Onan MJA Series User manual

1
MJA CONTROL WIRING DIAGRAM
(No low oil pressure Circuit)'
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INTRODUCTION
Tbis manual contains information for proper maintenance,
servicing and overhaul of MJA, MJB, and MJC series
electric generating plants. It doesn't include installation
and operation instructions. Unless otherwise stated, these
instructions apply to all standard plants of the MJA, MJB,
and MJC series. Some details may not apply to special
models with modification specified by the purchaser. How-
/'i.
ever, by using the instructions and recommendations given
in
tbis manual as a general guide" the MJA, MJB, or MJC
generating plant can be properly maintained and repaired.
You will, of course, be using tbis manual primarily for
reference when servicing MJA, MJB, and MJe generat-
ing plants. Tbis is what it was designed for. But, inaddi-
tion, ONAN recommends that you study the whole manual.
It will help to acquaint you with the plants you'll be work-
ing on and save time later on in servicing.
,If possible, use a parts catalog with the service man:ual.
The
parts catalog will give you a good picture of assembly
and disassembly and help identify plant components. Since
the
fir st and most important part of repair work is correct
diagnosis of the trouble, trouble-shooting charts are in-
cludedtbroughout tbis manual to aid diagnosis. Because of
the
variety of engines, generators, and controls discussed
in tbis manual, some sections don't applyto all models. If
.a section or paraf'.'aph applies only to certain models, tbis
is statedat the bf j.nningof the section. Check tbis before
t"l
beginning repair -
,)
Throughout
./
this manual, the flywheel en4 of the enginewill
be
called the "Front" and the fuelpump'side designated the
"Left Side".

.~
IONAN'MODElNUMBERING -SYSTEM'
YYPICAlMODEl: SMJB.1R/96B
MOOU- "SMJB~l R /968
TiTTiT~
S.EENOTE- 1 2 3 4567
NOTE
1 - Plant Capacity in Kilowatts -For Example.: 3 -3KW
30.5 -3. 5KW
5 - 5EW
;-:;.,
2 -Plant Ser ies
3 - 60 Cycle
Electrical .output
No. of
Code
Volts
Phase
Wires
1
120
1 2
2
240 1 2
3-*
120/240
1 3
4 120/2.08 1 3
~5
240
3 3
5D (delta)
120/240
3 4
50 added to code designates 50 cycle i.e. 1 becomes 51.
4-Type ·of Starting-R- RemoteE -Electric M- Manual
'S - Diagonal Line - Separates Basic Model from Specification Number
and Letter.
6 -Specification Number - Denotes Customer Requested Deviations
from Standard Model.
'1-Specifica'tif)fl Letter - Advances .with ONANchanges.
* -,5M:JB -- Some models have generators reconnectib1e for either
code 1, 2, or 3; these models are designated 3C.
-'705
MJB & MJC --AlICode .3 models are reconnectible for either
code 1, .2, or 3, See the plant operators manual
V"'''.ALN .. J.h J:!.A\;;!lJ:!:<.J'tW :Ut1.DlV J.)U\,\,;rJ:tAlVl
Used on705MJB Spec A and Spec B.
625C292 I02.5XINI,
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V'!.L 5£ I:!NT'OP OF t:AC:H!1-EIH

3
Q4SXINIB and 06SXINIB EXCITER WIRING DIAGRAM
06SX Spec B Static Exciter Wiring Diagram
in Pictorial (With residual reset switch)
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04SX Spec B Static Exciter Wiring Diagram
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TABLE OF CONTENTS
SECT.
INDEX .................................•........
1.
GENERATING PLANTS (Early models shown) ..... "
2. PERIODIC SERVICE ...................•........
3. THE ENGINE •................................•.
3. 1 Cooling System ............................ .
3.2 Fuel System ..............................•..
3.3 Ignition System ...................•.......••.
3.4 Governor System ........................ ~ •..
3. 5 Oil System ..............................•.••
3. 6 Starting System ............................ .
3.7 Cylinder Heads and Valves ••................•
3.8 Pistons, Connecting Rods & Cylinders .•.......
3.9 Engine Disassembly ........................ .
4. GENERATOR, REVOLVING
FIELD
(705MJB, MJC) ............................... .
5. GENERATOR, REVOLVING
FIELD
(3MJA, 4MJA and 5MJB) •.......................
6. CONTROL SYSTEM
............................. .
7. ASSEMBLY TORQUES
........................... .
8.
SPECIAL TOOLS .............................•...
9. TABLE
OF CLEARANCES & DIMENSIONS .••......•
10.
~G DIAGRA~ ..................•..........
Trouble Shooting Charts
PAGE
1. The Engine. . . . . . . .. 11
2. Cooling System .. . .. 26
3. Fuel System ....... 40
4. Ignition System ... . . 54
5.
Governor System ... 59
6. Oil System ... . . . . .. 64
7. Starting System .... 71
8.
9.
10.
11.
12.
Cylinder Head and Valves
Pistons, Connecting Rods
and Cylinders. . . . •• ••
Revolving Field Genera-
tOr ••.........•.... ~.
Magneciter •...•......
Revolving Armature Gen-'
erator.... .. ...... .....
PAGE
4
6
9
10
19
28
41
57
60
66
73
80
85
93
109
119
128
129
130
133
PAGE
78
84
105
107,
117

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4:
INDEX
SUBJECT
Ai? Silencer
Anti-Flicker Point Set
Armature, Generator
Automatic Choke
Back Pressure, Exhaust
Batteries
Battery Charging
Rev. Armature Models
Rev. Field Models
Battery Charging Rectifier
(Revolving Field)
Battery Charging Resistor
(Revolving Field)
Battery Polarity (Rev. Field)
Bearings, Camshaft
Bearings, Connecting Rod
Bearings, Main
Break-In Period
Breather Valve
Camshaft
Bearings
Center Pin
Gear
Carburetor, Gasoline
Centrifugal Switch
(Start-Disco,nnect)
Choke, Electric
Compression Rings
Connecting Rod
Connecting Rod Bearing
Control System
Cooling
Crankcase
Crankcase
Breather
Crankshaft
Bearings
Gear
Removal
Cylinders
Cylinder He.ad
Distributor
Electric Starting
Emergency Relay
Exciter Cranking
ExballS~ Back Pressure
Flyballs
Flyball Governor
SECTION
3.2.6
5.1. 4
5
3.2.4
3.2.7
3.6
6.2.2
6.3.2
6.3.2.1
6.-3.2.2
6.3.2
3.9.4.4
3.8.7
3.9.5.4
3.8.9
3.5.7
3.9.4
3.9.4.4
3.9.3
3.9.4.3
3.2.5
6.3.1.3&
3.3
3.2.4
3.8.5
3.8.6
3.8.7
6
3.1
3.9.6
3.5.7
3.9.5
3.9.5.4
3.9.5
3.9.5.1
3.R.2
3.7
3.3.4.3
3.3
6.2.3.2 &
6.3.3.4
5
3.2.7
3.9.3
3.4 &
3.9.3
SUBJECT
Flyball Spacer (see
camshaft gear)
Fly.vheel
Fuel
Fuel
Pump
Fuel Strainer
Gasoline Carburetor
Gear Cover
Generator Blower
Generator Brush Rig
Governor
Governor
Arm
Governor Cup
Governor Linkage
Governor Shaft
Governor Shaft Bearings
Governor Spring
Governor "Thrust Ball Brg.
Governor Yoke
Heat Exchanger
Hi- Temp. Switch
Ignition
Breaker Points
1 Cylinder
2 Cylinder
4 Cylinder
Ignition Coil
1 Cylinder
2 Cylinder
4
Cylinder
Ignition Condenser
1 Cylinder
2 Cylinder
4 Cylinder
Ignition
Latching
Low Oil Pressure Switch
Revolving Armature
Revolving Field
Magneciter
Reactors
Rectifiers
Residual Re-Set Switch
Needle Bearings, Governor
Shaft
Oil
BY··.:;:'c.]8 Valve
SECTION
3.9.1
3.2.1
3.2.3
3.2.2
3.2.5
3.9.2
4
5
3.4&
3.9.3
3.4
3.9.3
3.4
3.9.2.1
3.9.2
3.4
S.9.2
3.9.2
3.1.4
6.2.3.1 &
6.3.3.1
3.3.2
3.3.3.3
3.3.4
3.3.2
3.3.3.5
3.3.4.4
3.3.2
3.3.3.4
3.3.4.5
6.3.1.2
6.2.3.2
6.2.3.2
6.3.3.2
4.2.3 &
4.3.3
4.3.3.1
4.3.3.2
4.3.1.1
3.9.2
3.5.3
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MJC CONTROL WIRlNGDIAGRAM
5"
(With
low oil presSure circuit)
INDEX (CONT)
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SUBJECT
Oil Control Rings
Oil Filter
Oil Grade
Oil Lines
Oil PreSSUIe Gauge
Oil
Pump
Oil Pump Intake Cup
Oil Seal, Crankshaft Rear
Oil Seal, Gear Cover
Oil Seal, Governor Shaft
Oil Seal, Valve Stem
Oil System
Periodic Servicing
Pistons
Piston Pin
Piston Pin Bushing
Piston Rings
Place Bolt
Preventive Maintenance
Rear Bearing Plate
Reconnection Block
Remote Starting
Revolving Armature
Revolving Field
Residual Reset Switch
Reverse Current Relay
Revolving
Armature Gener-
ator
Armature
Ball Bearing
Brushes
Commutator
Field
Commutator
Collector Rings
Resistor (Charge Circuit)
ReSistor (Emergency CirCuit)
Revolving
Field Generator
Air Baffle
Battery Charging Winding
Brushes
Bearing
EXCiter
Rotor
Collector Rings
SECTION
'3.8.5
3.5.6
3.5.1
3.5.4
3.5.5
3.5.2
3.5
3.9.5.5
3.9.2.2
3.9.2
3.7.5
3.5
2
3.8.3
3.8.4
3.B.6
3.B,5
7
2
3.9.5
6.3.2
6.2
6.3
4.3.1.1
6.2.2.1
5
5.3,1
5.1.2&
5.3.5
5.1.1
5.1. 3 &
5.3.3
5.3.2
5.1.3
5.1.3
&
5.3.4
6.3.3.2
6.3.3.5
4
4.5,
4.3.2.3
4.2.1
4.2.2
4.2.3
4.3;2
4.2.4&
4.3.2.4
SUBJECT
Stator
Ring Gear
Rocker Arm
Rocker Box Cover
Rocker Box Cover Oil Line
Run-In Period
Solenoid Shift Starter
Spark Plugs
Start-:-Disconnect Relay
Start Ignition Relay
Starting Motor
Starting System
Start Solenoid
Static Exciter (see Magne-
citer)
Stop Relay
Thermostat (Coolant)
Thrust Washer, Camshaft
Thrust Washer, Crankshaft
Valves
Clearance Adjustment
Guide
Push Rods
Seats
Spring
Spring
Retainer
Spring Retainer Lock
Stem Cap
Stem Oil Seal
Tappet
Water Pump
Wrist Pin
SECTION
4.3.2
3.5.1.1
3.7.5
3.5.4
3.5.4
3.B.9
3.6
3.3.5
6.2.1.3
6.3 .. 1.1
3.6
3.6
6.2.1.1&
6.3.1.4
6.2.1.2
3.1.3.1
3.9.4.5
3.9.5.6
3.7.4.1
3.7.1
3.7.4.2
3.7.5
3.7.4.3
3.7.4.4
3.7.3&
3.7.5
3,7.3 &
3.7.5
3.7.3 &
3.7.5
3.7.3&
3.7.5
3.7.3
3.1.3.2 &
3.1.4.5
3.8.4
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7
705MJB CONTROL WIRING DIAGRAM
(With low oil pressure circuit)
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MODEL MJB-LEFT FRONT VIEW
THERMOSTAT HOUSING
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EXHAUST MANI
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MODEL MJB- RIGHT REAR VIEW

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STRIP
M/(!TK
£.R
STRIP
TO
GENERATOR
• I
START£R
t
I
I
I
I
I
I
I C
·
·
(
·
·
,
,

9
,.-
I
5MJBCONTROL WIRING DIAGRAM
(With
low oil pressurecircuit*)
-' r<
* -Beginning with
~~ ~i
Spec F Models
.5 0 lC ...
A -' <ill
... 1Il :>:
r
it· ~ I!
II ~ II
:~' ;: II r----.
j"';jIIHI' t Ir
jlr-~ jl I ,t ~~
1 U'l I J ,---- - -' i=~
1 ',11' 'riP i7"
,_J .. _.Jll_ rl "'~
:l - .-- 11
7 "
.. 1\1) """'u
~:! II m~ ilE~~ ~
- 0 11 OOGO): !>:"'o
~" IL _ -,:,,,,:'''
1- Li---
1'
I.,;
'1; \ B.
)
0 "'0
;: lo:z
1- 0"
:z ......
'" <;"
I';\il
~CI:'
~i ~F~
l~? ~ ~ ~
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....
:
l:u ""'
14 VI V)
r<-
-;t
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....
JL 3-
I
~
..iii
u'-<
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rei
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I,I!:;O
2. PERIODIC SERVICE CHART
Use the following chart as a guide to servicing requirements. Remem-
ber, neglect of routine servicing could cause plant failure when it's
urgently needed .
The chart is based on units operating under favorable conditions - pro-
per installation, recommended fuel and oil normal load ... If the operat-
ing conditions are unfavorable, adjust the service periods accordingly.
PERIODIC SERVICE CHART
SERVICE
AFTER EACH CYCLE OF INDICATED
THESE
HSJURS
SEE
ITEMS 8 100 200 500
lOOO
5000 SECTION
Inspect Plant Generally x
Check Fuel Supply x 3
2.1
Check Oil Level x
3.5.1
Clean Governor Linkilge. I it 3.4.1
Service Air Cleaner (Silencer)
xt
3.2.6
Change Crankcase Oil
"'
x
3.5.1
Clean Crankcase Breather
x
3.5.7
C,ean and Adiust Spark Plugs'
x
.... -
_3.~
Check Breaker Paints x
3.3.2
3.3.3
. _.
f-- ..
3.3.4
Check Battery Electrolyte
Level
x
Empty Fuel Sediment Bowl x
3.2.2
Check Valve .Clearance
•
I··~
Inspect Generator Brushes
x
4.2.1
5.1.1
Inspect Water Pump Impeller
3:~
(Neoprene)
x~
f-- .. -
3.1.3.2
Crean Build-up Relay Contact
J02SX MagIleciter Onlv) x
4.2
Replace Oil Filter
~ l(
3.5.6
Clean Carburetor
x 3.2.5
Clean Rocker Box Oil Line
Holes
-I- . x
..-
_ 3.5.4
, Clean Combustion Chamber
x
3.2.1
3.7.1
... -
Grind Valves
x
3.7.4
Clean Generating Plant
x
Complete Reconditioning x
t Service more often under extreme dust conditions.
"' li engine is operating in extremely low temperature; for short operating periods;
with highly lea!=led gaSOline; or in extremes of dUst and dirt,
100 hours instead of every 200 hours.
then change oil every
. .
.oL Change tlJe filter more often if, because of freezing temperatures or extreme dUst
conditions, the oil
becomes 50 black and dirty the markings on the level indicator
can't be seen through the Oil.
• Tighten head bolts and adjust valve clearance after £irst .~O hOurs on anew or
overhauled engine.

3,. 'THE ,;ENGI,NE
The generaHngplants in this manual use a 4·.strokecycle, vertical in.line, valve in h€ad,'
spark ignition, gasoline fueledengir,ewitha cooling system Di the pre'ssure 'circulatingliquid
cooled type.
in au .cases,l..hespeed is governor controlled at 1800 rpm for 60 cps output generating plants.
same manual'because 01 the
great similarity between them. Unl"ss otherwise .specified,
One, twO, and lour.cylinder generating planlsare included in
instructions and .procedUres
apply.LD one, two,
and four cylinder·engines.
NOTE: All dimensions,clearances, and wear limits are inclu'ded in Sect 9,
ENGINE DATA
Model Series
Number cylinders (vertical in-line) ....... .
Displacement {cubic inch} ..........•.. , ..
Cylinder bore ..•....................•...
Piston Stroke ....................... , .. .
RPM {for .60 ~ycle} .............. , ...... .
Compression ratio 6.5 to 1 for gasoline
(uel ., ................ ' ............. .
Exhaust connection (pipe .tapped) ....... , .. .
SteUite faced exhaust valve (s) .. , , ..... , ..
Valve ·rotators on intake and exhaust ......
Connecting· rod bearings arelri-rnetal
replaceable ............. " ... ,... ....
oMain bearings ·are leaded bronze; precision
type lor replacement {quantoity used) .....
Battery ignition .... , ............ , ......
Battery voltage lac plant) ... ,.. . .......
Battery size (ac plant):
,705
MJB ilOMJCIl5MJC
ISMJ8
yes
yes
yes
2
yes
12-v
4 4
60
2
2
120 120
3-1/4
60
3-1/4 3-1/4
3-5/8
3-1/4 3-5/6
1800
3-5/8
3-5/8
1600
1800 1800
yes yes
1-1/4
yes
yes
1-1/2 1-1/2
yes
1-1/4
yes
yes
yes
yes yes
yes
yes
yes
yes
yes
yes
3
yes
3
2
2 ·yes
yes
'yes
12-v
12-v 12-v
12-v
two in
sertes
two in
two in two in
series
105
.series.
series
165
105
105
5 MJBGONTROLWffirnG:DlAGRAM
low· oHpressure:ctrcmt*)
"
~ E:~-!
'" It< .(
i 3'~~~
'" I ~-.-:-~:
., r'------ - . -1" :;z.;sX
::\ '--r-'-~-'
"'II __ ~ 1
-..
Il'
* -Priorto SpecF
Models
e
"
"
'"
"
.,
z,
'"
<r
~
't,
~
\9
~ -
<Tn
Jo"
~~(
<- ..
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1i~1l
:1 ~
~~~
;"~~
.:r:i('.g
I
~~~
• Ai,),
. .. .,
I .
L_
,..
.. - ~ ..
... ..
'0,",
.:0
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'1
-1
I
1
[.
I
It JL J, ~ .• ~
l
u.. ~~
l~~ :tv
ell
,,<
z..
%0
S:l
lh
~"
:;:4
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I
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h
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I
," I')
.... -
fO+
I t
--r I~!J~ ",
I . , e~"
. ~,~
. m'm:
a~
~ll'~
~~ll
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o (1)(1)
,l> ::x:: ...........
!'il!:;!:1<;";"
.~ ·0(1)(1)
o (1) >1!':l~'Ul
Z
:~ 10 .tl!C
....<t> ..... ,c ....
____ .,.;.1
~
e~ \;
-0·0 :".
-18~ ."
..
~~ -:
~~r:
\""'~
, , .
xx. ~
IL" %
;~-:~
0 0 -0(
(\Jilt .•
r-!" t
.t:~ .. ~ .
uU ...
.... -
p;-fI- r,%
:~~
:~ e
iJ e;~ ..
t:i~li .. it>
:!liJlfl"
~
°0
-1
,0
,..
i
O'l:lIoi4'
SAEgroup 1H ....•....... , .......... I two in
series
Amp/hr. SAE 20-br (nominal) '" .... .
105
Water cooled exhaust manifold ., .. , ..... '
,Drip pan and rnolded vibration mounts •... ,
'!MaXimuIDr-ecommended
power take-_of! £1'
front 'pulley at any load . , .. .., ... , ... ,.
Pewer take-oi! limit at rated load .. , .. ; ..
2
High temperature cut-on ., ... , ......... .
'Total cu. fl .. per min. oLair requi1led ., .. .
Genera.torcooling air (CFM at 180'0 rpm) "
Combustion air.{CFM,at 1800.rpm) . , ..... .
Alr cleaner flame arrester .. , ... , . , .•
Crl1Jk£·rfar .gasolllle fuel ,.
yes
yes
1
yes
Starting by exciter cranking .......... , .. .
yes
yes
yes_ 'yes
Startingl.!y solenoid shift starting mOlar .. . no
nO
nO
Centr.ifugal Start-Disconnect Swltch .... , ..
not
no •• no
yes
,2
yes
not
2
2
Batter.y charge rate amperes (normal) .. , ..
2
5~0-5
5.0-5· 5-0-5
-Oil Capacity in U ,S. quarts (refill) , .... , .
2.5
5-0'-5
Charge ammeter scale .,....... . ..... '
5-0-5
3 6
Cooling water flow (gallons per minute) , ..
4 3 6 4
yes
4
4
4
yes yes
yes
yes . yes
,2 hp
2hp
1 hp
2hp 2hp
yes
2hp
lin
120
1'1
120
180'
3f>
35
dry
ele·c·
dry
dry
elec-
tric
elec-
tric
8
tric
8
8
-l - ,Centrifugalswitch is used with safety cut-aU buLnot for start-disconnect.
.• _ Plus l!2quart for new fil~r .
i. - Beginning with SpecF; •• - Prior to Spec F.

---
11 TROUB LE -SHOOTING CHAR T
5MJB CONTROL
WIRING DIAGRAM
(No low oilpressure circuit *)
..
~"
'2 v It.
J i
..
* - Begin Spec F
:;.~ ~
- 0 ~
Models
~ ItJ "
'" ~
I- ~
j-1-
--,
I
I
I
,
~~
h
""' .....
,1.,1...10
~~~~
-
'Ii
~~~~
QftllP
...
'"
~
0
t-.
';(
oil::
~~
1U
I.!)
I(
:~r"" ie ~J
~, ,-: ~~ ;...;...
" 0 ~'''''''''
Pil~_ (]) (])
j.',' E-<(])~LP;Ul
~~I~
-~U----_..J
OUl'0..c'US::
I Z!::>m ..........
I
I
L
"',
ji-E'
" -
., '"
- ...
:; IX'
I'
"
t- (;
ttx
<( ...
I- -'
oJ) "
~
-'
w
'"
"
"
!;;
--,
I
~
'
,
I,
I /:.
.,
~
..
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'"
:z:li
,,:.
~%
",I':
-~
s~
g
;Irt
..
I-U
z
~:z:
,,~
,,-
... ~
...
1 l!
~~
2·
i~
'"
..
:l
11,0-
II ~
II ~
k
...
/-\ii'~
I l'It;"
\ , Ii J:
'-- ;;II'
r:
z
;;
ii
..iii
v ....
x",,
coo
dl
.,J
~ J
.. 0 .........
~~~'~~:
cJ Z"''I,)IJ.
~ cit I
~ ~
0( 0
Il- .dSuUHJl).)
"
0
TROUBLE-SHOOTING CHART 1, THE ENGINE
TROUBLE
Engine will not
crank
I
Engine cranks
too
slowly
Engine cranks but
won't start
Water in fuel. Replace fuel.
I -
REMEDY
POSSIBLE CAUSE
Battery discharged.
See Trouble-Shooting
Chart 7.
Control circuit defective.
See Sect 6.
Internal seizure. Disassemble engine
and repair.
Engine oil too heavy for
See Sect 3.5.1 for oil
operation in low temper- recommendations.
ature .
Defective connections be-
See Sect 3.6.2.
tween battery and starter.
!
REVOLVING ARMATURE
GENERATOR
(Exciter
Cranked)
Poor brush contact on See Sect 5.
generator.
SEP ARA TE STARTING
MOTOR MODELS
Starting motor de- See Trouble -Shooting
fective. Chart 7.
Oil in crankcase too
See Sect 3.5.1 for oil
heavy
for low temper- recommendations.
ature.
Discharged battery.
See Trouble-Shooting
Chart 7.
Corroded battery con-
See Sect 3.6.2.
nectj Jns or defective
battery cable.
Fuel system faulty.
No fuel in
tank. Refill tank.
Clean filter Sect 3.2.2
Filter screen clogged.

'"
.l.~
..&.,1\. U.LJ'.,LlLol -l,J.l...L,,-,,-,.L .LJ;-. ,"",', V .L,I. ..... ,.s.\,. .L
TROUBLE-SHOOTING CHART 1, THE ENGINE (Cont.)
TRO BLE POSSIBL A SE
RElVIE
Fuel system faulty (Cont.)
Engine cranks but
No gasoline at carbure-I See Trouble-Shooting
won't start (Cont.) tor. Chart 3.
<::
...,
:i
'"
If,
~~
0-
'!!~
::;1'
:t'
0 6
,,<
..".
r'l
~3
" ...
".:
u
lVJ.cJ.,n. \o.,..VJ.)I.t nv..l...t_ VY~_n.1l~,V .t..U:fiU'..n...t1..tV!
lUI
II
(With low oil pressure circuit)
[-]
,.
0(
~
'"
lfh~
~ -
Q
'''0
liZ
«",
t-
J
"'.,
'"
I ~
(:N
r
.-
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o~
'r
"'''-
r::r
I
Sre.c Ii. oit/y
-,
I
~1
I
~
...
..
'1;
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<:
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a:
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:lu~ ~ ~)()(
~
:z ..
~~
~~~ r~~'" ,: ~~
ltl ..Jo~" _
~ od). Q "
!3..J~~C-::;
.... 0 D:!t-
'J J~a~~:!i ~I
~~ e~':'eg~
';::- ~u~t:~,~
n:! U' >')(::L:;:>'
~ ~~o~:i~
t: Q.dJV
--..::...=.=.."$I
--+..)+
',,.J1,,.i •
Il.~~ ~
I
:·,; "~
N~ ':.t:.
-"'fOHt
l
UlUl
(1)(1;)
o ::t: ...... ,.,.
M ::e .......... ~ ~
.................... (1) (1)
~ (1)~LDZ Ul
o ttl IO'C\j,t::
Z ::>(.0 _ ~ .,;.;
Defective fuel pump.
Ignition system faulty.
See Trouble -Shooting
Chart 4.
Carburetor choked too Check choke adjust-
much.
ment Sect 3.2.4.
Air intake restricted.
Clean air cleaner
Sect 3.2.6.
Exhaust system clogged. See Sect 3.2.7.
Poor compression. See Trouble-Shooting
Chart 8 and Sect 3.7.2
Poor fuel. Change fuel.
Wrong timing.
Retime.
Engine flooded. Correct operating pro-
cedures or adjust
choke.
Engine hard to
Restricted air intake.
Clean ail' cleaner
start
Sect 3.2.6.
Poor fuel.
Change fuel.
Defective ignition sys-
tem. See Trouble-Shooting
Chart 4.
Incorrect timing.
Repair or replace fuel,
pump - For tests see
Sect 3.2.3.1.
Defective fuel pump.
Poor compression.
I See Trouble -Shooting
Chart 8 and Sect 3.7.2
I
I
I

MJA CONTROL WIRING DIAGRAM
(No low oil pressure circuit)
Spec: Ao'Jt/'l
<", ..
...
...
...
'loJ ..,~
! It
:1.,..t u> ...
-0 x It
~~ 7~
~~ 4(.-
-'" 2%
--.~~
l
<!l :z~ :to
~ d< ~%
I- :;...1..--, _
___ t .. !::'"
~ -w _0
~ Q;
I
po If ~U
f1: r---
I~ !HI'I
I~ t HI.
1
L __ , J
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11.,::\ I,
I'I _- :.:.~ - - - -:- : ~I'
1
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1 ~~
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I
I
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II.
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l-
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'Zit ~""'!!l
, l:tE\I
t-ol-t-!iJ
~Zu251oU
to-SuP:
-llJIt I t a
~:Ct:~~~ UI
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,.. ®
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1- ...
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s~
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e
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;::.....,::t: f.< f.<
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rl~S
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:.c
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x x::i~
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c1.J~~tnl£
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;::
t
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,tt
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g
iii
J:;.l.....,."..< Q) Q)
r.:- -:--- - - ~~- _.l
E-<Q)OIl'.)~1ll
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oro
c:
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zo;:o ..... ..0 .....
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I:;'r:f
~;~
TROUBLE-SHOOTING CHART
TROUBLE -SHOOTING CHART 1, THE ENGINE (Cont.)
1TROUBLE POSSIBLE
CAUSE
I Water in gasoline. IEngine misses
and backfires but i
fails to start Air leaks around intake
manifold. manifold.
Improper firing order (JC).
Ignition
timing incorrect.
r----
Moisture on breaker points
Engine races (stop Too
much fuel caused by: I
engine immediately
Disconnected governor
by pushing throttle
mechanism. '
lever)
Engine stops
Emergency shutdown
unexpectedly
circuit operated.
I
Internal seizure.
To test, crank by hand
disassemble and repair.
Excessive crankcase
Remove and clean
pressure,caused by
breather.
clogged breather.
,--
:
--
Low engine
Restricted air intake.
Clean air cleaner.
jPower High
exhaust back pres-
Check back pressure
sure.
Sect. 3.2.7.
-- -- -_ .. __ ..... _--_ ..... _-
13
RE:MEDY
IChange fuel.
Inspect all gaskets on
Inspect ignition
distributor system.
Retime ignition.
Clean distributor.
Defective governor.
See Sect 3. 4 and
Trouble-Shooting Chart
Incorrect governor
5
adjustment.
Check low oil
pressure
and high air temper-
ature switches, if used.
Vapor lock in fuel line, Allow
engine to cool,
fuel pump
or carburetor.
check for possible over-
heating, Sect 3.1.2
Defective ignition. See
Trouble -Shooting
Chart 4.
I
Lack of fueL
Refill tank.
I

.1.':1:
"""J..,\.,",,UU""-J,&.,;.;-...::;:J.J..l·.V\.J~.Ll.,,(U VJ..l..n..l\'~
.l.V.&.tJ.n.. \...vJ,".J.nvJ,.i Wl·.rtlrt:.U J:,JJ;i\.\:a.tt.a-.lV!
(With low oil pl'essul'e cil'cuit)
S.tin Sp.cD
TROUBLE-SHOOTING CHART 1, THE ENGINE (Cant.)
POSSIBLE CAUSE
TROUBLE
I .
ILowengme
Ipower (Cant.)
I
I
I
I
I
Poor fuel.
Poor compression.
Defective ignition (engine
not firing on all cylinders).
Incorrect
timing.
REMEDY
Change fuel, Sect.3. 2. 1.
Check compression,
Sect 3. 7.2 and Trouble-
Shooting Chart 8.
See Trouble-Shooting
Chart 4.
See Trouble -Shooting
Chart 4.
r,
.~~
--~'~t i•
j
.. ~
g~
§i
s;= ,I"
4"
::..J ........... " ... CiWiiooiii7Uoii)l
~!Z
~ii. I"":... ...... .j ...... "" ~~
"' ............... -1--
11'P:-'l1
~
- .>~!-.~-,~
".
'¢
I
~Q ~~'4i h>,C)Z
f'j
"'''P~
~{)Ii1!
':'iz"'''mop,
' '--I>ln::rrf'l.
... l ::£'._ -n .... -'OAKE.
~
~ ". u~ l"" ""'U).(;- .J._.;.,::
6 I
L~ S 1:;~l"~~~,"~:'I.l'
...,
~s ':,. ~ U?·~ t'i:!;;~~.~~~
W
~ ·ii"p'r£.t-.~
>!l
----'@"
Engine misses
at light load
See Sect 3.2.4.
Improper choke operation.
Clean cylinders, See
Heavy carbon deposits in
Sect 3.2.1.
cylinders.
See Trouble-Shooting
Chart 3 ..
Faulty carburetion.
Spar k plug gaps too
narrOW.
Set at .025.
Intake air leak.
Inspect intake manifold
and carburetor.
Faulty ignition system.
See Trouble-Shooting
Chart 4.
Uneven I.CU.1.1JjJl
;sinn.
See Sect 3.7.2.
Spark plugs defective.
See Sect 3. 3. 5.
Clogged carburetor idle
jet.
Clean carburetor.
Defective high tension
cable.
Inspect and replace if
necessary.
Engine misfires
at heavy load
Spark plug gap too wide.
Clogged carburetor.
Adjust to .025.
. ~-!
Clean carburetor,
3.~. 5.
sect
Clogged fuel screen.
Clean, Sect 3.2.2.

10 TROUBLE -SHOOTING CHAR'T
GENERATOR WIRING DIAGRAMS
TO T£RM. 7. CONTROl.
PO)( T£~MIN"'L PLOCK
T,
n
........-
.-
I..-"";::;;;,;;;;", __ ?_ ~ Ii
b!
7i
A~
"'''TOI\
7"z.
13
7f.
... ,,'~ .. ".. .
t; .. WI .. "'"''
1- ..l'1!1. .uto!f:lr ..... - - - -,
I A.".~o;.l"Q"""W·'" I
"
............ ~,. I" .. AU .• W'.', I
I
flaY ... ' I , .. ,WO"T
I
€:1"', I i!:Ti - --- _. I
tTl. ~----- I !.TL
I ~/ I ~ I
'iii'~_.t __ '1 IiTJ .
I.!::_~_.J I!:'''--J--- I
I tf'''AUllW'~b "1 ! I
IU·hOV •• T I I
I
I
i~~ ----. I I
I ')0- -.1 -- I ·1
JIe'h ~. II
!!( ____ I I
dng Field (3R) Reconnectible for 120, 240 or 120-240 Volts, Single Phase
TO TERM.?,
~. When using a 3-wire system (instead of a CONTROL
80X
4-wire) unground and insulate wire TO.
7EIiMIN,tIL PM";/(
.j"OHP1.I,SQ wI<rr
tin' •.
CHI\/HiINQ
WINOINQ
I>a
Revolving Field (4R) 120-208 Volts, Wye Wound; 4-wire, 3 Phase
10rli:~7
~(lNUOt o,{
~ff/,M5f w.m
Tf,IJM I~ (;"
TROUBLE-SHOOTING CHART 1, THE ENGINE (Cont.)
TROUBLE POSSIBLE CAUSE RE:MEDY
Engine misfires
at heavy load (con
Valve lash too tight.
i.)
Defective ignition sys-
tem.
Adjust lash, Sect 3.7. 1.
See Trouble-Shooting
Chart 4 ..
Engine backfires
Excess oil con-
sumption, light
blue smoky
exhaust
"
Lean fuel mixture.
!---'
Clogged fuel screen.
Adjust carburetor,
Sect 3.2.5.
Clean, Sect 3.2.2.
Poor fueL
Change fuel, Sect 3.2.2.
Spark too late.
Time ignition ..
Leaking intake valve.
Check compression
See Sect 3.7. 2.
Improper firing order
(JC).
Inspect ignition dis-
tributor system (cor-
rect order 1-2-4-3).
Poor compression.
r-~~
Crankcase oil too light
or diluted.
See Trouble~Shooting
Chart 8 and Sect 3.7.2.
Change to correct oil
Sect 3. 5.l. If diluted,
See Trouble-Shooting
Chart 6.
Engine misfiring. See Engine Misfiring,
this chart.
Excess oil in crankcase.
..c.,~
Engine overheating.
Drain to full level.
See Sect 3. 1. 2.
Defective intake valve
stem oil seal.
Replace, Sect 3.7.
~ orn intake valve, guide
or valve stem.
Replace, Sect 3. 7.
Faulty ignition.
-,~
See Trouble-Shooting
Chart 4.
--,~
tevolving Field (5DR) 120-240 Volts, Delta Wound, 4-wire, 3 Phase

"'" .L_ .L.\'- "".' V .1..1. .&...1.&;;,1. - u·,LL '-' .1.- .... ~.L." ""-I '-'.J. ... .c:L~\. .A:
.L·u
TROUBLE-SHOOTING CHART 1, THE ENGINE (Cont. )
GENERATOR WIRING DIAGRAMS
Dull, metallic Loose crankshaft bear-
tlmd, if not bad
ing.
may disappear
after few minutes
,of operation
Sharp, metallic 1 Low oil supply.
thud; especially
when cold engine. Oil badly diluted.
first started.
Tapping sound,
Valve clearance too
clacking; light great.
cliCking
Broken valve spring.
Metallic knock Worn connecting rod
under no load
bearings.
• conditions and
when stopping
I
TROUBLE POSSIBLE CAUSE
Excess oil con- Oil leak from oil base or
sumption, no in- connections.
crease in smoke
I
Leaky crankshaft oil
seals.
Black, smoky ex-
must, excessive
fuel consumption,
fouling of spark
plugs with black
soot, possible
lack of power
under load
Fuel mixture too rich.
Choke not open.
i Clogged air intake.
I
RE:MEDY
Inspect engine, check
for clogged crankcase
breather.
Inspect oil seals, Sect
3. 9.2.2 and Sect 3. 9. 5. 5
Check for clogged
crankcase breather.
Adjust carburetor
Sect 3.2.5.
See Sect 3.2.4.
Clean air cleaner,
Sect 3.2.6.
Replace bearing.
Add oil.
Replace oil.
Check valve clearance
Sect 3.7.1.
Replace valve spring.
Replace bearings.
TO CONTitUL BO}(
i M:2. • M2..
TO_L.OAD
~I
Fa
+ \,1/
·ARMATU·RE:
e ~M'
~'i
.-A.-C::SLI p /I
... 'RINGS:~ ~:.L~"IT.CONC:
4MJA Revolving Armature. 2-Wlre, Single Phase
TO CONTROL BoX
')("! n
LOAP
Pc..
SI
TO
·M.2.
4MJA Revolving Armature 3-Wire, Single Phase
£2
ReSIDUA!..' GI
RE..SET _. I r-.1 -"';-1'----
.sW/T..cH_ I ,
t7c~;.::.:J-: I II
~:gJ~ rli I
O""y)~.t-l I
REAC"fDR -;..'
STABILIZING.
RES/STOR
u
:: Ll---~--·~-l Lt·-J!:-·-I!:.J F
J2.DV. .... ~£~ : : ti2: C.2LI_s~'~L-=====+- __ ~S~2_~ ,::c'==t=G:::'=;--f£c
i
~ocy. : L _____________ 3 !
~
.,
'----.-;;-
4
-ZcAl..IBRAT£1)_~HUNr
2
:/~t,s:igT..f
DAMPIIJQ ./\£,$IS TOR
El
Loose piston.
,
Check piston clearance.
,Bollow clIcking
• sound with engine
, cool and under
load.
-

17
GENERATOR WIRING DIAGRAMS
ros/ TO' AI .
IN CONTROL BOX IN CONTROI.:eox
J
";Ma
~,
TO I-OAP
Fa
r .. ~
ri tlt" II. ""I
A,C', SLIP RINGdil
lYing Armature 2-wire, Single ~haSe (5MJB prior to spec F, 3 MJA),
TO <>1
TOAI
I"CONTROI..BOX IN COIJTROi.. BOX
J
r-----------------------------------~~~Ma
'r------------------::--~·MJ
FK\"
ARMATURE
TD
~DAc
." MI
:f~2 .. ·.1 ~fP. COI"fP'S,
Iving Armature 3-wire, Single Phase (5MJB prior to spec F, 3 MJA)
. TO Flj
TO AI
IN CONTROL &Jx
___________________ I_W __ C_0.JN[ROL BoX
r • Ml
MZ.
L.OAD·
ARt.1ATURE
-'-)-9
TO
Itt I . .....,. MI
, T¥-.' MFa ,OND.
LA. C. SLIP .RINGS
volving Armature 2-wire, Single Phase (5MJB only, begin spec F)
TROUBLE-SHOOTI CHART
TROUBLE-SHOOTING CHART 1, THE ENGINE (Cont.)
TROUBLE I POSSIBLE CAUSE I REIVlEDY
Light pounding Loose connecting rod Replace bearings.
knock bearing.
Low oil supply. Add oil - check for
cause of low oil, Sect
3.5.
Oil badly diluted. Replace oil.
Pinging sound Carbon in cylinder. Remove carbon.
when engine is
suddenly or Spark too early. Adjust breaker points.
heavily loaded Retime spark if nec-
essary. Sect3.3.3
and 3.3.4.
Wrong spark plug. Install correct spark
plug Sect 3.3.5.
Valve hot. Adjust valve clearance.
Sect 3.7. L
...... ,
Fuel stale or low octane. Use good, fresh fuel.
Lean fuel mixture. Clean and adjust car-
buretor. Sect3.2.5.
Engine hot. Check air circulation.
Engine overheats Defective ventilating Check ventilators and
(See Sect 3.1.2) system. ducts.
Defective installation. Inspect complete instal-
lation including ducts
etc.
Improper lubrication. Check oil system.
Late ignition timing. Retime ignition.
Fuel mixture too lean. Adjust carburetor, Sect
3.2.5.
Generator overloaded. Inspect electrical load.

------
... ~ ........ -, 1Ioi.I: ,A;.r~ ........, - ...., ...... ~ '-'f .I.e .L',.I.'" """. ", ..... :~ • .c"1.o~\.. .L
TROUBLE-SHOOTING CHART 1, THE ENGINE (ConL)
TROUBLE
POSSIBLE GAUSE
REMEDY
. Low oil pressure
See Trouble-Shooting Chart
6
------
. _.
Spark plug fouled
Wrong spark plug gap.
Clean spark plugs and
in short periods of
set at O. 025"
time on gasoline
operation
-_ ..
... -
Speed fluctuations
See Trouble-8hooting Chart
Or incorrect speed 5 and Sect 3.4. '
-
TABLE OF DIMENSIONS AND CL}!;A1{A.Nt:J:!;.::;
All values in inches unless otherwise speCified.
EXHAUST VALVE SEATS (stellite)
Valve Seat Bore Diameter (standard) ........... .
1.361 ... 1
Seat Outside Diameter ........................ .
1. 364 - 1
Seat Width .................. , ....•............ 3/64 -1/
450
Seat Angle ..... ',' .......... ' ................. .
Available Oversizes .......................... .
.002 .005
.025
VALVE SPRINGS
Free Length ... " '.' ........................... . 1-7/8
Length,
Valve Closed ........... , ... ; ........ .
1. 528
Load,
Valve Closed .................... , ..... . 45 -49 lb
!-;'
Length,
Valve open ..................... , .... .
1.214
Load,
Valve Open ............................ . 83 -93 lb
10. WIRING D·IAGRAMS
The wiring diagrams on the following pages are typical and apply
standard MJ series generating plants. Wiring diagrams for spec,
models are available on request from the factory; send the plant:
and serial numbers with the request.
For revolving field plants, select the generator wiring diagram a
ing to the model, phase, and number of output wires. Select the'
, citer wiring diagram from the Magneciter model number on the p
nameplate.
For revolving armature plants, select the generator wiring diagr~
with the proper phase and' number of output wires-.---
Control wiring diagrams show the standard control circuit in sch
without the optional low aU pressure circuit. fli€lre are special c
trol diagrams with the optional low oil pressure circuit ,--'-
WIRING DIAGRAM LIST PAGE
~<.
3M.T A and 5MJB (Prior to Spec F Generator), , ... , . . . . . . . . . .. 132
4MJA Generator .. ' ... , ................ , .................. , 133
705MJB
and MJC Generator ...... , . . . . . . . . . . . . . . . . . . . . . . • . • 134
4MJA
Control (With Low Oil Pressure Circuit) ......... , .... , 135
3,MJA Control (No Low Oil Pressure Circuit) ...•......... ..• 136
3MJA
Control (With Low Oil Pressure Circuit ... " ......... , 137
5MJB
Control (No Low Oil Pressure Circuit) Begin SpeC' F. . . .. 138
5MJB
Control (No Low Oil Pressure Circuit) Prior to Spec F.. 13,9
5MJB Control (With Low Oil Pressure Circuit) Begin Spec F •. 140
705MJB
Control (No Low Oil Pressure Circuit) ............. , 141
705MJB
Control (With Low Oil Pressure Circuit) ............ 142
MJC
Control (No Low Oil Pressure Ci.rcuit) ....... . . . . . . . . .. 143
MJe Control (With Low Oil Pressure Circuit) .......... ,.... 144
04SX1NIA
Exciter ...•....... , ...... ~ . .. .. . . .. .. .. . . . . . . .• 145
04SX1N1B
and 06SXIN1B Exciter. . . . . . . . . .. . . . . . . . . . . . . . . .. 146
02SX1N1A
Exciter •... . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 147
4MJA
Control (No Low Oil Pressure Circuit ................ 148