 5) •
SP5 15 Check V-belt tension •
SP6 15 Check valve clearances 1) 2) •
FUEL SYSTEM:
SP7 16 Check primary filter (Racor) 2) 3) •
SP8 16 Change primary filter element (Racor) 2) 3) •
SP9 16 Change secondary fuel filter 1) 3) •
SP10 17 Bleed the fuel system 3)
SP11 19 Check injectors 1) 3) 6) 7) •
SP12 19 Check fuel injection pump 7) •
COOLING SYSTEM:
SP13 10 & 19 Check coolant level •
SP14 20 Check and flush cooling system •
SP15 20 Check and clean heat exchanger •
SP17 20 Change impeller in raw water pump 1) 3) •
SP21 20 Change condition of exhaust elbow 1) 3) •
ELECTRICAL SYSTEM:
SP18 21 Check electrolyte level in batteries •
SP19 21 Check condition of batteries with hydrometer 1) 4) •
OUT OF SERVICE:
SP20 21 Winterizing or out-of-service 3)
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
SP5 Check V-belt tension
SP7 Check primary fuel filter
SP13 Check coolant level
Check sea strainer
SP18 Check electrolyte in batteries
AFTER FIRST 50 HOURS:
SP2/3 Change engine oil and filter
SP6 Adjust valves
AFTER FIRST 100 HOURS:
SP2/3 Change engine oil and filter
EVERY 250 HOURS:
SP2/3 Change engine oil and filter
SP4 Check air cleaner
SP19 Check state of charge of batteries
EVERY 500 HOURS:
SP8 Change primary fuel filter element
SP9 Change secondary fuel filter
SP21 Check condition of exhaust elbow
EVERY 1000 HOURS:
SP4 Replace air cleaner
SP6 Check valve clearances
SP11 Check injectors
SP17 Change impeller
EVERY 2500 HOURS:
SP12 Check fuel injection pump
SP14 Check and flush cooling system
SP15 Check and clean heat exchanger
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, then at 100 hrs., then every 250 hrs.
6) Clean injection nozzles every 1500 hours.
7) For EPA emission standards fuel nozzle needs to be
cleaned every 1500 hours, the fuel nozzle and fuel pump
need to be cleaned, adjusted, or repaired every 3000
hours, and the quality guarantee for these parts is 1500
hours or 2 years.
Servicing Schedule Chart

OM773LW2 10/09
13
Service Record Notes

OM773LW2 10/09
14
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 8: 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 Figure 8. After this, change oil
and filter every 250 hours.
3. During intermittent cold weather operation, change
oil every 100 hours or six weeks, whichever comes
first.
4. Change oil at any seasonal change in temperature
when a new viscosity of oil is required.
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.
10. Engine capacity with new oil filter is:
773LW - 4.2 quarts (4 liters)
773LW2 - 4.75 quarts (4.9 liters)
SP3. CHANGING LUBE OIL FILTER
1. Change the lube oil filter every 250 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 numbers are:
773LW - #140516190
773LW2 - #24-02001
Air Single Multi-
Temperature Viscosity Viscosity
Above 32°F SAE 30W SAE 15-40W
(0°C)
-10 to 32°F SAE 10W SAE 10-30W
(-23 to 0°C)
Below -10°F SAE 5W SAE 5-20W
(-23°C)

OM773LW2 10/09
15
SP4. AIR CLEANER
1. Inspect air cleaner every 250 hours. In dusty condi-
tions, check more often.
2. If dirty, wash element in soapy water. Rinse and dry
thoroughly before re-installing.
Replace if necessary. Part numbers are:
M773LW – #24-22003
M773LW2 – #24-28602
3. 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 daily.
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).
Servicing
Figure 9: Valve Adjustment
SP6. VALVE CLEARANCES
1. Adjust valve clearance after 1000 hours or as
needed.
2. Valve adjustments should be done after the cylinder
head bolts have been re-tightened. Engine should be
cold and NOT running.
3. To bring the No. 1 cylinder to top dead center in the
compression stroke, align the timing mark; the top
mark of the crank pulley with that of the timing gear
case. Remove the rocker arm cover and turn the
crankshaft foward and backward. If the inlet and
exhaust valves of the No. 1 cylinder do not move
it is in top dead center position. When the valves
move, or rock, turn the crankshaft one full turn and
align the top mark of the crank pulley with the top
mark of the timing gear case.
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
9). 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).
Figure 10: Timing Mark

OM773LW2 10/09
16
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.
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 500 hours.
c. If the bowl fills with water, change the primary
and secondary element immediately.
2. Change secondary fuel filter every 500 hours or as
necessary.
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:
773LW
AND 773LW2: #24-52020

OM773LW2 10/09
17
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 11: M773LW 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 11) 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 bleed-
ing 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.

OM773LW2 10/09
18
Figure 12: Remove delivery line flare nuts.
Figure 13: Remove delivery lines.
Figure 14: Remove return line nuts.
Figure 15: Remove return line.
Figure 16: Unscrew injector.
Figure 17: Remove and replace copper sealing washer.
Figure 18: Reinstall injector. Torque to proper tightness.
Servicing

OM773LW2 10/09
19
SP11. INJECTOR SERVICE
1. Injectors should be checked every 1000 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 12).
c. Remove delivery lines by disconnecting from
injectors and injection pump (Figure 13). 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.
d. Remove the return line retaining bolts (Figure 14).
Remove the return line (Figure 15).
e. Unscrew and remove the injectors (Figure 16).
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 17). 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 17).
b. Screw in injector and tighten to 43 or 50 ft/lbs
(6 to 7 kgm) (Figure 18).
NOTE: Overtightening can damage injector.
c. Install return line using new copper sealing above
and below each connection. Tighten return line
retaining bolts to 22 - 30 ft/lbs.
d. Install delivery lines. Leave loose at injectors for
bleeding.
e. Pump hand level on fuel pump to fill lines.
Tighten lines at injectors. 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 2500 hours of opera-
tion. 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 injec-
tion 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: 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 pres-
sure 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.
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

OM773LW2 10/09
20
SP14. COOLING SYSTEM FLUSHING
1. Flush the cooling system every 2500 hours or every
12 months, whichever comes first.
a. Remove expansion tank cap and drain engine
block.
b. Open block drain cock.
Remove plug in lower left
side 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.
2. Coolant Specifications:
Use 50% water / 50% ethylene glycol antifreeze
mix. Antifreeze mixture is recommended as a good
year-round coolant, but not methyl alcohol based
antifreeze because of it’s effect on non-metallic
components and it’s low boiling point. Also, anti-
freeze with high silicate should not be used as it
could case silica gelation problems.
3. Check hoses and connections and repair any leakage.
SP15. HEAT EXCHANGER
1. Clean the heat exchanger core once a year or after
2500 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.
SP17. RAW WATER PUMP
1. Change the seawater pump impeller every 1000 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.
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. When 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.
Servicing