GMC 71 Series User manual

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There are no warranties, expressed or implied, made by Seller on GM Diesel engine units,
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engines, products, or 'Parts' furnisHed hel'e:unde~except r as provided ~\ the manufacturer's
standard warranty as follows:
. "Manufacturer y.rarrantsnev.:.GM Diesel products (~C1udingoricpnalequipment placed thereon
by the manufacture:.::,e?,cepjbatterie_s) :'0 b~ free from defects in, ~aterial or workmanship und~r
normal use and service. 'The Manufacturer's obligation under this warranty is llinited to mak-
ing good at its factory any part or parts of such products which shall be returned to it with
transportation charges prepaid within six (6)months from date of delivery of said products
to the original purchaser, and which its examination shall disclose to its satisfaction to have
been thus defective. This warranty is in lieu of all other warranties, expressed or implied, and
all other obligations and liabilities on its part, and it neither assumes n~r authorizes any
person to assume for it any Othe~liability in connection with its products."
This warranty shall not apply to any prodUft which shall have been repaired or altered out-
side' of 'an\authorized Detroit Diesel Engine'Division Service Stduon in any way so as in the
[udqment of the 'Manu{a~turerto affect its st;roility a~d ~~liabilitynor which has been sublect
to misuse, negligence or accident.
The Manufc;xcturerreserves the right to make changes in design or add any improvements
on its products dt any time without incurring any obligations to install same on units previously
delivered by it.
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----

GENERAL MOTORS
DIESEL
SERIES 71
OPERATOR'S
MANUAL
for
THREE, FOUR, AND SIX CYLINDER
INDUSTRIAL UNITS
PRODUCT SERVICE SECTION
DETROIT DIESEL ENGINE DIVISION
GENERAL MOTORS CORPORATION
DETROIT 28, MICHIGAN
FORM 6SE-60
UTHO IN U. S. A. REPRINUO 6·54

FOREWORD
This manual contains instructions on the operation and pre-
ventive maintenance of the current General Motors Series
71 Diesel Engines in the 3, 4, and 6 cylinder single and
multiple engine industrial models. It is not intended to cover
engine repair or overhaul, as such work should be per-
formed by an authorized Detroit Diesel Engine Division
Dealer or Distributor.
Sufficient descriptive material, together with numerous illus-
trations, is included to enable the operator to understand
the basic construction of the Series 71 engine and the prin-
ciples by which it functions.
o
The operator should familiarize himself thoroughly with
the contents of this manual before operating the engine or
carrying out adjustment or maintenance procedures.

TABLE OF CONTENTS
SUBJECT SECTION
Principles of Operation.
Engine Standardization.
Accessory Arrangement.
Engine Models.
General Specifications.
Unit, Model, Option and Accessory Designation.
GENERAL INFORMATION
DESCRIPTION OF ENGINE SYSTEMS AND CONTROLS-
lubricating, Cooling, Air, and Fuel Systems.
Emergency Engine Shut-down, Automatic Engine Shut-down.
Governors.
Electrical System.
Cold Weather Starting.
POWER TRANSMISSIONS-
Power Take-Off with Short Shaft or Outboard Bearing, and with Double
Plate Clutch.
Single Engine Reduction Gear.
Twin Engine Transfer Gear.
Clutch for Multiple Engine Units.
Quad Engine Reduction Gear.
OPERATION AND MAINTENANCE-
Operating Instructions.
lubrication and Preventive Maintenance.
lubricating Oil and Fuel Oil Specifications.
Engine Tune-up.
Throttle Adjustments for load Equalization on Twin and Quad Engine Units.
TROUBLE SHOOTING, ENGINE STORAGE, ENGINE INSTALLATION-
locating a Misfiring Cylinder, Checking Compression Pressure.
Trouble Shooting Charts.
Checking Electrical System.
Storage Chart.
Engine Installation.

PAGE4
GENERAL MOTORS DIESEL
SEC.
PRINCIPLES OF OPERATION
The Diesel Principle-The Diesel engine is an in-
ternal combustion power unit, in which the heat
of fuel is converted into work in the cylinder of the
engine.
In the Diesel engine, air alone is compressed in
the cylinder; then, after the air has been com-
pressed, a charge of fuel is sprayed into the cyl-
inder and ignition is accomplished by the heat of
compression.
The Two-Cycle Principle-In the two-cycle engine,
intake and exhaust
take place during
part of the compres-
sion and power
strokes, respectively,
as shown in Figures
1, 2, 3 and 4. In con-
trast, a four-cycleen-
gine requires four
piston strokes to com-
plete an operating
cycle;thusduringone
half of its operation,
the four-cycleengine
functions merely as
an air pump.
Fig. J -Scavenging.
A blower,which is mounted on the side ofthe engine,
forcesair intothe cylinders toexpel the exhaust gases
and to supply the
cylinders with an
abundance of fresh
air for combustion.
Fig. 2-Compression.
A series of ports cut
into the cylinder
wall, which are
above the piston
when it is at the bot-
tom of its stroke, ad-
mit the air from the
blower into the cylin-
der as soon as the
top face of the piston
uncovers the ports,
u
as shown in Fig. 1. The unidirectional flow of air to-
ward the exhaust valves produces a scavenging
effect, leaving the cylinders full of clean air when
the piston again covers the inlet ports.
As the piston continues on the upward stroke, the
exhaust valves close and the charge of fresh air is
subjected to the final compression,as shown in Fig. 2.
Shortly before the piston reaches its highest posi-
tion, the required amount of fuel is sprayed into the
combustion space by the unit fuel injector, as
shown in Fig. 3. The
intense heat gener-
ated during the high
compression of the
air ignites the fine
fuel spray immedi-
ately, and the com-
bustion continues as
long as the fuelspray
lasts. The resulting
pressure forces the
piston downward on
its power stroke until
the exhaust valves
are again opened.
As shown in Fig. 4, Fig. 3-Power.
the burnt gases es-
cape into the exhaust manifold as the downward
moving piston is about to uncover the inlet ports.
When these ports are
uncovered, the cylin-
der is again swept
with clean scaveng-
ing air, as shown in
Fig. 1. This entire
combustion cycle is
completed in each
cylinder for each
revolution of the
crankshaft, or, in
other words, two
strokes; hence the
"two-stroke cycle".
Fig. 4-Exhaust.

GENERAL MOTORS DIESEL
ENGINE MODELS PAGE 5
SEC. 1
ENGINE STANDARDIZATION
The two-cycle Diesel engines. discussed in this text
are offered in three, four, and six cylinder models
having the same bore and stroke and using the
same parts wherever possible. Thus, the major work-
ing parts, such as injectors, pistons, connecting rods,
bearings, and other parts are interchangeable.
ACCESSORY ARRANGEMENT
The blower, water pump, governor, and fuel pump
form a group of standard accessories which can be
located on either the right or the left side of the en-
gine, regardless of the direction of rotation. Further
flexibilityin meeting installation requirements is ob-
tained by placing the exhaust manifold and the
water outlet manifold on either side of the engine.
This variation in the arrangement of parts is secured
by having both the cylinder block and cylinder head
symmetrical at both ends and with respect to each
other. These various arrangements are designated
by the letters A, B, C, or D in the model number.
Letters R or L in the model number designate the
directionofrotation.
Engine Type
On the LeftSide On the RightSide
A
Allstandard accessories Exhaust outlet
Water outlet
Allstandard accessories
B
Exhaust outlet
Water outlet
C
Exhaust outlet All standard accessories
Water outlet All standard accessories
DExhaust outlet
Water outlet
fig. 5-Accessory and Manifold Arrangements (Engine Viewed from the Rear).
ENGINE MODELS
Flexibilityin the location of the basic engine acces-
sories (such as the blower, governor, water outlet
manifold and exhaust manifold),and a wide range
of power take-offs and reduction gears makes it
possible to provide a suitable unit to fulfill most
requirements.
In the followingtabulations of some ofthe more com-
mon single-engine industrial models is shown the
interrelation of the model numbers of the three, four,
and six cylinder engine units. For each model
group, the direction of rotation, the accessory ar-
rangements, and the power take-off is indicated.
However, to meet specific requirements, either right-
or left-rotatingengines can be furnished.
In addition to single engine industrial models, the
General Motors Series 71 "Twin" and "Quad" mul-
tiple engine power units are designed to deliver in-
creased power to a single drive shaft with important

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GENERAL MOTORS DIESEL
GENERAL SPECIFICATIONS PAGE 7
SEC. 1
Fig. 9-Typical Quad Engine Unit.
GENERAL SPECIFICATIONS
3-71 ~71 6-71
346
4~ in. 4~ in. 4~ in.
5 in. 5 in. 5 in.
.16 to 1 16 to 1 16 to 1
213 284 425
1-3-2 1-3-4-2 1-5-3-6-2-4
1-2~3 1-2-4-3 1-4-2-6-3-5
4 5 7
Number of Cylinders ................•.............
Bore : .
Stroke .
Compression Ratio (Nominal) .
Total Displacement - Cubic Inches .
Firing Order - R.H. Rotation .
Firing Order - L.H. Rotation ..
Number of Main Bearings .

GENERAL MOTORS DIESEL
PAGE 8 TYPICAL UNIT ILLUSTRATIONS
SEC. 1
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GENERAL MOTORS DIESEL
TYPICAL UNIT ILLUSTRATIONS PAGE 9
SEC. 1
fig. J J -End Cross Section of a Typical Industrial Unit.

GENERAL MOTORS DIESEL
PAGE 10
SEC. 1
TYPICAL GENERAL MOTORS THREE, FOUR AND SIX-CYLINDER SERIES 71 POWER UNITS
o
MODELS 3028C, 4028C, 6028C
Model 6028C Shown
fig. J2
MODELS 3029C, 4029C, 6029C
Model 6029C Shown
o
fig. J3
MODELS 3030C, 4030C, 6030C
Model 4030C Shown
,fig. J4 o

GENERAL MOTORS DIESEL
TYPICAL UNIT ILLUSTRATIONS PAGE 11
MODELS 3055C, 4055C, 6055C
Model 3055C Shown
o
Fig. 16
MODELS 3061A, 4061A, 6061A
Model 6061 A Shown
SEC. 1
Fig. 15
MODELS 3057C,' 4057C, 6057C
Model 4057C Shown
Fig. 17

GENERAL MOTORS DIESEL
PAGE 12 TYPICAL UNIT ILLUSTRATIONS
SEC. 1
MODELS 12103, 12104
Fig. J 8
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GENERAL MOTORS DIESEL
TYPICAL UNIT ILLUSTRATIONS PAGE 13
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PAGE 14
GENERAL MOTORS DIESEL
SEC. 1
MODEL, SERIALAND UNIT DESIGNATIONS
Fig. 20-Typical Unit Number and Model As Stamped
on Cylinder Block of Single Engine Units.
The unit number, and model, are stamped on every
single engined unit at the upper right hand comer
of the cylinder block, blower side (Fig.20). On mul-
tiple engine units, a model number is stamped
below the unit number (Fig. 21).
The unit number stamped on the block of each
engine is the same as that stamped on the Option
and Accessories Plate, which is attached to the
rocker cover of each single engine unit (Fig. 22).In
the case of a multiple-engine unit, it is attached to
the rocker cover of only one of the engines.
The unit number stamped on the cylinder block
and on the Option and Accessories Plate desig-
': .nctes the number of cylinders (3),engine series (A
for the 71 series) and the numerical serial number
(such as 18959).
On single engines the suffix (Re) as shown in Fig.
20, designates the rotation and accessory arrange-
ment of that particular engine.
On multiple engines the model number stamped
on the cylinder block of each engine is the "basic
engine model number" and differs from the model
number stamped on the plate. The basic engine
Fig. 21-Typical Unit and Model Number As Stamped
on Cylinder Blocks of Multiple Engine Units
model number (671LA61)denotes the number of
cylinders (6),engine series (71),rotation of the en-
gine (L), location of the standard accessories (A),
and application (61).The model number stamped
on the plate indicates the number of cylinders in
the entire unit and the model type.
In addition to the unit number and the model
number, the Option and Accessories Plate lists the
rated H.P.,continuous H.P.,maximum RPMno load,
and all Options and Accessories included in the
unit.
The option and accessories equipment installed
on the unit are listed on the plate in alphabetical
sequence with its type number. This enables the
customer to order correctly any option or accessory
listed on the plate. All groups of parts used on a
unit are standard unless otherwise listed on this
plate.
Power take-off assemblies, reduction gears, etc.,
may also carry name plates pertaining to that par-
ticular assembly.
The operator should include all data given on the
Option and Accessory Plate with any order for parts.
Fig.22-0ption and Accessories Plate.
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GENERAL MOTORS DIESEL
LUBRICATING SYSTEM PAGE 1
SEC. 2
OIL, WATER, AIR, AND FUEL SYSTEMS
Engine operation is the result of the functioning of
four separate and distinct systems within the engine
and its standard equipment. Each of these systems
directs the flow of either air, water, lubricating oil or
fuel to the various points where it is needed.
This section contains a brief description and opera-
tional outline of each of the four systems and its
functional mechanisms.
LUBRICATING SYSTEM
Description-Figure 1 illustrates the schematic ar-
rangement of the various units and controlvalves of
the lubricating oil circulating system. This system
consists of an oil pump, oil cooler, and oil filter,to-
TO VALVE OPERATING MECHANISM,
CAMSHAFT AND BLOWER
OIL COOLER OIL FILTER
OIL COOLER
BY-PASS
VALVE
OIL PUMP INTAKE SCREEN
Fig. I-Schematic Diagram of Typical Lubricating System.

GENERAL MOTORS DIESEL
PAGE 2 LUBRICATING SYSTEM
SEC. 2
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GENERAL MOTORS DIESEL
PAGE 4 LUBRICATING SYSTEM
SEC. 2
DRAIN TO OIL PAN
Fig. 4-Lubrication Diagram-Blower.
gether with a suitable reliefvalve in the pump, a by-
pass valve at the oil cooler and a pressure regulator
valve in the cylinder block oil gallery which insures
positive lubrication at all times.
Oil for lubrication of the connecting rod bearings,
piston pins, and for cooling the piston head, is pro-
vided through the drilled crankshaft from the adja-
cent forward.main bearings. The gear train is lubri-
cated by the overflowof oilfromthe camshaft pocket
through a communicating passage into the flywheel
housing. A certain amount of oil spills into the fly-
wheel housing from the camshaft, balancer shaft,
and idler gear bearings. The blower drive gear bear-
ing is lubricated through an external pipe from the
rear horizontal oil passage of the cylinder block.
Oil overflows through two holes, one at each end of
the blower housinq, as shown in Fig. 4, providing
lubrication for the blower drive gears at rear end
and governor mechanism at the frontend.