Chevrolet 1948 light duty User manual

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OPERATOR'S MANUAL
FOR 1948
Chevrolet Light
and Heavy
Duty ·Trucks
INTRODUCTION
Whim y ou pur c hased your new
Chevrolet truck it was a bu siness
investment on your part. You can
rightl y expect it to pay divid e nds
on th e investment by handling
your hauling and transportation
requirements.
Ch ev rolet tru cks are d es igned
to handl e maximum loads effi-
ciently and economically, provid-
ing they are given the care and
consid e ration due any fine piece
of machin e ry subjected to severe
operating conditions.
This booklet has been prepared
to give you information pertaining
to the driving, care and mainte-
nanc e of your truck as well as to
provide technical data that may
be of v alue or interest to you.
The s ubject index at the right
is a ready reference to the key
subjects and will enable you to
find any subject covered in the
booklet .
Chevrolet Motor Division
General Motors Corporation
Detroit 2, Mi~l'an
SUBJECT INDEX
Driver 's Operatin(
Information
Page
Breaking-in Period. .......... 3
Controls and In struments 4
Pr estartin g Inspect i on ....... _ 13
Starting thelngine .. . .... . .. 14
GearsMbn g . 14
Cold Weather OperatIOn. 17
Hot Weather Operation ... .,.. . 18
Tire Inflation. .. . ........ 19
T ool s ...... 20
Description, Care and
Maintenance
Preventive M ai ntenance ...
Engine . ..
Cooling System
Clutch ..
Transmission . .. .
· 11
· 11
.. 34
. 40
41
Rear Axle . .. .
hont Axle .. .
Steering Ge ar
Brake Sy stem..
43
. .... ' 45
.. . 47
S prings and Sha ckl es ..
Electrical System ...
Tires ..
Lubrication
· 48
51
51
58
Eng in e.. . 62
Rear Axle and Transmiss i on .. . 70
Universal Joints .. ..' 71
Front Wheel Bearings .. 73
Re ar Wheel Bearings .. . 73
Chassi s.. . 74
Hints for Lot:ating
Road Troubles
Engine ...
Ughts ..
General. .....
General Information
81
. 85
.. 86
Manufacturer 's Warranty ...' .. 87
Tire Warranty .. . ... . 88
Owner's Se rv ice Po licy.. .. 88
Service Fa c il i ties .. . ... . 88
Labor Charges and Repa ir Pa r ts 89
Technica1 Data
Unit Capac i ly Chart .. ... ... !Il
lamp Bulb Chart ... ... !Il
Specificat io ns ... . 90
Adjustment Specifications .... 92
load Capacily Chart. ......... 93

1ig. J -Controls and 'nstrumenfs- '12 and 'I. Ton

CHAPTER I
DRIVER'S OPERATING INFORMATION
BREAKING-IN PERIOD
The moving parts of your Chevrolet truck are preCISlon
built to very close fits. For this reason high speeds should be
avoided and special attention given to proper lubrication for
the first 2,000 miles.
To properly break in the moving parts and assure long care-
free service do not drive faster than:
35 miles per hour for the first 100 miles
45 miles per hour for the next 200 miles
50 miles per hour for the next 200 miles
Continuous high speed driving should be avoided until the
truck has been driven 2,000 miles. The engine should not be
raced or run at high speed in lower gears, especially until it
is thoroughly warmed up.
Fig. 2-Conlrols and Instrumenls-I-I '12 and 2 Ton
• 3 •

CONTROLS AND INSTRUMENTS
The type, location and operation of instruments and con-
trols vary on different models and makes of vehicles; therefore,
regardless of the experience an owner or driver may have had
it ·is advisable to familiarize one's -self with the instruments
and controls, and their use before driving this new truck. The
locations of the various instruments and controls are shown in
figures 1 and 2.
Instrument Group
Gasoline Gauge. The electrically operated gasoline gauge is at
the upper left side of the instrument group (fig. 3). It is wired
through the ignition switch; therefore, only indicates the
Fig. 3-lnstrument Group
amount of fuel in the tank when the
ignition switch is turned on.
Temperature Indicator. The water
temperature indicator is at the
lower left side of the instrument
group (fig. 3). It is, in effect, a ther-
mometer with the operating bulb
located in the water jacket at the
left rear corner of the cylinder
head. Normally this thermometer
will register between 140 and 180
degrees when the engine is thoroughly warmed up. The driver
should watch this instrument closely, as a quick rise in tem-
perature usually indicates trouble. Should the temperature
rise above 200 degrees the engine should be stopped and a
check made for cause of overheating (see "Hints for Locating
Road Troubles," page 85).
NOTE: Do not remove the radiator ~ap when engine is exces-
sively hot, do not put water in a hot engine and do not run en-
gine when indicator is above 212 degrees.
Ammeter (Battery Indicator). The ammeter is the right upper
instrument in the group (fig. 3). The ammeter indicates the
flow of current to and from the battery, except the current
taken by the starting motor. When the engine is turned off
or idling and any of the electrical equipment is in use, it is
• 4 •

natural for the ammeter to show discharge. When the engine
is running at medium speed and most of the electrical equip-
ment is turned off the ammeter should show a slight charge,
depending on the state of charge of the battery. Should the
ammeter show discharge when the truck is being driven at
medium speed, trouble is indicated in the charging system
and the battery will soon become discharged.
Oil Pressure Gauge. This instrument is in the lower right side
of the instrument group (fig. 3). The oil pressure gauge indi-
cates whether or not the oil pump is working, but does not
indicate the amount of oil in the crankcase.
The pressure gauge reading is controlled by the engine
speed and the oil being used. A low reading is normal at idling
speeds with a warm engine and light oil; however, as the
engine speed is increased the hand should move over near the
"15" mark. In cold weather (especially with heavy oil) the
hand may move over to the "30" mark at comparatively low
engine speeds. This indicates that the
oil is too heavY to properly lubricate
the engine.
NOTE: Do not accelerate the engine
excessively until the oil is suffi-
ciently warm to permit a lower pres-
sur~. If the gauge does not show
any pressure, stop the engine im-
mediately and determine the cause.
Speedometer. The speedometer is
located to the right of the instru-
ment group (fig. 4). As the vehicle
Fig. 4-Speeclomefe,
is driven, the hand moves around the dial indicating the speed
of the vehicle in miles-per-hour. The figures visible through
the opening near the center of the speedometer indicate the
total mileage the truck has been driven. This part of the
speedometer is known as the odometer.
Fig. 5-lgnifion$wltch
Switches
Ignition Switch. The ignition switch,
located near the bottom of the in-
strument panel to the right of the
steering column (fig. 5), is used to
• 5 •

"make" and "break" the ignition circuit when starting or stop.-
ping the engine. There are two "off" positions, one to the right
and one to the left of the "on" (vertical) position. The key can
be removed with the ignition switch in any of the three posi-
tions.
When the ignition is turned off by turning the switch
clockwise and the key removed the ignition can . be turned
"on" or "off" without the use of a key. When the ignition is
turned off by turning the switch counterclockwise and remov-
ing the key the ignition is locked "off".
Fig. 6-1ighting Switch
Lighting Switch. The Lighting
switch, located to the left of the in-
strument group (fig. 6) controls the
instrument lamps, headlamps, park-
ing lamps and tail lamp. When this
switch is pulled out to the first "on"
position the parking lamps and tail
lamp are lighted. When the switch
is pulled out to the last position the
headlamps and tail lamp are lighted.
Current for the lighting circuits
passes through a thermal circuit breaker located on the light-
ing switch behind the instrument panel. In case all lights fail
to operate check for trouble at the thermal circuit breaker.
The instrument lights can be dimmed or turned off by turning
the light switch button clockwise.
Dimmer Switch. The dimmer switch located on the toe-board
to the left of clutch pedal (fig. 10) is used to switch the head-
lamp beam from "high" to "low" or "low" to "high". Each
time the switch is depressed the light beam is reversed. A
headlamp beam indicator is located between the 0 and 80 at
the bottom of speedometer. When the lights are on upper beam
a red light is visible through the in-
dicator opening. Avoid use of upper
beam when meeting other vehicles
on the highway or in city traffic.
Dome Lamp Switch. The dome lamp
switch is located at the left end of
the dome lamp assembly directly
above the rear window (fig. 7).
Moving this switch backward turns
• 6 •
Fig. 7-Dome Light and
Switch

the light on and moving it forward
turns the light off.
Horn Button. The horn button is
conveniently located at the center of
the steering wheel. Depressing the
button blows the horn.
Controls
Hand Throttle Control. The throttle
control knob is located on the in-
strument panel directly above the
ignition switch (fig. 8). Pulling out
on the control knob opens the car_
fig, 8-Throtfle and Choke
Controls
buretor to provide a uniform engine speed above the idle set..:.
ting. It is generally advisable to pull the hand throttle control
out slightly when starting the engine, especially if the engine
has a tendency to stall a time or two after starting.
Choke Control. The carburetor choke control knob is located
directly above the hand throttle control knob (fig. 8). The
purpose of this control is to close (or partly close) the carbu-
retor choke valve restricting the air intake and producing a
richer fuel mixture for starting.
When the engine is warm and the weather is warm, it
should not be necessary to use the choke when starting the
engine. When it is necessary to use the choke for starting, it
should be pushed part way in as soon as the engine starts and
all the way in as soon as the engine will run smoothly without
its use.
CAUTION: Excessive use of the choke will provide a fuel mix-
ture too rich to burn. Some of this unburned fuel will leak past
Fig. 9-Starter and Accelerafor
Pedals
the pistons and dilute the engine
oil and result in improper lubrica-
tion, excessive engine wear and
poor performance.
Starter Pedal. The starter pedal is
located near the center of the toe
board to the right of the accelerator
pedal (fig. 9). Depressing this pedal
with the foot engages the starting
motor pinion with the teeth in 'the
• 1 •

engine flywheel and closes the starter switch to provide an
electrical circuit between the battery and starting motor, there-
by cranking the engine. The starting motor draws considerable
current from the battery; therefore, it should not be operated
for more than 15 seconds at a time. If the engine does not start,
locate the cause and correct it before the battery is run down.
CAUTION: The starter pedal must be released as soon as the
engine starts and should never be depressed when the engine is
running or serious damage may result.
Accelerator Pedal. The accelerator pedal, located to the left
of the starter pedal (fig. 9), is used to open and close the
Fig. J o-ell/reh and Brake Pedals
carburetor throttle valve.
The driver rests his right foot
on this pedal and by varying
the pressure applied opens
the carburetor throttle the
correct amount to obtain the
desired engine or vehicle
speed.
Clutch Pedal. Is conveniently
located for use by the driv-
er's left foot (fig. 10). It is
used to engage and disengage
the clutch, thereby connect-
ing the engine to or disconnecting it from the transmission and
drive
line to rear wheels.
The clutch pedal should have % to 1 inch free travel; if less
than %" adjust free travel (see Clutch Adjustment, page 41).
NOTE: Never drive with the foot resting on the clutch pedal as
this produces undue wear on the throwout bearing and other
parts.
Brake Pedal. Located to the right of clutch pedal (fig. 10).
Depressing this pedal applies the hydraulic service brakes at
all four wheels in proportion to the pressure applied on. the
pedal.
Hand Brake Lever-I-I¥. and 2 Ton. Extends up through floor
to the right of the gear shift lever with the grip just below
the instrument panel (fig. 2). Pulling this !ever back applies
the rear wheel brakes by means of mechanical linkage entirely
independent of the hydraulic system. To release brakes, grip
• 8 •