Onan NHC User manual

Oman
Operators
Manual
[Mini©
inhcv
Engine

it is recommended that you read your engine manual and
become thoroughly acquainted with your equipment before
you start the engine.
FuelSysiem
• DO NOT fill fuel tanks while engine is running.
This symbol if used warns of imme¬
diate hazards which will result in
severe personal injury or death.
This symbol refers to a hazard or
unsafe practice which can result in
severe personal injury or death.
DO NOT smoke or use an open flame in the vicinity of the
engine or fuel tank. Internal combustion engine fuels are
highly flammable.
Fuel lines must be of steel piping, adequately secured,
and free from leaks. Piping at the engine should be
approved flexible line. Do not use copper piping for
flexible lines as copper will work harden and become
brittle enough to break.
This symbol refers to a hazard or
unsafe practice which can result in
or product or property damage.
Fuels, electrical equipment, batteries, exhaust gases and
moving parts present potential hazards that can result in
serious, personal injury. Take care in following these recom¬
mended procedures. All local, state and federal codes should
be consulted and complied with.
• Be sure all fuel supplies have a positive shutoff valve.
Exhaust System
• Exhaust products of any internal combustion engine are
toxic and can cause injury, or death if inhaled. All engine
applications, especially those within a confined area,
should be equipped with an exhaust system to discharge
gases to the outside atmosphere.
• Do not use exhaust gases to heat a compartment
ACAUTION
personal injury
AWARNING en 9 me is not designed or in- • Make sure that your exhaust system is free of leaks.
- - tended for use in any type of aircraft . Ensure that exhaust manifolds are secure and are not
Use of this engine in aircraft can result in engine failure warped by bolts unevenly torqued.
and causes serious personal injury or death.
Exhaust Gas is Deadly!
General Exhaust gases contain carbon monoxide, a poisonous gas
• Provide appropriate fire extinguishers and install them in that c an cause unconsciousness and death. It is an odorless
convenient locations. Use an extinguisher rated ABC by anc * colorless gas formed during combustion of hydrocarbon
(sjfpa. fuels. Symptoms of carbon monoxide poisoning are:
• Make sure that all fasteners on the engine are secure and
accurately torqued. Keep guards in position over fans,
driving belts, etc.
• If it is necessary to make adjustments while the engine is
running, use extreme caution when close to hot exhausts,
moving parts, etc.
Protect Against Moving Parts
• Do not wear loose clothing in the vicinity of moving parts,
such as PTO shafts, flywheels, blowers, couplings, fans,
belts, etc.
• Dizziness • Vomiting
• Headache • Muscular Twitching
• Weakness and Sleepiness • Throbbing in Temples
If you experience any of these symptoms, get out into fresh air
immediately, shut down the unit and do not use until it has
been inspected.
The best protection against carbon monoxide inhalation is
proper installation and regular, frequent inspections of the
complete exhaust system. If you notice a change in the sound
or appearance of exhaust system, shut the unit down
immediately and have it inspected and repaired at once by a
competent mechanic.
• Keep your hands away from moving parts.
Batteries
• Before starting work on the engine, disconnect batteries
to prevent inadvertent starting of the engine.
• DO NOT SMOKE while servicing batteries. Lead acid
batteries give off a highly explosive hydrogen gas which
can be ignited by flame, electrical arcing or by smoking.
• Verify battery polarity before connecting battery cables.
Connect negative cable last
Cooling System
• Coolants under pressure have a higher boiling point than
water. DO NOT open a radiator pressure cap when
coolant temperature is above 212°F (100°C) or while
engine is running.
Keep the Unit and Surrounding Area Clean
• Make sure that oily rags are not left on or near the engine.
• Remove all unnecessary grease and oil from the unit.
Accumulated grease and oil can cause overheating and
subsequent engine damage and present a potential fire
hazard.
E-6

Table of Contents
TITLE PAGE
Introduction.
Engine Set-Up.
Operation .
Maintenance.
Periodic Maintenance Schedule
Adjustments. 10
^WARNING
INCORRECT SERVICE OR REPLACEMENT OF PARTS CAN RESULT IN
SEVERE PERSONAL INJURY AND/OR EQUIPMENT DAMAGE. SERVICE
PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL AND/OR
MECHANICAL SERVICE.
1
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Introduction
KNOW YOUR ENGINE
Read this manual carefully, observing all WARNINGS
and CAUTIONS. Operating instructions, adjustments
and periodic maintenance procedures are given so
you ... the owner, can keep your unit running like
new and expect many years of dependable service
from it. Remember ... any machine, regardless of
design or type, will perform only in relation to the service
it receives. Regularly scheduled maintenance lowers
operating costs.
ENGINE MODEL REFERENCE
Identify your model by referring to the MODEL and SPEC
(specification) NO. as shown on the unit nameplate.
Always use this number and the engine serial number
when making reference to your engine.
If a major repair or an overhaul is necessary, Onan
recommends that a competent mechanic either do the
job or supervise and check the work of the mechanic
assigned to do the job to ensure that all dimensions,
clearances and torque values are within the specified
tolerances.
An engine service manual and complete parts catalog
are available at additional cost. Contact your nearest
authorized dealer or Onan Parts and Service Center.
REFERENCE MANUALS
Parts Catalog .. 940-0251
Major Service Manual . 940-0751
These instructions contain the SI metric equivalents following
immediately in parentheses after the U.S. customary units of
measure.
SPECIFICATIONS
Engine Design.Opposed two cylinder,
four cycle, and air cooled
Bore.3.56 inch (90.48 mm)
Stroke.3.0 inch (76 mm)
Displacement.60 CID (983 cm 3 )
Horsepower (3600 RPM)
NHC (Pressure Cooled).25 BHP (18.6 kW)
NHCV (Vacu-Flo Cooled).22.5 BHP (16.8 kW)
Oil Capacity.3.5 qt (3.3 litre)
Oil Capacity with filter change.4.0 qt (3.8 litre)
Compression Ratio .7.0 to 1
TUNE-UP SPECIFICATIONS
Spark Plug Gap.0.025 inch (0.635 mm)
Breaker Point Gap.0.016 inch (0.41 mm)
Valve Lash
Intake .0.005 inch (0.127 mm)
Exhaust.0.013 inch (0.330 mm)
Ignition Timing (static setting).20°BTC
2

Engine Set-Up
Inspect the engine visually. Check for loose or
missing parts and any damage that may have occurred
in shipment.
a r a i iTiniiJI 0il > fuel ’ and coolant have been
AAWlUllun | drained f rom the engine prior to
shipping from Onan.
BATTERIES
The batteries and battery cables used for starting the
engine should be of sufficient size to provide prompt
starting. Undersized batteries will result in poor
starter operation and a very short starter service life.
A WARNINC I l 9 nition of explosive battery gases
AAWAnrvihHj | can cause severe personal injury.
Do not smoke while servicing batteries.
CRANKCASE OIL RECOMMENDATIONS
Fill crankcase with correct amount of oil. Refer to
SPECIFICATIONS for crankcase capacity. Use oils
meeting the American Petroleum Institute (API) clas¬
sification SE or SE/CC.
A WARM I Mr Crankcase pressure can blow out
aawai-uniinij I hot oil and cause serious burns. Do
NOT check oil while the engine is operating.
Oil Level
Check oil level at least every 8 hours of operation.
Check more frequently on a new or reconditioned
engine as oil consumption is higher until the piston
rings seat properly.
When adding oil between oil changes, it is preferable
to use the same brand, as various brands of oil may
not be compatible together. Refer to MAINTENANCE
section for recommended oil change intervals and
procedures.
FUEL RECOMMENDATIONS
a \a/a dmimp I Ignition of fuel can cause serious
j^WAKIMINU | personal injury or d ea t h by fire or
explosion. Do not permit any flame, cigarette, or
other igniter near the fuel system.
Use clean, fresh, unleaded gasoline. Regular leaded
gasoline may also be used but is not a preferred fuel.
Do not use highly leaded premium gasoline. Use of
unleaded gasoline results in less maintenance.
A CAUTION Do not use 9 asolme de-icers. Gaso-
acau IUIN n n e de-icers can cause internal
damage to carburetor and fuel pump parts. Do not
use fuels containing alcohol concentrations greater
than ten percent. Fuel containing alcohol may cause
poor engine performance and internal engine
damage.
Do not overfill crankcase. Excess oil
causes higher operating tempera¬
tures and may cause foaming.
USE THESE SAE VISCOSITY GRADES
If regular leaded gasoline is used continually, carbon
and lead deposits should be removed from the
cylinder heads as required because of engine power
loss. Unleaded gasoline may be used safely after lead
deposits have been removed.
AiAfADkiiM/’' I Spilled fuel can ignite and cause
[ AWARNING J r/ous p ersona/ injury or death .
Never fill the fuel tank when the engine is running.
EXHAUST SYSTEM
Exhaust products of any internal combustion engine
are toxic and can cause injury, or death if inhaled. All
engine applications, especially those within a confined
area, should be equipped with an exhaust system to
discharge gases to the outside atmosphere.
AWARNINC Inhalation of exhaust gases can
AWMniNiiNu j fe su/f In serious personal injury or
death. Use extreme care during installation to ensure
a tight exhaust system.
3

Operation
STARTING
Most engines are equipped with a start-stop switch
and cable controlled choke and throttle.
1. Place the throttle control in the SLOW position
and the choke into the FULL choke position.
2. Turn the ignition switch on and engage starter. If
engine fails to start after 30 seconds determine
the cause. Wait one minute before recranking.
If the engine fails to start at first attempt, rust inhibitor oil used
at the factory may have fouled the plugs. Remove the plugs,
clean in a suitable solvent, dry thoroughly and reinstall. Heavy
exhaust smoke when the engine is initially started is normal
and usually caused by rust inhibitor oil.
3. When the engine starts, gradually push the choke
lever in until the engine runs smoothly.
4. Black smoke from the exhaust and a rough
running engine usually indicate over-choking.
5. To stop the engine, turn the ignition switch to the
OFF position.
AWARNING
Contact with rotating machin¬
ery can cause serious personal
injury or death . Stay clear of rotating components
and ensure that protective shields and guards are
in place and secured before operating machinery .
2. See that nothing obstructs air flow to and from
the engine.
3. Ensure that you are using the proper grade and
weight of oil for ambient temperatures. Check the
oil level each time you fill the fuel tank.
4. Check the battery water more frequently than
every 50 hours which is recommended under
normal conditions. High temperatures cause
faster evaporation.
5. Change crankcase oil and filter more frequently
than recommended under normal conditions.
BREAK-IN PROCEDURE
Controlled break-in is the ideal fitting of all internal
moving metal parts. Using the proper oil and applying
a conscientious maintenance program during this
period helps assure satisfactory service from your
Onan engine.
Maintain the proper cooling and lubrication during
break-in. Run the engine at half load for the first three
hours with intermittent periods of full load to control
engine break-in.
A CAUTION
Using the wrong grade and weight
of oil and high engine operating
temperatures during break-in can cause engine
damage.
Check the oil level at least every five operating hours.
Add oil to keep it at the proper level, but never overfill
as overfilling may cause the oil to foam and enter the
breather system.
COLD WEATHER OPERATION
When the engine is being used in temperatures below
32°F (0°C), check the following items closely:
1. Use the correct grade and weight of oil for the
temperature conditions. Change the oil only when
theengine is warm. If an unexpected temperature
drop occurs when the engine is filled with summer
oil, before starting the engine, move it to a warm
location until the oil will flow freely.
2. Use fresh fuel. Fill the fuel tank after each day’s
use to protect against moisture condensation.
3. Keep the battery in a well-charged condition.
DUST AND DIRT
1. Keep unit clean. Keep cooling system clean.
2. Service air cleaner as frequently as required.
3. Change crankcase oil and filter more often than
recommended under normal conditions.
HOT WEATHER OPERATION
When operating the engine in temperatures above
100°F (38°C), pay particular attention to the fol¬
lowing items to prevent damage:
1. K ee p the engine cooling fins clean and free of
obstruction.
ACAUTION
engine damage.
Plugged or clogged cooling fins
can cause overheating and
OUT-OF-SERVICE PROTECTION
Protect an engine that will be out-of-service for more
than 30 days as follows:
1. Run the engine until it reaches normal operating
temperature.
2. Turn off the fuel supply and run theengine until it
stops.
3. Drain oil from oil base while the engine is still
warm. Refill with fresh crankcase oil and attach a
tag stating viscosity used.
4

4. Remove spark plugs. Pour 1 ounce (2 table¬
spoons or 28 grams) of rust inhibitor or SAE #50
oil into the cylinders. Crank the engine over a few
times. Reinstall spark plugs.
5. Serviceaircleanerasoutlined in MAINTENANCE
section.
6. Clean governor linkage and protect by wrapping
with a clean cloth.
7. Plug exhaust outlet to prevent entrance of
moisture, dirt, bugs, etc.
8. Wipe entire unit. Coat rustable parts with a light
film of grease or oil.
9. Provide a suitable cover for the entire unit.
10. I f battery equipped, disconnect and follow stand¬
ard battery storage procedure.
RETURNING UNIT TO SERVICE
1. Remove cover and all protective wrapping. Re¬
move plug from exhaust outlet.
2. Check tag on oil base and verify that oil viscosity
is still correct for existing ambient temperatures.
3. Clean and check battery. Measure specific gravity
(1.260 at 77° F [25° C]) and verify level to be at
split ring. If specific gravity is low, charge until
correct value is obtained. If the level is low, add
distilled water and charge until specific gravity is
correct.
4. Check that fuel filter and fuel lines are secure,
with no leaks.
5. Check carburetor, adjust if necessary.
6. Connect battery.
7. Start Engine.
After engine has started, excessive blue smoke is exhausted
until the rust inhibitor has burned away.
AWARNING
EXHAUST GAS IS DEADLY!
Exhaust gases from all fuels (including diesel, gasoline, liquid propane, natural
gas) contain carbon monoxide, an odorless and colorless gas. Carbon monoxide
is poisonous and can cause unconsciousness and death. Symptoms of carbon
monoxide poisoning can include:
• Dizziness
• Nausea
• Headache
• Weakness and Sleepiness
e Throbbing in Temples
• Muscular Twitching
• Vomiting
• Inability to Think Coherently
IF YOU OR ANYONE ELSE EXPERIENCE ANY OF THESE SYMPTOMS, GET OUT
INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical
attention. Shut down the unit and do not operate until it has been inspected and
repaired.
Protection against carbon monoxide inhalation includes proper installation,
ventilation and regular, frequent visual and audible inspections of the complete
exhaust system.
5

AWARNING
Accidental starting of the engine
can cause severe personal injury or
death. Disconnect the battery cable when repairs are
made to the engine, controls panel, or associated
equipment.
DAILY CHECKS OR EVERY 8 HOURS
The operator should daily make a complete visual
and audible inspection of the engine. Check the
following before starting the engine for the first time
each day:
1. Check all fuel lines and fittings for possible
leakage.
2. Inspect exhaust system for possible leakage and
cracks. Locate leaks in muffler and piping while
the engine is operating. Repair all leaks imme¬
diately after they are detected for personnel
safety.
3. Inspect air cleaner system for leaks. Make certain
that all clamps and fittings are tight and free of
potential leaks.
4. Check crankcase oil level with the engine off If oil
level is at or below “add” mark on dipstick (Fig¬
ure 1), add sufficient oi I of the proper viscosity as
specified in the ENGINE SET-UP section to bring
oil level to the full mark on the dipstick. Do not
operate engine with oil level below the “add”
mark.
Allow a minimum of 10 minutes for the oil to drain down
before checking. The best time to check the oil is after an
overnight shut-down period.
OIL CHANGE
Change crankcase oil after the first 25 hours of
operation and every 50 hours thereafter. If operating
in extremely dusty, high ambient, or low ambient
conditions change oil more often.
Run engine until thoroughly warm before draining
oil. Stop the engine, place a pan under the drain
outlet and remove the oil drain plug or open the drain
valve. After the oil is completely drained, replace the
drain plug or close the drain valve. Refill with oil of the
correct API classification and appropriate SAE vis¬
cosity grade for the temperature conditions (refer to
ENGINE SET-UP section).
AWARNING
Hot crankcase oil can cause burns if
it is spilled or splashed on skin.
Keep fingers and hands clear when removing the oil
drain plug and wear protective clothing.
Oil level should be to the “full” mark of the dipstick.
Start engine and run for a short time to check for oil
leaks around the drain plug.
OIL FILTER CHANGE
Replace oil filter (Figure 2) after the first 25 hours of
operation, and every 100 hours thereafter. If opera¬
ting in extremely dusty, high ambient, or low ambient
conditions change oil filter more often.
Spin off oil filter element and discard it. Thoroughly
clean filter mounting surface and install new element,
making sure new gasket is inserted in the element.
Apply a thin film of oil to the gasket. Spin element
down by hand until gasket just touches mounting pad
and then turn down an additional 174-1/2 turn. Do not
overtighten.
FIGURE 1. CRANKCASE OIL FILL
FIGURE 2. OIL FILTER
6

With oil in crankcase, start engine and check for leaks
around filter element. Retighten only as much as
necessary to eliminate leaks, but do not overtighten.
IGNITION
Spark Plugs
Check, and regap spark plugs every 100 hours of
operation (Figure 3). Replace spark plugs that show
signs of fouling or electrode erosion.
FIGURE 3. SPARK PLUG GAP
Cleaning Batteries
Keep the batteries clean by wiping them with a damp
cloth whenever dirt appears excessive.
If corrosion is present around the terminal connec¬
tions, remove battery cables and wash the terminals
with an ammonia solution or a solution consisting of
1/4 pound of baking soda added to 1 quart of water.
Be sure the vent plugs are tight to prevent cleaning
solution from entering the cells.
After cleaning, flush the outside of the battery, the
battery compartment, and surrounding areas with
clear water.
Keep the battery terminals clean and tight. After
making connections, coat the terminals with a light
application of petroleum jelly or non-conductive
grease to retard corrosion.
Checking Specific Gravity
Use a battery hydrometer to check the specific
gravity of the electrolyte in each battery cell.
Hold the hydrometer vertical and take the reading.
Correct the reading by adding four gravity points
(0.004) for every five degrees the electrolyte tempera-
ture is above 80° F (27° C) or subtracting four gravity
points for every five degrees below 80°F (27°C). A
fully charged battery will have a corrected specific
gravity of 1.260. Charge the battery if the reading is
below 1.215.
Breaker Points
Check breaker points every 100 hours. Replace
points and condenser every 200 operating hours.
Replace sooner if points are pitted or burned. See
ADJUSTMENTS section.
COOLING SYSTEM
Check and clean cooling fins and chaff screen at least
every 50 hours. Remove any dust, dirt or oil which
may have accumulated.
BATTERIES
Disconnect negative ground strap from the battery
before working on any part of the electrical system or
engine.
Disconnect positive terminals before charging batter¬
ies to avoid damaging alternator or regulator.
AWARNING
Ignition of explosive battery gases
can cause severe personal injury.
Do not smoke while servicing batteries.
Checking Electrolyte Level
Check the level of the electrolyte (acid and water
solution) in the batteries at least every 50 hours of
operation.
Fill the battery cells to the bottom of the filler neck. If
cells are low on water, add distilled water and
recharge. If one cell is low, check case for leaks. Keep
the battery case clean and dry. An accumulation of
moisture will lead to a more rapid discharge and
battery failure.
ACAUTION
Do not add water in freezing weather
unless the engine is to be run long
enough (two or three hours) to assure a thorough
mixing of water and electrolyte.
Storing Batteries
If the engine is to be stored for more than 30 days,
remove the batteries. With the electrolyte level at the
bottom of the split ring, charge the battery before
storing it. After every 30 days the battery is in storage,
bring it back up to full charge. To reduce self¬
discharge, store the battery in as cool a place as
possible so long as the electrolyte does not freeze.
7

CRANKCASE BREATHER
This engine uses a crankcase breather valve for
maintaining crankcase vacuum. If the crankcase
becomes pressurized as evidenced by oil leaks at the
seals, clean baffle pack and valve in a suitable
solvent. Check and clean valve screens and baffle
every 200 hours of operation. See Figure 4.
FIGURE 4. CRANKCASE BREATHER
AIR CLEANER
Cartridge Air Cleaner
Check and clean air cleaner element every 25 hours
(Figure 5). Clean by gently tapping element on a flat
surface. Replace the element every 200 hours. Clean
or replace more frequently in dusty operating
conditions.
Air Cleaner Wrapper (Pre-Cleaner [if used])
Wash in water and detergent and squeeze dry like a
sponge (Figure 5). Allow to dry, then coat evenly with
two tablespoons (28 grams) of SAE 30 engine oil.
Knead into and wring excess oil from pre-cleaner.
Reinstall over cartridge.
Failure to adequately wring out excess oil from the wrapper may
cause drop in engine horsepower due to an increased restriction of
inlet air.
WING NUT
COVER
OPTIONAL
^ POLYURETHANE
PRE-CLEANER
BREATHER TUBE
1. WASH
2. SQUEEZE DRY
3. COAT WITH OIL
4. INSTALL OVER PAPER ELEMENT
EXHAUST SYSTEM
Make regular visible and audible inspections of the
exhaust system throughout the entire life of the
engine. Locate leaks in muffler and piping while the
engine is operating. Repair all leaks immediately after
they are detected for personnel safety.
AWARNING
Inhalation of exhaust gases can
result in serious personal Injury or
death. Inspect exhaust system audibly and visually
for leaks daily. Repair any leaks immediately.
FIGURE 5. AIR CLEANER ASSEMBLY
8