Onan MCCK Instruction Manual

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MANUAL
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CATALOG
ONAN
2515 UNIVERSITY AVE. S.E.
MINNEAPOLIS, MINN. 55414
A DIVISION OFSTUDEBAKER CORPORATION
IN CANADA: ONAN GENERATORS CANADA LTD., P.O. BOX 652, GUELPH, ONTARIO

TABLE OF CONTENTS
TITLE PAGE
Installation 7
Operation
Adjustments 17
Maintenance 20
Trouble Shooting 22
Parts Catalog 25
ONAN
ELECTRIC GENERATING PLANTS
MCCK
927-350 SERIES 5AC68
PERFORMANCE
CERTIFIED
We certify that when properly installed and operated
this Onan electric plant will deliver the full power and the
voltage and frequency regulation promised by its nameplate
and published specifications. This plant has undergone several
hours of running-in and testing under realistic load conditions,
in accordance with procedures certified by an independent
testing laboratory.
2010 UNIVERSITY AV«. S.E. ■ MINNEAPOLIS, MINN. BB4U
A £>l 1/tStOH OF SrUDH^KM CORPORATE
IMPORTANT...RETURN WARRANTY CARD ATTACHED TO UNIT
*
i
£

GENERAL INFORMATION
THIS OPERATOR’S MANUAL PROVIDES INFORMATION FOR PROPER
INSTALLATION, OPERATION, AND MAINTENANCE PROCEDURES OF
YOUR ONAN UNIT. AN APPLICABLE WIRING DIAGRAM WAS ALSO IN¬
CLUDED AT TIME OF SHIPMENT. RETAIN FOR FUTURE REFERENCE!
WE SUGGEST THIS MATERIAL BE KEPT HANDY SO THAT IT CAN BE
READILY REFERRED TO WHEN NECESSARY, EITHER FOR ORDERING
PARTS OR MAKING EQUIPMENT ADJUSTMENTS.
FOR MAJOR REPAIR INFORMATION A SERVICE MANUAL IS AVAIL¬
ABLE. IF A MAJOR SERVICE MANUAL, ADDITIONAL OPERATORS
MANUAL, AND/OR WIRING DIAGRAM IS REQUIRED, CONTACT YOUR
NEAREST ONAN DISTRIBUTOR. THERE WILL BE A CHARGE FOR
THIS MATERIAL.
BE SURE TO INCLUDE COMPLETE ONAN MODEL, SPEC., AND SERIAL
NUMBER AS SHOWN ON ONAN NAMEPLATE ATTACHED TO UNIT. THIS
IS ESSENTIAL IN FURNISHING YOU WITH THE PROPER INFORMATION.
2

INTRODUCTION
When instructions in this manual refer to a specific
model of generating plant, identify the model by
referring to the MODEL AND SPECIFICATION NO.
as shown on the plant nameplate. Electrical character¬
istics are shown on the lower portion of the plant
nameplate.
How to interpret MODEL and SPEC. NO.
605MCCK-3R /
--
1 2
B
3 4
1. Factory code for general identification.
2. Specific Type:
M - MANUAL. Manually cranked. For permanent or
portable installations.
E - ELECTRIC. Electric starting at the plant
only.
R - REMOTE. Electric starting. For permanent
installation, can be connected to optional acces¬
sory equipment for remote or automatic control of
starting and stopping.
3. Factory code for optional equipment.
4. Specification (Spec.)letter (advances when factory
makes production modifications).
TYPICAL MODEL MCCK
MANUFACTURER'S WARRANTY
The Manufacturer warrants, to the original user, that each
product of its manufacture is free from defects in material
and factory workmanship if properly installed, serviced and
operated under normal conditions according to the Manu¬
facturer's instructions.
Manufacturer's obligation under this warranty is limited to
correcting without charge at its factory any part or parts
thereof which shall be returned to its factory or one of its
Authorized Service Stations, transportation charges prepeiu,
within one year after being put into service by the original
user, and which upon examination shall disclose to U le
Manufacturer’s satisfaction t o have been originally defective.
Correction of such defects by repair to, or supplying of
replacements for defective parts, shall constitute fulfillment
of all obligations to original user.
This warranty shall not apply to any of the Manufacturer's
products which must be replaced because of normal wear
which have been subject to misuse, negligence or aeciden
or which shall have been repaired or altered outside of the
Manufacturer's factory unless authorized by the Manufacturer,
Manufacturer shall not be liable for loss, damage or expense
directly or indirectly from the use of its product or from any
cause.
The above warranty supersedes and is in lieu of all other
warraotiea, expressed or implied, and of all other liabilities
or obligations on part of Manufacturer. No person, agent or
dealer is authorized to give any warranties on behalf of the
Manufacturer nor to assume for the Manufacturer any other
liability in connection with any of ita products unless made
in writing and signed by an officer of the Manufacturer.
DATED AUGUST I, 1943
t
3

SPECIFICATIONS
Nominal dimension of plant (inches)
Height
Width
Length
Number cylinders
Displacement (cubic inch)
Cylinder bore (inches)
Piston stroke (inches)
Oil capacity
RPM (for 60-cycle)
RPM (for 50-cycle)
Compression ratio
B.H.P (1800 rpm)
Battery voltage
Battery size
SAE group 1H
Amp/hr. SAE rating, 20-hr. (nominal)
Battery charge rate, amperes
Ventilation required (cfm 1800 rpm)
Generator
Combustion
Output rated at unity power factor load
Rating (output in watts)
50-cycle AC, intermittent service
50-cycle AC, continuous service
60-cycle AC, intermittent service
60-cycle AC, continuous service
AC voltage regulation in i %
AC frequency regulation in %
Revolving armature-type generator
120/240- volt single phase model.reconnectible
Rotating - type exciter
Model Series
4MCCK 605MCCK
24
24
22
22
30
33
2
2
49.8
49.8
3-1/4
3-1/4
3
3
4 qts
4 qts
1800
1800
1500 1500
7: 1
7: 1
13.0
13.0
12 V
12 V
two, in
two, in
series
series
105
105
2-3 low
2-3 low
5-8 high
5-8 high
75
75
32
32
1-phase
1-phase
3500
5500
3500
5000
4000
6500
4000
6500
3
3
5
5
Yes
Yes
Yes
Yes
Yes
Yes
4

OPTIONAL EQUIPMENT
1. REMOTE START-STOP SWITCH
SPDT, momentary contact, center-off type.
2. SWITCH80ARD w , _ . .
Instruments to read ac amperes, and ac volts, and to break overloaded ac circuit.
Desirable information for operator. For wall mounting.
3. INSTRUMENT PANEL .
Part of plant control box assembly. Instruments to read ac amperes and ac volts,
and to break overloaded ac circuit. Desirable information for operator. Plants with
instrument panel have no room for optional ac receptacles.
4. AC RECEPTACLES
Convenience for plugging in ac loads. Plants with ac receptacles have no room for
optional instrument panel.
5. AUTOMATIC DEMAND CONTROL
Starts and stops plant automatically.
6. CONTROL-O-MATIC j ..
A ^-function automatic control which automatically starts and stops plant, supplies
current on demand and automatically runs bilge blower.
7. LOAD TRANSFER CONTROL
Controls running of plant and transfers load.
8 . HEAT EXCHANGER COOLING
Closed system using fresh water in plant.
9. LOAD TRANSFER SWITCH
Three-pole, three-position to select generator or shore power.
10 .
AQUA LIFT MUFFLER t ,
High-efficiency silencer for plants which discharge cooling water into exhaust.
able for above or below water-line installation.
Suit-
11. SEPARATE FUEL TANK
Various sizes.
12. EXHAUST LINE TEMPERATURE SWITCH
Shuts down plant if water flow fails.
13. OTHER
See your dealer.
r
5

SUPPORTS.
I MU FI
WATER LINE FROM
MANIFOLD WATER
OUTLET
HIGH WATER \
TEMP. CUT- \ Q
OFF SWITCH
-RUBBER
HOSE
_ ENGINE
GENERATOR
RUBBER
HOSE.
.PITCH
I '
■ ' - pooT RUBBER
r pE * HOSE
VENTILATED
BATTERY BOX
SEA COCK^SC"
RAW WATER LINE
-FILTER
WARNING: Do not u*e scoop type water inlet fitting*
on electric plant* using Aqualift muffler
system*.
WATER LINE
Recommended flush type
ttwu-hull fitting and water
filter.
TO
ELECTRIC
PLANT
AQUALIFT
SIPHON
BREAK
HANGER STRAPS
-VACUUM RELIEF
VALVE
"ADAPTER
''''ELBOW (2)
— RUBBER HOSE
■ •—WATER OUTLET
■ E XHAUST WATER
INJECTION ELBOW
EXHAUST OUTLET
TYPICAL
BELOW WATER LINE
INSTALLATION
L V WATER
FILTER
3^ STRAINER
V FLUSH THRU-
HULL FITTING
CAUT/OA/ /
,CLAMP ^
EXHAUST \ £ XHA{J * T
vnz? AND
HOS . E , COOLING
\ J ' WATER
^ / OUT
CLAMP -
WARNING: Install Siphon Break Kit M155K950 if exhaust
injection elbow is below load water line. Locate the Siphon
j Break at least 12” above load water line and in a vertical
i position. Remote mounting the siphon break is permissible
within a 5' radius oi water injection exhaust elbow. Vertical
position and height oi valve must be maintained.
"I" ^
BRACKET-
'BOLT
ABOVE WATER LINE
INSTALLATION
Figure I. Typical Installation
6

INSTALLATION
GENERAL
Proper installation is very important. Give attention to
the following points: Adequate generator cooling air,
discharge of circulated air, adequate fresh air, adequate
engine cooling water, discharge of circulated water, dis¬
charge of exhaust gases, electrical connections, fuel
connection, sturdy and flat floor and accessibility for
operation and service. Use this manual as a guide to
help with the installation. Refer to Typical Installation,
Figures 1 and2. For more complete instructions, request
Onan Technical Bulletin T-021.
Installations must be considered individually, and ex¬
ecuted in compliance with all regulations which may
affect the installation. The advice and guidance con¬
tained in the booklet, Fire Protection Standard for Motor
Craft: (NFPA No.302) offered by the National Fire Pro¬
tection Association International, Boston 10, Mass¬
achusetts, will be helpful to the installer of equipment
in vessels.
Figure 2. Mounting Dimensions
LOCATION
Select a dry, properly-ventilated location for the plant,
preferably near the main keel, above low-lying vapors
and free from splash from the bilge. Provide accessibility
for minor servicing operations. draining of the crankcase
lubricating oil and the cooling system.
A 2-1/2” clearance around the unit is required to permit
it to rock on its mounts without restraint. Use flexible
exhaust line, fuel line, battery cables, and electrical
wires.
To install cone-type mounting cushions (Fig.3). position
the plant on the drip pan and place the cushions under
the oil base and generator support. Always use cushions
with highest part number (part number is shown on the
cushion) on the generator end. Secure the plant, to the
drip pan with the associated hardware (Fig.3). Add thin
flat washers to maintain approximately 1/16” clearance
between snubber washer and flat washer. Cushion de¬
flection under load should be approximately 3/16”.
CAPSCREW
LOCK WASHER
FLAT WASHER
SNUBBER
GENERATOR OR
OIL BASE MOUNT¬
ING FOOT
CUSHION
MOUNTING SPACER
BUSHING
DRIP PAN
Figure 3. Cone-Type Mounting Cushion
Install two hold-down clamps to the drip pan (front and
rear or both sides). Secure the clamps to the mounting
base.
FUEL TANK AND LINES
If a separate fuel tank is used, install it so the bottom
of the tank will be less than 4 feet below the fuel pump.
To prevent siphoning if a system leak occurs, position
the tank below the level of the engine pump,or use a
siphon break system.
If a fuel tank is shared, do not connect to an existing
line at a point above the fuel supply level. This avoids
starving the plant (See Fig.4 and 5).
MOUNTING
The floor should be flat, and give support directly under
the plant mounting points.
If vertical fuel lift exceeds 4 feet, or vapor lock occurs,
install an auxiliary electric fuel pump near the fuel sup¬
ply-

Figure 4. Fuel System
Figure 5. Fuel System
Use an approved flexible rubber fuel line next to the
engine. Install the fuel supply line from near the bottom
of the supply tank to the 1/8" pipe-tapped inlet of the
fuel pump (see Fig.6).
A shut-off valve at the tank and near the plant is recom¬
mended for service convenience (Fig.6).
OIL DRAIN
The oil drain may be extended to suit the installation.
The oil base has a 1/2” pipe-tapped hole.
Figure 6. Fuel Shut-Off Valve
VENTILATION
Generating plants require fresh air for combustion and
generator cooling. Onan recommends that the ventilation
system he able to deliver 1-1/2 to 2 times the air re¬
quired by the plant. When the ventilation system depends
on wind or boat motion, use powered exhausters to pro¬
vide ventilation when the boat is not in motion. For more
information, refer to Onan Technical Bulletin T-021.
EXHAUST
See Installation, Fig.l and 2. The engine exhaust con¬
nection is 1”, pipe-tapped. Pipe exhaust gases outside
of the hull - exhaust gases are deadly poisonous ’
Install a separate exhaust line as follows:
1. Above vessel load water line.
2. Pitched downward to prevent water backflow.
3. Shield line near combustible material.
4. Use flexible hose or tubing (see Fig.l and 2).
5. For turns, use sweeping (long radius) elbows.
6. Increase one pipe size for every 10' increase in pipe
length.
Provide a tee for water line connection for wet exhaust
(Fig.7). Refer to Water Discharge Line. Raise the dry
portion of the exhaust line high enough to prevent water
back-flowing into the engine. Onan recommends using
the Aqua Lift muffler for maximum silencing efficiency
and ease of installation.
8
Figure 7. Water Outlet Connections

The recommended Neoprene muffler (silencer) is an
Elasto-Muffle brand, size mark O.and two bushings,size
AB (fits 1-5/8” O.D.). A cast iron or stainless-steel
muffler is also available. Provide a recommended (or
equal) silencer and install it near the end of the wet
exhaust line.
Caution: Dry exhaust will damage the neoprene silencer.
WATER SUPPLY LIME
A continuous supply of cooling water is required. The
water pump inlet is a hose fitting for 1/2” I.D. hose
(see Fig.8). Use a section of non-collapsible hose near
the plant (or for the entire run) to absorb vibrations. The
inside diameter of the plumbing must be at least 1/2”.
Use Permatex or other pipe sealer on all pipe fittings
in supply line to pump. Normally, the pump should de¬
liver 3.5 gallons of cooling water per minute. Measure
the discharged water flow after thermostat opens, to
be sure the supply line is large enough. Reduce resis¬
tance on pipe runs longer than 5’ by using larger in¬
side diameter plumbing. To prove suction line is air¬
tight, see that no bubbles appear in discharged water.
An air teak reduces lubrication and shortens pump im¬
peller life. Install a strainer in the water suction line
inlet where it is accessible for cleaning.
Figure B. Water Pump Inlet Ho*e
WATER DISCHARGE LIME
The 1/2” I.D. water outlet hose fitting is on the ex¬
haust manifold next to the exhaust outlet (see Fig.7).
Use plumbing at least as large as the supply line. Use
a section of hose near the plant or the entire run. Con¬
nect the line to discharge the heated water into the ex¬
haust line several feet ahead of the Aqualift or neo¬
prene silencer. Make sure water cannot back flow into
the exhaust line. See Optional Heat Exchanger Cooling.
HEAT EXCHANGER COOLING (Optional)
Closed-type cooling systems are commonly referred to
as fresh water cooling or heat exchanger cooling. Water
circulated through the engine is called fresh water, hot
water , efc. Water circulated through the heat exchanger
only is called raw water, sea water, cold water, dis¬
charged water, etc. This system with an antifreeze cool¬
ant is recommended where freezing conditions exist, or
where the owner wants to prevent the possibility of
salt water problems.
Caution: Do not use the existing neoprene impeller
water pump in the hot water side of the cooling system
Heat or soluble oil (in many rust inhibitors and anti¬
freeze s) wifi damage the impeller. Instead, connect the
neoprene impeller pump on the cold water side. Use a
metal impelter, centrifugal-type water pump (Oberdorfer
1-GP, or equal) in the fresh water side. Drive it with a
belt from the plant power take-off (see Fig-9). _
FRESH WATER FROM
MANIFOLD
HEAT
EXCHANGER RAW WATER TO
EXHAUST
MANIFOLD
CYLINDER HEAD
DETAIL B
DRAIN
J
hTOHEAT EXCHANGER
PUMP
‘TO ENGINE PUMP
-EXHAUST OUTLET
GOVERNOR ADJUSTMENT
ENGINE PUMP
OIL PRESSURE
GAGE
LOW OIL PRESSURE
CUT-OFF SWITCH
BELT
HEAT EXCHANGER
PUMP
HIGH WATER
TEMPERATURE
SWITCH
DRAIN
HEAT
EXCHANGER
.t PUMP
RAW WATER
ENGINE PUMP
TO HEAT EXCHANGER
(INSIDE FITTING)
TO HEAT EXCHANGER
(REAR FITTING)
Figure 9. Cooling System Details
9

BATTERY CONNECTION
Exciter Cranked Plant: Refer to the wiring diagram and
Fig. 11.Plants are designed for negative (-) ground only.
The discharged water leaves at the heat exchanger (Fig.
10). Supply line connections in both systems are the
same . For general comments that apply in all cases,
refer to the instructions for standard cooling systems
in this section.
Fill the closed cooling system with clean, alkali-free
water to the proper level in the expansion tank. Add
an approved rust inhibitor to the coolant. If the plant
will be operated in freezing temperatures, use the nec¬
essary proportion of anti-freeze, and test it periodically.
Cooling system capacity (including heat exchanger) is
7 pints.
FRESH WATER
'FROM MANIFOLD
LAT WASHER
HEAT-
EXCHANGER
UPPER
BRACKET
STRAP
LOWER
BRACKET
SALT WATER
IT
STRAP
TO HEAT
EXCHANGER
PUMP
Figure tO. Heat Exchanger
Follow Onan battery recommendations. Use two 6-volt
batteries connected in series for a 12-volt power source.
See Fig. 11. Connect battery positive (+) terminal to the
start solenoid located in the control box. Connect the
negative (-) terminal to a good ground on the generator
frame. Enter rear of control box to install battery cable.
Caution: Do not disconnect starting batteries while
plant is running. The resulting over-voltage condition
will damage electric choke and control components.
REMOTE START-STOP SWITCH (Optional)
For remote control of starting and stopping, use three
wires to connect a remote switch (SPDT,momentary con¬
tact, center-off type) to the terminal block marked B+,
1,2,3 in the plant control box (Fig. 12). Use correct wire
size according to switch distance from plant.
LOAD WIRE CONNECTIONS
The plant nameplate shows the electrical output rating
of the plant in watts .volts, and cycles. The plant wiring
diagram shows the electrical circuits and connections
necessary for the available output voltage. Also see
Figures 13 and 14.
Meet all applicable electrical code requirements. Work
should be done by a qualified serviceman or electrician
because the installation may be inspected for official
approval. Plant control boxes have knockout sections
to accommodate load wires. Use flexible conduit and
stranded load wires near the plant to absorb vibration.
Use sufficiently large insulated wires. Strip insulation
from wire ends as necessary for clean connections. Con¬
nect each load wire to the proper generator output lead
inside the plant box. Insulate bare ends of ungrounded
wires. Use a bot (through the control box) to connect
the grounded (i) generator lead and load wire. Install
a fused main switch (or circuit breaker) between the
generating plant and load.
Figure II. Battery Connections
10

Output Lead Markings: Revolving armature generator Instructions for connecting an automatic load transfer
leads are marked Ml,M2, etc. These identifying marks switch are included with such equipment. See fig.11.
also appear on the wiring diagram.
Automatic Control: Use with negative ground electrical
Shore Power: If the installation connects to shore power, system only. If the electrical system is positive ground
install a double-throw transfer switch (either manual or and cannot be converted,use a separate battery conn-
automatic type), such as Onan #30SB204, to prevent ected to negative ground for plant and control operation,
feeding generator output into the shore power source Use a suitable grounding system for the entire vessel to
lines and to prevent commercial power and generator prevent electrolytic action which may be caused by im-
output from being connected to the load at the same time. proper connections of mixed-polarity grounding systems.
Figure 12. Remote Control Wiring
Figure 13. Load Wire Connections
11

TO LOAD
GENERATOR
GROUNDED CURRENT CARRYING CONDUCTOR
120-V. UNGROUNDED CURRENT CARRYING CONDUCTOR
V.
FUSE OR CIRCUIT
BREAKER
THESE LINES FROM
DOCKSIDE POWER SOURCE
Figure 14. Shore Power Wiring Connections
12

OPERATION
INITIAL START
Check the engine to make sure it has been filled with
oil and fuel. Fill cooling system and prime water pump
(Fig.8). If engine fails to start at first attempt, inhibitor
oil used at the factory may have fouled the spark plugs -
remove, clean in gasoline, dry thoroughly and install
Heavy exhaust smoke when the engineis first started is
normal, and is caused by the inhibitor oil.
NOTE: The Control-O-Matic will run the bilge blower
for about 5 minutes before cranking the engine. The
blower cycle may be eliminated; see Conhrol-O-Matic
section.
Crankcase Oil: Use a good-quality detergent oil that
meets the API (American Petroleum Institute) service
designations MS.MS/DG, or MS/DG. Recommended SAE
oil numbers for expected ambient temperatures are as
follows:
OIL CAPACITY - 4 QTS.
Above 90° F SAE 50
30°F to 90° F SAE 30
0°F to 30° F SAE 10W
Do not use service DS oil. Do not mix brands or grades.
Refer to Maintenance Section for recommended oil chan¬
ges and complete lubricating oil recommendations.
Rec«HKended Fuel: Use clean, fresh, regular grade
automotive gasoline. Do not use highly leaded premium
types. Never fill the tank when the engine is running.
Leave some fuel expansion space. Open fuel line valve
(when used).
The following shows the sequence of operation. This
shows operation with manual control at the plant and
automatic control .either at the plant or remotely located.
STARTING SEQUENCE
1. Operator pushes START button or plant is started by
remote control.
2. Start solenoid energizes.
3. Battery current flows to
a) series field
b) STOP relay
c) eleetric choke
4. Ignition coil fires spark plugs when breaker points
open.
5. Engine starts
6. Operator releases START button
7. Start disconnect relay energizes
8. Engine continues running.
STOPPING SEQUENCE
1. Operator pushes STOP button
2. Stop relay opens ignition circuit
3. Engine stops
4. Operator releases STOP button.
EMERGENCY SHUTDOWN
An emergency stop is caused by low oil pressure or high
water temperature.
1. Low oil pressure switch closes.emergency relay ener¬
gizes, opening ignition circuit.
2. High water temperature switch opens ignition circuit.
3. Engine stops.
NOTE: If shutdown is caused by high water temperature,
plant will crank for about 90 seconds. If it does not
start, it will stop cranking.
APPLYING LOAD
Allow plant to warm up before connecting a heavy load
and keep the load within nameplate rating. Continuous
generator overloading may cause high operating tempera¬
tures that can damage the windings
BATTERY CHARGING
The battery charge rate is controlled by a charge reg¬
ulator. This regulator is pre-set to allow the proper charge
rate at operating speed. Do not attempt to change this
setting.
This regulator is pre-set to allow the proper charge rate
at operating speed.Do not attempt to change this setting.
SAFETY DEVICES
A high-water-temperature switch in the cooling system
stops the plant if the engine overheats.
The engine has a lew-oil-pressure switch which will
stop the plant through an emergency relay in the control
if oil pressure drops below a safe operating pressure.
After an emergency stop, investigate and correct the cause.
13

The RESET button must be pressed before re-starting.
A one minute time limit is necessary before the RESET
button can be pressed after an emergency stop. If the
plant is under automatic control, a re-start will be at¬
tempted automatically.
PLANT EXERCISE
Infrequent use results in hard starting. Operate plant
one 30-minute period each week. Run longer if battery
needs charging, or keep battery charged with a separate
charger.
EMERGENCY OPERATION IF BATTERY FAILS
The remote-type revolving-armature plant needs a battery
for electric choke, ignition and limiting exciter voltage.
If the battery fails completely and the plant must be oper¬
ated during an emergency, a battery can be shared with
other equipment having an alternator. Do not disconnect
the plant charging circuit, as damage will occur to the
ignition relay from the increased voltage. Instead, con¬
sider disconnecting other equipment and using that bat¬
tery.
BREAK-IN PROCEDURE
No matter how carefully engine parts are manufactured
or expertly assembled, there are always microscopic
variations in fit between metal parts such as pistons,
rings, main and connecting rod bearings.
Break-in or ideal fitting of all internal moving metal
parts can best be achieved by maintaining proper cooling
and correct lubrication during the running-
BREAK-IN PROCEDURE
No matter how carefully engine parts are manufactured
or expertly assembled, there are always microscopic
variations in fit between metal parts such as pistons,
rings, main and connecting rod bearings.
Rrea*-/n,or ideal fitting of all internal moving metal
parts can best be achieved by maintaining proper cooling
and correct lubrication during the running-in period.
Break-in can take as little as ten operating hours or it
may take many hundreds of hours. Extended periods of
very heavy engine loading (above rated horsepower or
electrical output)during this initial service period can
cause severe cylinder scoring or bearing galling. On the
other hand, extended periods of very light loading during
initial break-in may cause cylinder wall glazing and/or
poor piston ring seating. Engine parts damage can also
be caused by using the wrong type or viscosity of oil,
and allowing the engine to run at too high a temperature
during break-in.
All engines use more oil than normal during the first
hours of operation. As internal moving parts are run-in by
controlled operation, oil consumption should gradually
decrease until the rate of consumption is stabilized. It
is extremely rare that oil consumption drops to zero. AH
engines use some oil, even when in perfect condition and
properly broken-in. Oil consumption varies according to
engine design, engine (piston) speed, size of engine,
type of oil, oil viscosity, length of operating periods,
operating temperatures, engine loading, etc. As engine
operation is continued, clearances between moving parts
increase slightly due to normal wear of piston rings,
cylinder walls, valve guides, oil seals, etc.These clear¬
ances increase until oil consumption is excessive, and
engine parts have to be replaced and/or refitted. This
usually takes thousands of hours.
Each Onan engine is run-in at the Onan factory for a
minimum of three hours. This is not enough running time
to completely break-in the engine. Proper completion ot
the break-in period is the customer’s responsibility.
Generator sets manufactured by Onan can be loaded to
full nameplate rated output (not until they bog down) as
soon as they are put into operation. It is recommended
during this first few hours of operation that generator
sets be loaded to 80% of rated capacity. Initial heavy
loading helps seat piston rings and brings oil consump¬
tion to normal in the shortest time.
During break-in, check oil level at least every eight (8)
operating hours. Add oil if the level is at low on the
dipstick. Never over-fill. This may cause oil to foam and
enter the breather system.
Drain the initial oil fill after 50 hours of operation while
the engine is hot.
Controlled break-in with consistent use of proper oil
from a reputable supplier and a conscientiously-applied
maintenance program will help assure satisfactory serv¬
ice for thousands of hours from your Onan electric plant.
OUT-OF-SERVICE PROTECTION
Protect a plant that is to be out of service for more than
30 days as follows:
1. Run plant until thoroughly warm.
2. Turn off fuel supply and run until plant stops.
3. Drain oil from oil base while still warm. Refill and
attach a warning tag, stating oil viscosity used.
4. Remove each spark plug. Pour 1 oz. (two tablespoons)
of rust inhibitor (or SAE #50 oil) into each cylinder.
Crank engine slowly (by hand) several times. Install
spark plugs.
5. Service flame arrester.
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 generator brushes, slip rings, etc. DO NOT AP¬
PLY LUBRICANT OR PRESERVATIVE TO BRUSHES
AND RINGS.
9. wipe entire unit. Coat parts that can rust with a bright
film of grease or oil.
10. Provide a suitable cover for the entire unit.
11. Drain cooling system if danger of freezing exists
during storage.
12. If battery is used, disconnect and follow standard bat¬
tery storage procedure. Do not allow batteries to be¬
come fully discharged.
14

HIGH TEMPERATURES
1. See that nothing obstructs air flow to and from the
plant.
2. Keep cooling Bystem clean. Maintain water level in
closed system cooling.
3. Keep ignition timing properly adjusted.
LOW TEMPERATURES
1. Use correct SAE oil for temperature conditions. Change
oil only when engine is warm. If an unexpected tem¬
perature drop causes an emergency, move the plant
to a warm location until oil flows freely.
2. Use fresh regular grade (not premium) gasoline. Protect
against moisture condensation. Below 0°F, adjust
main jet fa slightly richer fuel mixture.
3. Keep ignition system clean, properly adjusted, and
the batteries in a well-charged condition.
4. Partially restrict cool air flow, but use care to avoid
overheating.
5. Add good quality anti-freeze if danger of freezing
exists.
DUST AND DIRT
1. Keep plant clean. Keep cooling system clean.
2. Service flame arrester as frequently as necessary.
3. Change crankcase oil every 50 operating hours.
4. Keep oil and gasoline in dust-tight containers.
5. Keep governor linkage clean.
6. Clean generator brushes, clip rings, and commutator;
do not remove normal (dark brown) film. Do not polish.
HIGH ALTITUDE
For operation at altitudes of 2500 feet above sea level,
close carburetor main jet adjustment slightly to maintain
proper air-to-fuel ratio (refer to the Adjustments Section).
CONTROL -0-MATIC
Description
The Control-O-Matic is an automatic control which
performs three functions. It is an engine-control, an
automatic-demand control, and a bilge-blower control,
all contained in one top-mounted control box. The
front panel of this box holds a charge ammeter, an
emergency relay and a 3-position toggle switch.
With the switch in the AUTO position, the Control-O-
Matic will monitor the AC load circuit and:
1. sense a load on the AC line.
2. close the bilge blower circuit (when used), for ap¬
proximately 5 minutes, depending on ambient tem¬
perature.
3. open the bilge blower circuit.
4. start the electric plant.
5. sense when all the load is removed .
6. s top the electric plant.
Operation
When the switch is in the RUN position, the bilge
blower control goes through its control cycle before
the electric plant cranks and starts. With the switch
in AUTO position, the engine will crank and supply
current on load demand after the bilge blower con¬
trol cycles. When the load on the AC line is removed,
the plant will stop. The plant stops when the switch
is moved to the STOP position.
CONTROL-O-MATIC Operation (Optional)
A 3-position toggle switch controls plant operation.
The operator may choose either of two running proce¬
dures.
1. Move switch to RUN position. The bilge blower
control will go through its cycle, the engine will
then crank and start.
2. Move switch to AUTO position. The engine will
start when the load demand circuit senses a need
for current. This occurs after the bilge blower
starts Mid finishes its cycle. The plant will stop
when there is no load on the AC line.
3. Move switch to STOP position. The plant stops.
If stop circuit fails, close fuel valve.
The built-in emergency relay shuts down the plant for
these conditions:
1. Engine fails to start. The engine will crank for ap¬
proximately 90 seconds before the emergency relay
shuts it down.
2. Low oil pressure
3. High water temperature. The engine will stop, start
cranking again for about 90 seconds, then stop, and
not attempt to restart.
To reset the emergency relay, remove the cause of the
emergency, then push the red RESET button on the
Control-O-Matic front panel.
The bilge blower may be connected to the Control-O-
Matic in two ways, Fig. 15 shows the bilge blower
connected to the Control-O-Matic. The blower oper¬
ates from the electric plant cranking batteries. The
B+ and BB terminals are labeled in the Control-O-
Matic Box. With this circuit, the running current of the
blower must not exceed 5 amperes. The user may add
switches as shown to operate bilge blower without
operating the electric plant
In the circuit shown in Fig. 16, an auxiliary relay is
used so that the bilge blower can operate from a sep¬
arate battery or power source. A larger blower may be
15

Figure 15. Bilge Blower Wiring Circuit
used, as long as the relay has a 12 volt DC coil and
the relay contacts can safely carry the current needed
by the blower.
The bilge blower circuit may be disabled so the plant
can be started without delay. This requires changing
one wire connection on the thermal delay relay, mount¬
ed on the inside bottom of the Control-O-Matic box.
Fig. 17 shows this relay actual size. Take care with
the following step, as the terminal posts can easily
be broken. Lift the clip from the rear terminal post of
terminal 1 and place it on the rear post of terminal 3.
With the front-mounted toggle switch in the "AUTO”
position, the plant will respond immediately when the
automatic demand control senses a load. The bilge
blower will run.
The Control-O-Matic shcfuld not need attention, but if
it does not function properly, see the Trouble-Shooting
section for repair procedures.
Figure 17. Disabling Bilge Blower Circuit
Figure 16. Auxiliary Relay Bilge Blower Circuit
16

ADJUSTMENTS
CHECK BREAKER POINTS
Refer to Figure 18 for correct gap distances. Replace
burned or faulty points. If only slightly burned, dress
smooth with file or fine stone. Do not use emory paper
or emory cloth. Measure gap with thickness gauge; gap
points at .020”.
Ignition breaket points, Fig. 18,must be correctly gap¬
ped. Crank engine to fully open breaker points (1/4
turn after top center). Loosen locking screws and turn
cam to adjust. Tighten breaker points and re-check gap.
Ignition points should break contact just as the 25°timing
mark aligns with the flywheel timing mark. Final timing
is corrected by properly shifting the breaker point box
on its mounting and using a timing light. If specified
timing cannot be obtained by positioning the breaker
box, make sure timing marks on gears are aligned.
Timing procedures are described in the MCCK Service
Manual, No. 927-355.
CARBURETOR
The carburetor (Fig. 19) has a high-speed main fuel
adjustment (needle A) and an idle fuel adjustment (nee¬
dle B). The main adjustment (needle A) affects opera¬
tion under heavy load conditions. Idle adjustment af¬
fects operation under light, or no load. Under normal
circumstances, factory carburetor adjustments should
not be disturbed. If the adjustments have been disturb¬
ed, turn needles off their seats 1 to 1-1/2 turns to per¬
mit starting, then re-adjust them for smooth operation.
Caution: Forcing the needle against its seat will dam¬
age it. The needle does not completely shut off when
turned fully in. _____
Before final adjustment, allow engine to warm up. Make
idle adjustment with no load connected to the generator.
Use a tachometer, or connect a frequency meter to gen¬
erator output to observe speed or frequency. Slowly
turn idle adjustment out until engine speed (or genera¬
tor frequency) drops slightly below normal. Then turn
needle in until speed (or frequency) returns to normal.
To set main fuel adjustment, apply a full electrical load
to the generator. Carefully turn main adjustment screw
in until engine speed (or output frequency) drops slight¬
ly below normal. Then turn needle out until speed (or
frequency) returns to normal. Proper carburetor adjust¬
ment cannot be assured unless the governor is proper¬
ly adjusted.
Set throttle stop screw (located on carburetor throttle
lever) with no load connected while running at rated
speed. Turn the screw to give 1/32" clearance be¬
tween the screw and pin (Fig. 19).
Figure 19. Throttle Stop Screw Adjustment (Spec A)
17

Beginning with Spec B, a Zenith carburetor is used.
The carburetor adjustments are the same as the orig¬
inal carburetor. The only difference is the location
of the adjustment needles (Fig. 20). The high-speed
adjustment needle A is on the bottom of carburetor.
Figure 20. Throttle Stop Screw Adjustment (Spec B and later)
To check float level, remove the entire main fuel ad¬
justment assembly from the float bowl (unscrew large
nut from float bowl (Fig. 21). The proper level from
the float to the carburetor body is 1/4”. The float
tab should just touch fuel inlet valve and not compress
the inlet valve spring. Adjust by bending the tab on
the float.
NOTE: Do not apply excessive pressure to float valve.
BEND TAB
A9i3»«* INLET VALVE SPRING
Figure 2 1. Setting Float Level
OMAN THERMO-MAGNETIC CHOKE
This choke uses a heating element and a heat-sensi¬
tive bi-metal spring to open the choke plate. The
choke solenoid, actuated during engine cranking only,
closes the choke plate according to ambient tempera¬
ture.
If adjustment is required, use the following instructions.
Bi-metal choke spring must be at ambient temperature.
Allow engine to cool at least one hour before setting.
Adjust choke by turning the choke body, which engages
a link connected to a bi-metal choke spring. Remove
flame arrestor and adapter to expose the carburetor throat.
Loosen the screw which secures the choke body. Rotate,
choke body clockwise to increase choke, and counter¬
clockwise to decrease choke action (leaner mixture).
Refer to Fig.22 for correct choke settings at various
ambient temperatures. Use drill rod or the shank of a
drill bit to measure the choke opening (Fig. 22).
GOVERNOR
The governor and vacuum booster control engine speed
(Fig. 23). Rated speed and voltage appear on the name¬
plate (also see Specifications). On a 4-pole generator,
engine speed equals frequency multiplied by 30. Thus
1800 r.p.m. gives a 60-cycle frequency and 1500 r.p.m.
equals 50-cycle frequency.
Preferred speed varies approximately 2-1/2 cycles from
no-load to full-load operation. Be sure throttle, link¬
age, and governor mechanism operate smoothly.
Linkage: The engine starts at wide open throttle. The
length of the linkage connecting the governor arm to the
throttle arm is adjusted by rotating the ball joint. Ad¬
just length so that with the engine stopped and with
tension on the governor spring, the stop screw on the
carburetor throttle lever is 1/32” from the stop pin.
This setting allows immediate control by the governor
after starting, and synchronizes travel of the governor
arm and the throttle shaft.
Speed Adjustment: With the plant operating at tempera¬
ture and no load, and with the booster external spring
disconnected, adjust the tension of the governor
spring. Turn the speed-adjusting nut to obtain a volt¬
age and speed reading within the limits shown.
Sensitivity Adjustment: Check the voltage and speed,
first with no load connected, and again with a full
load. Adjust the sensitivity to give the closest reg¬
ulation (least speed and voltage difference between no
load and full load) without causing a hunting condition.
To increase sensitivity (to get closer regulation), move
the governor spring toward the governor shaft. An ad¬
justment for too much sensitivity will cause alternate
increase and decrease of engine speed (hunting).
To decrease sensitivity, move the governor spring
toward the outer end of the governor arm. Too little
sensitivity will result in too much difference in
speed between no-load and full-load conditions.
Any change in the sensitivity adjustment usually re¬
quites a compensating speed (spang tension) adjust¬
ment,
18

VaciMia-Booster Adjustment: After satisfactory perform¬
ance under various loads is attained by governor ad¬
justments without the booster, connect the booster.
Connect the booster external spring to the bracket on
the governor linkage. With the plant operating at no
load, slide the bracket on the governor linkage to a
position where the external spring is just free from
tension.
Apply a full rated electrical load to the generator. The
output voltage should stabilize at nearby the same read¬
ing at full load as for no-load operation. The speed may
remain about the same, or increase when the load is
applied, resulting in 1- or 2-cycle frequencies higher
than the no-load frequency. (1 cycle is equal to 30 rpm
for a 4-pole generator.) If the rise in frequency is more
than 2 cycles, lessen the internal spring tension. If
there is a drop in frequency, increase the booster inter¬
nal spring tension. To increase tension, pull out on the
internal spring bracket and move the pin to a different
hole.
With the booster disconnected, a maximum drop of 5 cy¬
cles from no-load to full-load is normal. Witli the boost¬
er in operation, a maximum increase of 2 cycles from
no-load to 2/3 load is normal. A drop of 1 cycle at 1/4
load is permissible, giving an over-all maximum spread
of 3 cycles.
AMBIENT TEMP. <°F)
60
65
70 75
80
85
90 95
100
CHOKE OPENING (Inches)
l/B 9/64
5/32 1 1/64
3/16
13/64
7/32 15/64
1/4
-CHOKi OPENING
(Set »*xt)
- //V
r \
CHOKE PLATE
Gi — iCi
N ^-LOOSEN THIS
- H i
SCREW AND
— - Hi
f ROTATE THE
-o
ENTIRE COVER
ASSEMBLY
Figure 22. Thermo-Magnetic Choke Adjustments
INTERNAL SPRING-
BRACKET f—
VACUUM
BOOSTER-
THIS
DISTANCE
DETERMINES
SENSITIVITY
| 1
I MORE
| SENSITIVE [
L LESS i
SENSITIVE i
CARBURETOR
THROTTLE ARM-
CARBURETOR
THROTTLE
PLATE—V _J
MOUNTED ON TOP GOVERNOR
ON SPEC “B” LINKAGE-
AND "C”
-GOVERNOR
SPRING BRACKET
V GOVERNOR
_. JXi SPRING
-EXTERNAL
SPRING
‘GOVERNOR
ARM
GOVERNOR
SHAFT
-SPRING
ADJUSTING STUD
GOVERNOR ADJUSTMENT
Figure 23. Governor Details.