Chevrolet 10 Series 1968 User manual

ST 133-SB

-------------------------------------------------- - --------- - — — -------- - ------ — ------------ -V SECTION INDEX
1968 SECTION NAME
0GENERAL INFORMATION
AND LUBRICATION
SERIES 10 through 60 1A HEATER AND
AIR CONDITIONING
I B BODY
CHEVROLET TRUCK
CN
FRAME
CHASSIS 3FRONT SUSPENSION
4-WHEEL DRIVE
SERVICE MANUAL 4REAR SUSPENSION
AND DRIVELINE
FOREWORD
This manual includes procedures for maintenance and
5BRAKES
6ENGINE
adjustments, minor service operations, removal and in
stallation for components of Chevrolet Series 10 throu h
60 Trucks. Procedures involvin disassembly and assem
bly of major components for these vehicles are contained
in the 1968 Truck Chassis Overhaul Manual.
The Section Index on this pa e enables the user to
quickly locate any desired section. At the be innin of
each section containin more than one major subject is a
6K ENGINE COOLING
6M FUEL SYSTEM
6T AIR INJECTION
REACTOR SYSTEM
Table of Contents, which ives the pa e number on which
each major subject be ins. An Index is placed at the be
innin of each major subject within the section. 6Y ENGINE ELECTRICAL
Summaries of Special Tools, when required, are found
at the end of major sections while specifications coverin
vehicle components are presented at the rear of the
manual.
This manual should be kept in a handy place for ready
reference. If properly used, it will enable the technician
to better serve the owners of Chevrolet built vehicles.
All information, illustrations and specifications con
7CLUTCH AND TRANSMISSION
OO
FUEL TANK AND
EXHAUST SYSTEM
9STEERING
tained in this literature are based on the latest product
information available at the time of publication approval.
The ri ht is reserved to make chan es at any time without
notice. 10 WHEELS AND TIRES
11 CHASSIS SHEET METAL
12 ELECTRICAL—BODY
AND CHASSIS
• • • 13 RADIATOR AND GRILLE
CHEVROLET MOTOR DIVISION
Ge eral Motors Corporatio
DETROIT, MICHIGAN 14 BUMPERS
15 ACCESSORIES
SPECIFICATIONS
© 1967 Pri ted i U.S.A.
Ge eral Motors Corporatio

w
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SECTION 0
GENERAL INFORMATION
AND LUBRICATION
INDEX
Pa e
Model Line Up . ......................................................................... 0-1
Truck Model Identification ................................................... 0-1
Unit and Serial Number Loca tions.......................................0-1
GVW Serial Number P la te .......................................................0-2
En ine N um ber..........................................................................0-2
Service Parts Identification Plate .......................................0-3
Keys and Locks .......................................................................0-3
Pa e
Pushin , Towin , and L ift in ................................................0-3
Towin .......................................................................................0-3
Push Starts - Trucks Equipped with Automatic
Transmission................................................... 0-4
Liftin Chevy Van with H o is t................................................ 0-4
Liftin with Auto Ja ck .............................................................0-4
Load Capacity C h art................................................................0-4
GENERAL INFORMATION
MODEL LINE UP
The 1968 Truck model line up consists of 441 models
on 39 wheelbases. The 104-inch wheelbase formerly
offered in 3/4- and 1-Ton Forward Control Chassis
applications has been deleted and the new 116-inch
wheelbase application has been added.
Seventy-three models are deleted for 1968. These
deleted units comprise of all Windshield Cowls, formerly
offered in Series 10 throu h 60; all Round-Front Step-
Vans, Square-Front Step-Vans, and Forward Control
Chassis with I-beam front suspension, formerly offered
in Series 20 and 30; all Tilt-Cabs with the Detroit
Diesel 3-53N en ine, formerly offered in Series TT40;
and all Tilt-Cabs with the Truck D478 en ine, formerly
offered in Series TG60.
Twenty-seven models are new to the line-up. These are
Forward Control units in Series 20 and 30 featurin new
chassis with independent front suspension. The new panel
and new suburban trucks introduced as 1967 interim
vehicles are not included as new in the 1968 line-up.
With the introduction of the new Series 20 and 30
Forward Control models, the Round-Front Step-Van con
fi uration is discontinued. Square-Front Step-Vans all
have new bodies; the 125-inch wheelbase is retained and
the 137-inch wheelbase is replaced with a new wheelbase
of 133 inches. Forward Control Chassis also are con
tinued. In these applications, the 104-inch wheelbase is
deleted; the 125-inch wheelbase is retained; the 137-inch
wheelbase is replaced with a new wheelbase of 133
inches; and a new 157-inch wheelbase is introduced for
the accommodation of 14-foot bodies.
TRUCK MODEL IDENTIFICATION
A lettered prefix and 5-di it basic series num
berin system does not chan e for 1968 Truck model
identification.
A combination GVW and serial number plate is used
on all models (fi . 1) except Tilt Cab and is located on
the left door hin e pillar on Conventional and L.D.F.C.
models, on the upper left hand side of dash panel on cowl
models, and on the steerin column on Forward Control
models. On Tilt cab models (fi . 2) the serial number
and GVW plates are located on the left door hin e pillar.
UNIT AND SERIAL NUMBER LOCATIONS
For the convenience of service technicians and en i
neers when writin up certain business papers such as
L.&M.R.’s, Product Information Reports, or reportin
product failures in any way, the location of the various
unit numbers have been indicated. These unit numbers
and their prefix or suffix are necessary on these papers
for various reasons - such as accountin , follow-up on
production, etc.
CHEVROLET
MAXIMUM GVW RATING
^ VEHICLE IDENTIFICATION NUMBER ^
1 CS 107048P1000 5 1
DDI I
Fig. 1—GVW a d Serial Number Plate Fig. 2—Vehicle Ide tificatio Plate a d GVW Plate Tilt Cab
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-
The prefixes on certain units identify the plant in
which the unit was manufactured, and thereby permits
proper follow-up of the plant involved to et corrections
made when necessary.
Always include the prefix in the number.
GVW AND SERIAL NUMBER PLATE
The combination GVW and serial number plate reveals
the truck GVW ratin and serial number. Also included
on the plate is a space for indicatin the date the truck
was delivered to the customer.
A typical serial number is explained in the followin
chart.
(a) See the followin Series and Model Identification
Chart.
(b) Last number of model year 1968.
(c) P--GM Truck.
(d) Unit numberin will start at 100,001 at all plants.
ENGINE NUMBER
The en ine number indicates manufacturin plant,
month and day of manufacture, and transmission type. A
typical en ine number would be F1210FA, which would
breakdown thus:
F - Manufacturin Plant (F-Flint, T-Tonawanda)
12 - Month of manufacture (December)
10 - Day of manufacture (tenth)
FA - Transmission and en ine type
Vehicle No. GS107048P100025 is Broken Down
Series and Model Assembly Unit
Model No. Year Plant Number
(a) (b) (c) (d)
GS10704 8 P 100025
SERIES AND MODEL IDENTIFICATION
CHASSIS 1 ENGINE 2
0 - Conventional (Conventional Cab, Panel, Suburban) A - All
G - Li ht-Duty Forward Control D - L-4 Diesel
H - Conventional (Short Conventional Cab) E - V-8 Gasoline
J - Tandem (Short Conventional Cab) G - V-6 Diesel (GMC Truck)
k - Four-Wheel Drive J - V-8 Diesel
M - Tandem (Conventional Cab) M - V-6 Gasoline
P - Forward Control m -L-6 Gasoline
S - School Bus T - L-3 Diesel
T - Conventional (Tilt-Cab) V - V-6 Diesel (Detroit Diesel)
W - Tandem (Tilt-Cab)
EXAMPLE: 1 2 3 4 5 6 7
C S 1 0 7 0 4
BODY AND BRAKE* 6-7
GVW RANGE 3 CAB-TO-AXLE DIMENSION 4-5 (* - Hydraulic unless otherwise specified.)
0 - All 00 - All 18 - 108-113" 00 - All
0 - 3600-5600# [07] - 42-47" 19 - 114-119" 02 - Flat Face Cowl
2 - 5500-8100# 09 - 54-59" 20 - 120-125" 03 - Cab
3 - 6700-10000# 10 - 60-65" 21 - 126-131" Is! - Stepside Pickup
4 - 10000-20000# 12 - 72-77" 22 - 132-137" 05 - Panel
5 - 15000-23000# (sin le axle) 13 - 78-83" 23 - 138-143" 06 - Suburban (Panel Rear Doors)
24000-30000# (tandem axle) 14 - 84-89" 25 - 150-155" 09 - Cab, Platform, and Stake Rack
6 - 15000-26000" (sin le axle) 15 - 90-95" 28 - 168-173" 13 - Cab (full air brakes)
30000-45000# (tandem axle) 16 - 96-101" 31 - 186-191" 16 - Suburban (Tail and Lift ate)
7 - 18500-27000# (sin le axle) 17 - 102-107" 26 - Custom Suburban (Panel Rear Doors)
36000-45000# (tandem axle) 34 - Fleetside Pickup
8 - 25500-32000# (sin le axle) 35 - Forward Control Panel (Square-Front)
36000-48000# (tandem axle) 36 - Deluxe Suburban (Panel Rear Doors)
42 - Forward Control Chassis
62 - Flat Face Cowl (full air brakes)
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-3
MAJOR COMPONENTS IDENTIFICATION AND
SERIAL NUMBER LOCATIONS
Axles
• Rear Axle Serial Number Located at the Bottom
Flan e of Carrier Housin .
• Rear Axle (Except Half Ton) Forward Upper Surface
of Carrier.
• 2-Speed Axle Serial Number on Face of Carrier.
• Tandem Axle, Forward Unit—Unit and Assembly
Numbers Stamped on Left Side of Carrier.
• Tandem Axle, Rear Unit—Unit and Assembly Num
bers Stamped on Upper Portion of Carrier.
Transmissions
• 3-Speed Transmission Unit Number Located on
Lower Left Side of Case Adjacent to Rear of Cover.
• 4-Speed Transmission Unit Number Stamped on Rear
of Case, Above Output.
• New Process 5-Speed Unit Number Stamped on Rear
Face of Case to Left of Drain Plu , Spicer 3000
Series. Above Plu , Spicer 5000 Series on Nameplate
Left Side of Case at Rear.
• 5-Speed Clark Transmission Unit Number Stamped
on Left Rear of Case, Near P.T.O. Plate.
• 4-Speed Auxiliary Transmission Unit Number.
• Allison Transmission Part Number and Production
Date on Ta Left Side of Case.
• Power lide Transmission Unit Number Located on
Ri ht Rear Vertical Surface of Oil Pan.
• The Turbo Hydra-Matic Transmission Serial Number
is Located on the Li ht Blue Plate on the Ri ht Side
of the Transmission.
Engines
• 6-Cylinder En ine Unit Number Located on Pad at
Ri ht Hand Side of Cylinder Block at Rear of
Distributor.
• 8-Cylinder En ine Unit Number Located on Pad at
Front, Ri ht Hand Side of Cylinder Block.
• Diesel En ine (Four Cycle) Serial Number.
• Diesel En ine Serial Number 6-Cylinder Forward of
Ri ht Cylinder Head, 3, 4-Cylinder Rear Ri ht of
Cylinder Head.
Delcotrons
• Delcotron Unit Serial Number—Top of Rear Housin .
Batteries
• Battery Code Number Located on Cell Cover Top of
Battery.
Starters
• Starter Serial Number and Production Date Stamped
on Outer Case, Toward Rear.
SERVICE PARTS IDENTIFICATION PLATE
The Chevrolet Truck Service Parts Identification Plate
(fi . 3) is provided on all Truck models. On most series
it will be located on the inside of the love box door, on
P&G series it will be located on an inner body panel.
IMPORTANT: RETAIN THIS PLATE AS A PERMANENT RECORD
Fig. 3—Service Parts Ide tificatio Plate
The plate lists the vehicle serial number, paint informa
tion and all Production options or Special Equipment on
the vehicle when it was shipped from the factory.
ALWAYS REFER TO THIS INFORMATION WHEN OR
DERING PARTS.
KEYS AND LOCKS
Two keys (hexa onal head) are provided with each ve
hicle. The keys operate the i nition switch and door
locks.
PUSHING, TOWING, AND LIFTING
NOTE: Towin to start is not recommended
due to the possibility of the disabled truck ac
celeratin into the two vehicle.
When a push start is necessary turn off all electrical
loads such as heater, radio and, if possible, li hts, turn
on key, depress the clutch, and place the shift lever in
3rd ear. Release the clutch when your speed reaches
10 to 15 miles per hour.
TOWING
All Except Four Wheel Drive Trucks
Normally your vehicle may be towed with all four
wheels on the round for distances up to 50 miles at
speeds of less than 35 MPH. The en ine should be off
and the transmission in neutral.
However, the drive wheels (rear wheels, front wheels)
must be raised off the round or the drive shaft discon
nected when the transmission is not operatin properly
or when a speed of 35 MPH or distance of 50 miles will
be exceeded.
CAUTION: If car is towed on its front wheels
only, the steerin wheel must be secured with
the wheels in a strai ht ahead position.
Four Wheel Drive Trucks
It is recommended that the- truck be towed with the
front wheels off the round. The truck can be towed,
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-4
Fig. 4—Vehicle Lifti g Poi ts - Chevy Va
however, with the rear wheels off the round if there is
dama e in the rear wheel area. In this event, the trans
mission selector lever should be placed in the “ N”
(neutral) position and the front drive disen a ed. Towin
speeds should not exceed 35 MPH for distances up to
50 miles. If truck is towed on its front wheels, the
steerin wheel should be secured to keep the front wheels
in a strai ht-ahead position.
When towin the vehicle at slow speeds (approx. 20
MPH), for a very short distance only, the transmission
must be in netural and the transfer case MUST be in
“ TWO WHEEL HIGH.”
When towin the vehicle at faster speeds for reater
distances, the followin steps MUST be taken:
• If front wheels are on the road, disconnect the front
drive shaft.
« If rear wheels are on the road, disconnect the rear
drive shaft.
Both manual and automatic transmissions should be
towed in neutral only, with parkin brakes fully released.
When towin a vehicle on its front wheels only, the
steerin wheel should be secured to maintain a strai ht
forward position.
Push Starts—Trucks Equipped with
Automatic Transmission
Do not attempt to start the en ine by pushin the truck.
Should the battery become dischar ed, it will be neces
sary to use an auxiliary battery with jumper cables to
start the en ine.
CAUTION: To prevent dama e to electrical
system never connect booster batteries in ex
cess of 12 volts and connect positive to positive
and ne ative to ne ative.
Lifting Van With Hoist
Many dealer service facilities and service stations are
equipped with a type of automotive hoist which bears upon
some part of the front and rear axles in order to lift the
vehicle. In Fi ure 4 the shaded portions indicate areas
recommended for hoist contact.
Lifting With Auto Jack
The shaded areas on both the front and the rear axles,
as shown in Fi ure 4 are recommended Van jack liftin
points. The jack load rest must locate under the axle at
these points.
LOAD CAPACITY CHART
New sprin capacities and mandatory equipment options
are included in the Load capacity chart on the followin
pa es.
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-5
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS A D
SCHOOL BUS CHASSIS
10-30 SERIES
Gasoline
Models W heel base GVW
Minimum Mandatory Equipment fo r GVW Ratin
Front
Axle Front
Sprin s Rear Axle Rear
Sprin s
T ir es
Front Rear
133-13580
134-136-13880 116 4300$ 1900 1900 2700 2200 7.35-14-4 fl 7.35-14-4 H
GS/GE 10 90
108
3900$
2200
2250 2400 1900 6.95-14-4 6.95-14-4
4500
3050
RPO G50
7.35-14-8 7.35-14-8
5000 § 2550
RPO F60
2900
RPO H04/
H05 7.00-14-8 7.00-14-8
CS/CE 10
(exc 05, 06, 16
models)
115
127
4400$ 2500 2500 3500 2500 8.15-15-4 8.15-15-4
4800 4000 8.15-15-8 8.15-15-8
5000 § RPO G50 7-17.5-6 7-17.5-6
CS/CE 10
(05, 06, 16 models) 127 4400$ 2500 2500 3500 2500 8.15-15-4 8.15-15-4
5400 § 2700
RPO F60 4000
RPO G50 7-17.5-6 7-17.5-6
KS/KE 10
(exc 05, 06, 16
models)
115
127
4600$ 3300 2900 3300 3600 8.15-15-4 8.15-15-4
5300 8.15-15-8 8.15-15-8
5600 § 7-17.5-6 7-17.5-6
KS/KE 10
(05, 06, 16 models) 127 4600$ 3300 2900 3300 3600 8.15-15-4 8.15-15-4
5800 § 7-17.5-6 7-17.5-6
PS 10 102 4600$ 2500 2500 3500 2500 8.15-15-4 8.15-15-4
5400 § 4000
RPO G50 7-17.5-6 7-17.5-6
GS/GE 20 108 5200$ 2550 3600 3050 7.75-15-8 7.75-15-8
5800 3000 2750
RPO F60 3800
RPO G50 8.15-15-8 8.15-15-8
6200 § 8-16.5-6 8-16.5-6
CS/CE 20
(exc 05, 06, 16
models) 127
5700$
3000 2700 5200 4000 7-17.5-6 7-17.5-6
6200 7-17.5-6 8-17.5-6
6700 6000
RPO G50 7-17.5-6 8-17.5-8
7500 § 8-19.5-6 8-19.5-8
CS/CE 20
(05, 06, 16 models) 127
5700$
3000 2700 5200 4000 7-17.5-6 7-17.5-6
6200 8.00-16.5-6 8.00-16.5-8
6700 3000
RPO G50 6000
RPO G50 8.75-16.5-8 8.75-16.5-8
7500 § 9.50-16.5-6 9.50-16.5-8
KS/KE 20
(exc 05, 06, 16
models) 127
5700$
3500 3200 5200
3800 7-17.5-6 7-17.5-6
6400 5000
RPO G50
8-17.5-6 8-17.5-6
7200 8-17.5-6 8-17.5-8
7500 § 8-19.5-6 8-19.5-8
KS/KE 20
(05, 06, 16 models) 127
5700$
3500 3200 5200
3800 7-17.5-6 7-17.5-6
6400 5000
RPO G50
8.00-16.5-6 8.00-16.5-8
7200 8.75-16.5-6 8.75-16.5-8
7500 § 9.50-16.5-6 9.50-16.5-8
PS/PE 20 125
133
6500$ 3000 3000 5200 4800 7-17.5-6 8-17.5-6
7500 § 6200
RPO G50 8-17.5-6 8-17.5-8
CS/CE 30 133
157
6700$
3500 3000 7200
4800 8-17.5-6 8-17.5-8
7800m# 6200
RPO G50 8-19.5-6 8-19.5-8
9000 3500
RPO F60 8300
RPO G60 7-17.5-6 8-17.5-6D 10000 § 7-17.5-6 8-17.5-8D
14000** 4000
RPO H22 4000
RPO H22 11000 RPO H22 11800
RPO H22 8-19.5-6 8-19.5-10D
PS/PE 30 125
133
157
7500$ 3500 3500 7200 6200 8-17.5-6 8-17.5-8
10000 § 8300
RPO G60 7-17.5-6 8-17.5-8D
14000** 4000
RPO H22 4000 RPO H22 11000
RPO H22 11800
RPO H22 8-19.5-6 8-19.5-10D
Diesel Models
P T 20 125
133 7500$ 3000 3000 5200 6200 8-16.5-6 8-17.5-8
PT 30 125
133
157
7500$ 3500 3500 7200 6200 8-17.5-6 8-17.5-8
10000 § 8300
RPO G60 7-17.5-6 8-17.5-8D
EXTRA P L Y R ATING AND/OR OVERSIZE TIRES AND HEAVIER DU TY CHASSIS EQUIPM ENT AV AILA BLE O PTIO N ALLY.
$ -T ires shown are included **-R PO Z51 GVW plate. § -GVW ratin shown on vehicle ratin plate. Ratin s are H-F70-14 Red Stripe tires on
in the base price. # -Maximum GVW on pickups. increased or decreased in accordance with the minimum Model 13880.
m-R PO Z70 GVW plate. equipment shown on the above chart.
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-6
40-60 SERIES
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS AND
SCHOOL BUS CHASSIS
Gasoline
Models Wheel
base GVW GCW Front
Axle Front Sprin s Rear
Axle Rear Sprin s Minimum Mandatory Equipment
for GVW Ratin
CS/CE 40
also
PS 40
125
137
149
167
157
175
10500$
12000
--
4000 4000 11000 11000
14000 RPO J70 Power Brake Equipment.
15000*
5000
RPO F47 6000 RPO F60
RPO Z71 GVW plate. J70 Power Brake
Equipment.
16000§ 13500
RPO H07
15000
RPO H07 RPO J70 Power Brake Equipment.
18000* 17500
RPO G55 RPO Z85 GVW plate. RPO J70 Power Brake Equipment
TS/TE 40
97
109
133
145
175
10500$
12000
—5000 6000
11000 11000
14000 RPO J70 Power Brake Equipment.
15000* RPO Z71 GVW plate. J70 Power Brake
Equip.
16000§ 13500
RPO H07
15000
RPO H07 RPO J70 Power Brake Equipment.
18000* 17500
RPO G55 RPO Z85 GVW plate.
RPO J70 Power Brake Equipment.
SS 40 149
10500$
14000
15000* —5500 6000
11000 11000 RPO Z71 GVW plate.
16000§ 13500
RPO H07
15000
RPO H07
18000* 17500
RPO G55 RPO Z85 GVW plate.
CS/CE 50
125
137
149
167
173
179
189
203
217
15000*$
16000$
17000
19500§ 32000
(CS)
5000 6000
15000
17500
22000* 7000 RPO F48 7000 RPO F48 20800 RPO G56
RPO Z86 GVW plate.
RPO F03 Heavy Duty Frame.
50000 RPO L86 366 En ine. Z86 GVW plate.
RPO F03 Heavy Duty Frame.
TS/TE 50
97
109
133
145
175
15000*$
16000$
17000
19500§
32000
(TS) 7000 7000 15000 17500
22000* 20800
RPO G56 RPO Z86 GVW plate.
50000 RPO L86 366 En ine. Z86 GVW plate.
MS/ME 50 149
167
185
24000$
30000 -- 7000 7000 28000 30000
CS 60
125
137
149
167
173
179
189
203
217
19000$
24000§ 32000 7000 7000 17000 18400
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-7
40-60 SERIES (CONT’D.)
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS AND
SCHOOL BUS CHASSIS
Gasoline
Models Wheel
base GVW GCW Front
Axle Front
Sprin s Rear
Axle Rear
Sprin s Minimum Mandatory Equipment
for GVW Ratin
125 19000$
137
149
167
173
179
189
203
217
24000§ -- 7000 7000 17000 18400 Z76 GVW plate, Z50 Fr. Reinf, L86
27500* 50000 9000 9000 18500 23000 366 en ine.
CE 60 60000 RPO F43 RPO F94 RPO H66 RPO G58 Z76 GVW plate, Z50 Fr. Rein , L43
32000X 60000 11000
RPO F44 11000
RPO F44 23000
RPO H65 23000
RPO G58
427 en ine.
RPO Z77 GVW plate. RPO F02 Frame
Reinf.
RPO L43 427 En ine.
97
109 19000$
TS 60 133
145
175 24000§ 32000 7000 7000 17000 18400
19000$ 17000 18400
97
109 24000§ 7000 7000 Z76 GVW plate, Z50 Fr. Reinf, L86
TE 60 133 27500* 50000 9000 9000 18500 23000 366 en ine.
145 60000 RPO F43 RPO F94 RPO H66 RPO G58 Z76 GVW plate, Z50 Fr. Reinf, L43
175
32000X 60000 11000
RPO F44 11000
RPO F44 23000
RPO H65 23000
RPO G58
427 en ine.
RPO Z77 GVW plate. RPO F02 Frame
Reinf.
RPO L43 427 en ine.
30000$ 7000 7000
149
167
185
36000§ 30000 34500
ME 60 39000* 9000
RPO F43 9000
RPO F94 RPO Z82 GVW plate.
41000* 11000
RPO F44 11000
RPO F44 RPO Z78 GVW plate.
45000* 60000 34000
RPO H58 39000
RPO H58 RPO Z79 GVW plate. (RPO L43 427
En ine for 60,000 GCW only.)
16000$ 15000
SS/SE 520 189 17000 5500 6000 17500
SS/SE 525 218 19500§ -- 15000 RPO G55
SS/SE 528 235 22000* 7000
RPO F48 7000
RPO F48 20800
RPO G56 RPO Z86 GVW plate.
16000$ 15000
SE 531 254 18000 7000 7000 15000 17500
RPO G55
22000§ 20800
RPO G56
235
254 19000$ 18400
SE 600 23000§
--
7000 7000 17000 20800
RPO G56
25000§$ 45000 7000 7000
127
139
151
169
191
205
217
27500* 51000 9000
RPO F 43 9000
RPO F94 18500 18500 RPO F06 Frame Reinforcements.
29000* 51000 7000 7000 22000 22000 RPO F26 Hi-Tensile Frame on HM 710-
712-714-717-720. RPO F25 heat treated
frame on HM723 and HM725. 11
HM 70 31000* 55000 RPO H74
or H75 RPO H74
or H75
32000*X 55000
9000
RPO F43 9000 RPO F94 23000
RPO H82 24000
RPO H82
RPO F26 Hi-Tensile Frame and RPO
F07 Hi-Tensile Reinf. on HM710-712-
714-717-720. RPO F25 heat treated
frame and RPO F10 heat treated Reinf.
on HM723-725.
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-8
40-60 SERIES (CONT’D.)
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS AND
SCHOOL BUS CHASSIS
Gasoline
Models Wheel
base GVW GCW Front
Axle Front Sprin s Rear
Axle Rear Sprin s Minimum Mandatory Equipment
for GVW Ratin
25500§$ 51000 7000 7000
127 27500* 51000 9000
RPO F43 9000 RPO F94 18500 18500
139 29000* 55000 7000 7000
HM 80 146
151
169
191 31000* 55000 9000 9000
22000
RPO H74
or H75
22000
RPO H74
or H75
RPO F07 Hi-Tensile Frame Reinf. on
HM810-812-813-814-817-820. RPO F10
heat treated frame reinforcements on
HM823-825. T
205
217 32000* 55000 RPO F43 RPO F94 23000
RPO H82 24000 RPO H82 RPO F07 Hi-Tensile Frame Reinf. on
HM810-812-813-814-817-820. RPO F10
32000* 65000 23000
RPO H82 24000 RPO H82 heat treated frame reinforcements on HM 823-825.
24000§$ 45000 7000 7000
97 25500* 45000 18500
TM 70 109
133 27500* 45000 9000
RPO F43 9000
RPO F94 18400
145 29000* 45000 7000 7000 22000
163
175 31000* 55000 9000 9000 RPO H74
or H75 RPO F06 Frame Reinforcements.
32000*X 55000 RPO F43 RPO F94 23000
RPO H82
24000$ 51000 18500 18400
98
109
133
146
163
27500§ 51000
TM 80 31000* 55000 9000 9000
22000
RPO H74
or H75
20800
RPO H74
or H75
32000* 55000 23000
RPO H82 22000 RPO H82
32000* 65000 23000
RPO H82 22000
RPO H82 RPO L29 478M En ine for GVW ratin .
36000§$ 45000 7000 7000 30000
151 39000* 45000 9000 9000 RPO F06 Frame Reinforcements.
JM 70 169 43000* 55000 RPO F43 RPO F94 34000 34000 RPO M61 Aux. Trans, for GVW ratin .
187 45000* 55000 12000
RPO F54 9000
RPO F54 RPO H55 RPO F25 heat treated frame for dump
and on-off road.
36000$ 55000
43000§ 55000 9000
65000 RPO L29 478M En ine for GCW ratin .
151
169
198
210
55000 12000 34000 34000
RPO F07 Hi-Tensile Frame Reinf. on
JM817-817. RPO M61, M65 or M71
Auxiliary Trans, for GVW ratin .
45000* RPO F07 H-Tensile Frame Reinf. on
JM814-817. RPO M61, M65 or M71*
Auxiliary Trans, for GVW ratin . RPO
L29 47 8M En ine for GVW ratin .
JM 80 65000 RPO F54 9000
47000* 65000 9000 38000 38000 RPO L29 478M En ine for GVW ratin .
RPO F07 Hi-Tensile Frame Reinf. on
48000* 65000 12000
RPO F54 RPO G77 RPO G77 JM814-817. RPO F10 heat treated frame
reinforcements on JM821-823.
36000$ 55000 9000
43000§ 55000
65000 RPO L29 478M En ine for GCW ratin .
WM 80 122
140
158
45000* 55000 11000
RPO F44 9000 34000 34000 RPO M61 Auxiliary Transmission for
GVW ratin .
65000 RPO M61 Aux. Trans, for GVW ratin .
RPO L29 478M En ine for GCW ratin .
47000* 65000 9000 38000
RPO G77 38000
RPO G77 RPO L29 478M En ine for GCW ratin .
RPO F08 Frame Reinforcements.
48000* 65000 11000
RPO F44
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-9
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS A D
SCHOOL BUS CHASSIS
50-80 DIESEL MODELS
Diesel
Models Wheel
base GVW GCW Front
Axle Front
Sprin s Rear Axle Rear
Sprin s Minimum Mandatory Equipment for GVW Ratin
CD 50
CG 50
125
137
149
167
173
179
189
203
217
16000$ -- 5000 6000 15000 17500
17000
19500§
22000* 35000
(CG) 7000
RPO F48 7000
RPO F48 20800
RPO G56
RPO Z86 GVW plate.
24000*
(CG)
17000
RPO H21 RPO Z57 GVW plate.
TG 50
97
109
133
145
163
175
16000$ -- 7000 7000 15000 17500
17000
19500§
22000* 35000 20800
RPO G56
RPO Z86 GVW plate.
24000* 17000
RPO H21 RPO Z57 GVW plate.
TD 50
97
109
133
145
175
16000$
-- 7000 7000 15000 17500
17000
19500§ 20800
RPO G56 RPO Z86 GVW plate.
22000*
CD 60
125
137
149
167
173
179
189
203
217
19000$
-- 7000 7000 17000 18400
24000§
TD 60#
97
109
133
145
175
19000$ -- 7000 7000 17000 18400
24000§
HG 70
127
139
151
169
191
205
217
18500$ 7000 7000 17000 17000
24000
25500* 18500
RPO H63 18500
RPO G54 HD brake booster RPO J73.
27500* 9000
RPO F43 9000
RPO F94 HD brake booster RPO J73.
Frame Reinforcement RPO F06.
29000* 7000 7000 22000
RPO H74 22000 RPO G49
31000*
9000
RPO F43 9000 RPO F94
RPO F26 Hi-Tensile Frame HG
710-712-714-717-720. RPO F25
heat treated frame onHG723-725.§
32000*X 23000
RPO H82 24000
RPO H82
RPO F26 Hi-Tensile Frame &
RPO F07 Hi-Tensile Reinf. on
HG710-712-714-717-720. RPO F25.
ADEQUATE TIRES MUST BE SELECTED FOR TOTAL AXLE LOADS TO MEET GVW REQUIREMENTS. SEE TRUCK
TIRE CHART.
$ - Vehicle ratin with base tires.
§ - GVW ratin shown on vehicle ratin plate. Ratin s are increased or decreased in accordance with the minimum
equipment shown in the above chart. * - RPO GVW plate.
# - Because front axle loadin on Tilt cab models could possibly be reater than that of the Conventional models,
front end loadin should be calculated to ensure that the front suspension capacity is not exceeded. If loadin
exceeds the rated capacity of the base front suspension, the optional heavy duty unit must be used.
X - Available on Air Brake (-13) models only. fl- Reinforcements required for dump and off-road application only.
CHEVROLET TRUCK SERVICE MANUAL

GENERAL INFORMATION 0-10
GROSS VEHICLE WEIGHTS FOR 1968 CHEVROLET TRUCKS A D
SCHOOL BUS CHASSIS
50-80 DIESEL MODELS (CONT’D.)
Diesel
Models Wheel base GVW GCW Front
Axle Front
Sprin s Rear Axle Rear Sprin s Minimum Mandatory Equipment for GVW Ratin
JG 70
151
169
198
210
36000$
--
7000 7000 30000
34000
37000
39000* 9000
RPO F43 9000
RPO F94 RPO M63 Auxiliary Transmission.
43000* 34000
RPO H55
F06 Fr. Reinf. JG714-17-20. M63
45000* 12000
RPO F54 9000
RPO F54 Aux. Trans. RPO F25 heat treated frame on
JG714-717-720.
TG 70
97
109
133
145
163
175
18500$
--
7000 7000 17000
18400
24000
25500* 18500
RPO H63
27500* 9000
RPO F43 9000 RPO F94
29000* 7000 7000 22000
RPO H74 RPO F06 Frame Reinforcement.
31000* 9000
RPO F43 9000 RPO F94
32000*X 23000
RPO H82
HV 70
HJ 70 139 151
25500§$
51000
7000 7000 18500 18500
27500* 9000
RPO F43 9000 RPO F94
29000* 7000 7000 22000
RPO H75 22000 RPO H75
31000* 9000
RPO F43 9000
RPO F94 RPO F06 Frame Reinforcements.
32000* 23000
RPO H82 24000 RPO H82
6000 7000 7000 22000
RPO H75 22000 RPO H75 RPO L49 DH637 En ine. This
ratin available on HJ 70 only.
TV 70
TJ 70 97
109
25500§$
51000
7000 7000 18500 18400
27500* 9000
RPO F43 9000
RPO F94
29000* 7000 7000 22000
RPO H75 22000 RPO H75
31000* 9000
RPO F43 9000
RPO F9432000* 23000
RPO H76 24000 RPO H76
6000 7000 7000 22000
RPO H75 22000
RPO H75 RPO L49 DH637 En ine. This
ratin available on TJ 70 only.
JV 70
JJ 70
151
169
187
198
210
36000§$ 51000 7000 7000
3000
34000
RPO H55 34000
39000* 51000 9000
RPO F43 9000 RPO F94
RPO M71 Aux. Trans, for GVW
ratin .
F06 Frame Reinforcements on
JV-JJ 714, 717 and 720.
43000* 51000
45000* 51000 12000
RPO F54 9000 RPO F54
RPO M71 Aux. Trans, for GVW
ratin .
RPO F25 heat treated Frame on
JV-JJ714, 717 and 720.
6000 9000
RPO F43 9000 RPO F94 3000
RPO F25 heat treated Frame on
JJ714-717 and "°0. RPO L49
DH 637 En ine. This ratin avail
able on JJ 70 only.
ADEQUATE TIRES MUST BE SELECTED FOR TOTAL AXLE LOADS TO MEET GVW REQUIREMENTS. SEE TRUCK
TIRE CHART.
$ - Vehicle ratin with base tires.
§ - GVW ratin shown on vehicle ratin plate. Ratin s are increased or decreased in accordance with the minimum
equipment shown in the above chart. * - RPO GVW plate.
# - Because front axle loadin on Tilt cab models could possibly be reater than that of the Conventional models,
front end loadin should be calculated to ensure that the front suspension capacity is not exceeded. If loadin
exceeds the rated capacity of the base front suspension, the optional heavy duty unit must be used.
X - Available on Air Brake (-13) models only. fl - Reinforcements required for dump and off-road application only.
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-11
LUBRICATION (INCL. ENGINE FUEL)
INDEX
Pa e
Crankcase Capacities .................................................... ....... 11
En ine . . ................................................................................... ....... 11
Gasoline En ine 10-30 and 40-40 S e rie s ....................... ....... 12
En ine Oil Recommendations....................................... ....... 12
Oil Filter Replacement - 10-30 ................................... ....... 12
- 40-80 ................................... ....... 12
Oil Viscosity Numbers.................................................... ....... 12
Maintainin Crankcase Oil L e v e l ................................ ....... 12
When to Chan e Crankcase Oil - 1 0 -3 0 ................... ....... 12
- 40-80 ................... ....... 13
Diesel En ine .................................................................... ....... 13
Oil Q u a lity ....................................................................... ....... 13
Oil Chan es....................................................................... ....... 13
Multi-Viscosity Lubricatin O i l s ................................ ....... 14
Cold Weather Operation ................................................ ....... 14
Oil F ilte r.......................................................................... ....... 14
Air Box Drain Tubes ................................................ ....... 14
Fuel F ilt e r ....................................................................... ....... 14
Fuel Strainer.................................................................... ....... 14
Air C lea n ers....................................................................... ....... 14
G o ve rn o r............................................................................. ....... 14
B a tt e ry ................................................................................ ....... 14
Throw Out Bearin ............................................................. ....... 14
Pa e
Crankcase Ventilation System .......................................... 14
Crankcase B reath er....................................................... 14
Tran sm issions....................................................................... 14
P o w er lid e .......................................................................... 14
Turbo Hydra-Matic............................................................. 15
Synchrom esh....................................................................... 15
Four-Wheel D r iv e ................................................................ 16
Wheel Bearin s ................................................................... 16
Rear A x le s ............................................................................. 16
Master C ylin d e r.................................................................... 17
Full Air B r a k e s ................................................................... 17
Hydrovac and Air Over Hydraulic B ra k es....................... 18
Suspension ............................................................................. 18
Steerin .................................................................................... 18
Propeller Shaft Slip Joints ................................................ 19
Universal J o in ts .................................................................... 19
Brake and Clutch Pedals ................................................... 19
Speedometer Adapter............................................................. 19
Parkin Brake Linka e ....................................................... 19
Tachometer - M echanical.................................................... 19
Body Lubrication.................................................................... 19
En ine Fuel (Gas and D ies el)............................................. 19
Lubrication D ia ra m s.......................................................... 20
The 1968 Truck en ine and chassis recommended
lubrication intervals are outlined in this section.
The time or milea e intervals are intended as a uide
for establishin re ular maintenance and lubrication
periods. Sustained heavy duty and hi h speed operation
or operation under adverse conditions may require more
frequent servicin .
E GI E—GASOLI E A D DIESEL
CRA KCASE CAPACITIES
Crankcase Oil Filter
En ine Type With Oil
Filter
Chan e
Without Oil
Filter
Chan e Type Capacity
Standard
(Opt.)
230 Cu. In. L6 (Gasoline) 54 Throw Away 1
250 Cu. In. L6 (Gasoline) 54Throw Away 1
292 Cu<> In. L6 (Gasoline) 6 5 Throw Away 1 (2 Qt.)
307 Cu. In. V8 (Gasoline) 54Repl. Element 1
307 Cu. In. V8 (Gasoline) 40 Series 65Repl. Element 1
327 Cu. In. V8 (Gasoline) 54Repl. Element 1
327 Cu. In. V8 (Gasoline) 50-60 Series 65Repl. Element 1
366 Cu. In. V8 (Gasoline) 8 6 Repl. Element 2
396 Cu. In. V8 (Gasoline) 5 4 Repl. Element 1
427 Cu. In. V8 (Gasoline) 8 6 Repl. Element 2
159 Cu. In. L3 (Diesel) 11.5 9.5 Repl. Element 2
212 Cu. In. L4 (Diesel) 14 12 Repl. Element 2
318 Cu. In. V6 (Diesel) 16 14 Repl. Element 2
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-1
ENGINES (GASOLINE)
(10-30 SERIES)
ENGINE OIL RECOMMENDATIONS
Use only "first line” oils which, accordin to the
label on the can, are (1) intended for service MS, and
(2) automotive manufacturer's tests (includin General
Motors Standard GM 6041-M). The oil chan e interval as
recommended in this section on oils, is based on the
re ular use of this quality of en ine oil. The majority
of the suitable oils currently available are multi
viscosity (e. ., 10W-30) products.
NOTE: Non-deter ent and other low quality
oils are specifically not recommended. The use
of proper en ine oils and oil chan e intervals
are your best assurance of continued reliability
and performance from your Chevrolet en ine.
The use of '‘break-in” oils, “ tune-up” compounds,
“ friction-reducin ” compounds, etc.., in your Chevrolet
en ine are not recommended. However, there are addi
tive supplements available that can be helpful under
certain conditions. For example if hi her deter ency is
required to reduce varnish and slud e deposits, a
thorou hly tested and approved concentrate—“ En ine Oil
Supplement” *—is available.
Checking Oil Level
The en ine oil should be maintained at proper level.
The best time to check it is before operatin the en ine
or as the last step in a fuel stop. This will allow the oil
accumulation in the en ine to drain back in the crankcase.
To check the level, remove the oil au e rod (dip stick),
wipe it clean and reinsert it firmly for an accurate
readin . The oil au e rod is marked “ FULL” and “ ADD
OIL” . The oil level should be maintained in the safety
mar in, neither oin above the “ FULL” line nor below
“ADD OIL” line. Reseat the au e firmly after takin
the readin .
Ventilation Filter
Remove the crankcase ventilation filter (where used) at
each oil chan e (more often under dusty conditions), wash
in kerosene, re-oil with SAE 20W oil and reinstall.
Engine Oil Change Interval
Chan e en ine oil each 4 months,(f) except that if more
than 6,000 miles are driven in a 4-month period, chan e
oil every 6,000 miles. This interval applies to the initial
chan e as well as subsequent oil chan es. The oil chan e
interval for Chevrolet en ines is based on the use of
oils that meet the requirements indicated in the section
on “ En ine Oil Recommendations.” Oil chan e intervals
lon er than 4 months or 6,000 miles will result in serious
reductions in en ine life and may effect Chevrolet’s
obli ation under the provisions of the New Vehicle
Warranty.
Certain atmospheric and/or drivin conditions in
cludin prolon ed operations at sub-zero temperatures
or under extremely dusty conditions, frequent trailer
haulin , and extensive idlin necessitate more frequent
*or “ Hi h Deter ency Concentrate”
oil and filter chan es.f Operation in dust storms may
require an immediate chan e of both oil and filter. See
your Chevrolet dealer for advice on frequency of oil and
filter chan es because of unusual drivin conditions.
A hi h quality MS oil meetin General Motors Standard
GM 6041-M was installed in your en ine at the factory.
It is not necessary to chan e this factory-installed oil
prior to the recommended normal chan e period. How
ever, the oil level should be checked more frequently
durin the break-in period since somewhat hi her oil
consumption is normal until the piston rin s in the
en ine become seated.
Recommended Viscosity
The followin chart will serve as a uide in selectin
the proper oil viscosity. In addition to providin lubri
cation, the correct viscosity helps assure ood cold and
hot startin by reducin friction and thus increasin
crankin speed.
Anticipated Temperatures Viscosity Number
Above Freezin (+32°F.) SAE 20W, SAE 10W-30
Below Freezin and above 0°F. SAE 10W, SAE 10W-30
Below 0°F. SAE 5W, SAE 5W-20
NOTE: When chan in oil consider the antici
pated temperatures for the next 4 months.
• SAE 5W and 5W-20 oils are not recommended
for sustained hi h speed drivin .
• SAE 30 and SAE 20W-40 oils may be used at
temperatures above 90°F.
• SAE 5W-30 oils may be used at temperatures
below 32°F.
• SAE 10W-40 oils may be used at temperatures
between 0 and 90°F.
OIL FILTER REPLACEMENT
Replace filter(f) at first oil chan e and at every second
oil chan e thereafter. This recommendation is based on
the use of en ine oil which meets the requirements in
dicated in the section on “ En ine Oil Recommendations,”
and the use of the applicable A.C. or equivalent quality
replacement oil filter.
40-80 SERIES
ENGINE OIL RECOMMENDATIONS
Hi h quality en ine oils are available at your Chevrolet
Dealer and at many service stations. It is recommended
that you use an oil which, accordin to the label on the
can, is (1) intended for service MS and (2) passes car
makers’ tests or meets General Motors Standard
GM-6041M. Oils conformin to these types contain deter
ent additives.
t In many such situations, oil chan e intervals should not
exceed 2 months, or 3,000 miles, whichever occurs
first, and similarly, filter chan es should not exceed
4 months or 6,000 miles, whichever occurs first.
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-13
Checking Oil Level
The en ine oil should be maintained at proper level.
The best time to check it is before operatin the en ine
or as the last step in a fuel stop. This will allow the oil
accumulation in the en ine to drain back in the crankcase.
To check the level, remove the oil au e rod (dip stick),
wipe it clean and reinsert it firmly for an accurate
readin . The oil au e rod is marked “ FULL” and "ADD
OIL” . The oil level should be maintained in the safety
mar in, neither oin above the “ FULL" line nor below
“ ADD OIL" line. Reseat the au e firmly after takin
the readin .
Ventilation Filter
Remove the crankcase ventilation filter (where used)
at each oil chan e (more often under dusty conditions),
wash in kerosene, re-oil with SAE 20W oil and reinstall.
Engine Oil Change Interval
Chan e en ine oil every 60 days even thou h less than
1,000 miles have been driven. If more than three thou
sand miles are driven in a 60-day period, chan e oil
every three thousand miles. This interval applies to the
initial chan e as well as subsequent oil chan es. An MS
oil, which meets General Motors Standards GM6041M,
was installed in your en ine at the factory. It is not nec
essary to drain this ori inal factory installed oil prior to
the recommended normal chan e period. However, the
oil level should be chacked more frequently durin the
break-in period since somewhat hi her oil consumption
is normal until piston rin s become seated.
Certain drivin conditions, such as dust storms and
frequent drivin on dusty roads, necessitate more fre
quent oil chan es. Your Chevrolet Dealer is qualified to
advise you.
Recommended Viscosity
The followin chart will serve as a uide in selectin
the proper oil viscosity. The proper viscosity helps
assure ood cold startin by reducin friction and thus
increasin crankin speed.
Anticipated Temperatures Viscosity Number
Above Freezin (+32°F.) SAE 20W, SAE 10W-30
Below Freezin and above 0°F. SAE 10W, SAE 10W-30
Below 0°F. SAE 5W, SAE 5W-20
NOTE: When chan in the oil durin the Fall
and Winter season, consider the lowest antici
pated temperature for the next 60 days.
• SAE 5W oil is not recommended for sustained
hi h speed drivin .
• SAE 30 oil should be used when the prevailin
dayli ht temperature is above 90 °F.
*In many such situtations, oil chan e intervals should not
exceed 2 months, or 3,000 miles, whichever occurs
first.
*or “ En ine Oil Supplement”
OIL FILTER REPLACEMENT
Replace 1 quart filter at each oil chan e. This recom
mendation is based on the use of en ine oil which meets
the requirements indicated in the section on “ En ine Oil
Recommendations,” and the use of the applicable A.C. or
equivalent replacement oil filter.
When 2 quart elements are installed, the oil filter
should be replaced at the en ine oil chan e nearest 6000
mile interval or every 4 months, whichever occurs first.
Drivin under severe dust conditions or prolon ed idlin
may warrant replacin the cartrid e more often.
Maintaining Crankcase Oil Level
The Oil Gau e Rod is marked “ Full” and “Add Oil” .
These notations have broad arrows pointin to the level
lines.
The oil level should be maintained between the two
lines; neither oin above the “ Full” line nor under the
“ Add Oil” line.
CAUTION: Do not overfill, after operatin ve
hicle allow a few minutes for oil to return to
crankcase before checkin oil level.
ENGINES (DIESEL)
OIL QUALITY
Satisfactory lon -time operation of Heavy-Duty Diesel
En ines requires the use of deter ent type “ Heavy-duty
Lubricatin Oils” which meet the requirements of Gen
eral Motors Standard GM 6042-M. These oils provide
better lubrications, possess more heat resistance, and
counteract slud e formation more effectively than the
non-deter ent type oils. These oils are rouped in ac
cordance with their ability to meet the service require
ments common to Heavy-Duty en ine operation.
Oil Changes
It is recommended that new en ines be started with
100 hour oil chan e periods. For hi hway vehicles this
corresponds to approximately 3,000 miles and for city-
service vehicles approximately 1,000-2,000 miles. The
drain interval may then be radually increased, or
decreased followin the recommendations of the oil sup
plier until the most practical oil chan e period for the
particular service has been established.
At each oil chan e, besides drainin en ine crankcase,
drain oil filter and oil cooler. An oil cooler, rear drain-
cock is for oil drain.
Solvents should not be used as flushin oils in runnin
en ines. Dilution of the fresh refill oil supply can occur
which may be detrimental.
TYPE USAGE
MIL-L-2104B
(API- DG)
Generally satisfactory for li ht eneral
service with fuels containin less than
0.5% sulphur.
Supplement 1
(s-i)
(API-DM)
All Diesel en ine - Normal service
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-14
NOTE: Oils of hi her additive levels such as
S-3 (API desi nation DS) tend to form excessive
ash deposits that could result in en ine dama e;
such oils are not recommended for use in
Chevrolet Diesel en ines.
Multi-Viscosity Lubricating Oils
Multi-Viscosity lubricatin oils may be used to facili
tate startin when prolon ed exposure of the en ine to
temperature below freezin is unavoidable. Consult your
supplier re ardin the performance characteristics of
this type of oil and obtain his assurance of adequate lub
rication before subjectin the en ine to heavy-duty
service.
Cold Weather Operation
The proper lubricatin oil viscosity rade when operat
in at temperatures above 30°F. is SAE 30. It is permis
sible to use a li hter rade of oil in order to facilitate
startin as shown in the followin table:
AMBIENT VISCOSITY
TEMPERATURE GRADE
Above 30°F SAE 30
+30° to 0°F SAE 20-20W
0° to -20°F SAE 10W
OIL FILTER
See "Oil Filter" under Gasoline En ines.
AIR BOX DRAIN TUBES
With en ine runnin , check for flow of air from air
box drain tubes every 6,000 miles and, if tubes are
clo ed, remove, clean, and reinstall tubes. Air box
drain tubes should be cleaned at tune-up intervals even
thou h clo ed condition is not apparent. If en ine is
equipped with air box drain tank, drain sediment
periodically.
FUEL FILTER
Drain daily and replace every 12,000 miles.
FUEL STRAINER
The frame mounted fuel strainer assembly, located
between the fuel pump and fuel tank should be replaced
every 12,000 miles or oftener if fuel pressure falls below
recommended minimum (35 psi at operatin speed).
AIR CLEANER
NOTE: Under prolon ed dusty drivin condi
tions, it is recommended that these operations
be performed more often.
Oil Bath Type
Check every 12,000 miles (2,000 miles on Diesel
en ines). Clean if necessary, and refill with en ine oil,
SAE 50, when temperature is above freezin and SAE 20
below freezin .
Oil Wetted Paper Element
Inspect air cleaner at 12,000 miles for dust leaks,
holes or other dama e, replace if necessary. If condition
is satisfactory, rotate element 180° from ori inally
installed position. Replace at 24,000 miles.
Oil Wetted Paper Element with
Polyurethane Wrap
Every 12,000 miles inspect air cleaner. Remove poly
urethane wrap and wash in suitable solvent. Check oil
wetted element and replace if necessary. Check every
6,000 miles thereafter until element is replaced.
GOVERNOR
Replace air filter every 12,000 miles.
BATTERY
Every 6,000 miles clean and oil battery terminals and
oil felt washer. Clean top of battery with diluted am
monia or soda solution and flush with clean water. Check
state of char e especially in freezin weather. An under
char ed battery may freeze and break.
THROW OUT BEARING
On trucks equipped with a yoke and shaft type release
lever, the release bearin is lubricated by means of a
hose attached to a rease cup. The rease cup is filled
with a raphite type rease and should be rotated one turn
every 6,000 miles and refilled as required.
CRANKCASE VENTILATION SYSTEM
Valve Type
Every 12,000 miles or 12 months the valve should be
replaced. Connectin hoses, fittin s, flame arrestor and
crankcase breather cap (where used) should be cleaned.
At every oil chan e the sytem should be tested for proper
function and serviced, if necessary.
Crankcase Breather
At each oil chan e, crankcase breather should be
removed and cleaned in suitable solvent. Do not oil
element.
AIR INJECTION REACTOR SYSTEM (A.I.R.)
The Air Injection Reactor system should have the
A.I.R. pump filter serviced and the drive belts inspected
for wear and tension every 12 months or 12,000 miles,
whichever occurs first. In addition, complete effective
ness of the system, as well as full power and perform
ance, depends upon idle speed, i nition timin , and idle
fuel mixture bein set accordin to specification. A
quality tune-up which includes these adjustments should
be performed periodically to assure normal en ine ef
ficiency, operation and performance.
TRANSMISSIONS (10-30 SERIES)
POWERGLIDE TRANSMISSION
EVERY 6,000 MILES-Check fluid level on dip stick
with en ine idlin , selector lever in neutral position,
parkin brake set and transmission at operatin tem
perature. If fluid level is below full mark on dip stick,
add small amount of automatic transmission fluid. Re
check fluid level and a ain add a small amount of fluid
♦Under prolon ed dusty drivin conditions, it is recom
mended that these operations be performed more often.
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-15
if needed to brin level to full mark. DO NOT OVERFILL.
General Motors DEXRON Automatic Transmission
Fluid, Part numbers 1050568, 1050569, 1050570 which has
been especially formulated and tested for use in your
automatic transmission is recommended. Other Auto
matic Transmission Fluids identified with the mark
DEXRON are also recommended.
EVERY 24,000 MILES, (**) more frequently if vehicle
is used to pull trailers, remove fluid from drain plu hole
and add approximately two (2) quarts U.S. Measure,
(1-2/3 quarts Imperial Measure) of new fluid. Operate
transmission throu h all shift ran es and recheck fluid
level as described above.
A drain plu is provided. It is not necessary to remove
the pan unless the fluid has a ‘'burnt" odor or appears
dark in color.
Lubricate shift linka e with water resistant EP chassis
lubricant which meets General Motors specification
GM 6041-M.
Power lide Low Band Adjustment—At the first trans
mission fluid chan e, have your Chevrolet dealer adjust
the Power lide low band.
TURBO HYDRA-MATIC
Lubrication of your Turbo Hydra-Matic will, except
for fluid capacity and filter chan e listed below, follow
the Power lide transmission recommendations. After
checkin transmission fluid level it is important that the
dip stick be pushed all the way into the fill tube.
Every 4,000 Miles
After removin fluid from the transmission sump,
approximately 7.5 pints U.S. measure (6.25 pints Imperial
measure) of fresh fluid will be required to return level
to proper mark on the dip stick.
Every 4,000 Miles
The transmission sump strainer should be replaced.
SYNCHROMESH
The lubricant level in the housin should be checked
every 6,000 miles with unit at operatin temperatures.
Lubricant should be level with bottom of filler plu hole.
“ Multi-Purpose" ear lubricant meetin U.S. Army
Ord. Spec. MIL-L-2105B is recommended if additions
are required to brin up the lubricant level. The “ Gear
Lubricant Viscosity Table” on the followin pa e shows
the proper viscosity lubricant to be used durin vehicle
operation.
TRANSMISSION CONTROLS
The steerin column manual shift mechanism on 1/2
Ton and 3/4 Ton models equipped with 3 speed trans
mission is factory lubricated and should not require
periodic lubrication. However, should the shiftin effort
become noticeably reater, lubricate all linka e points
with en ine oil.
40-80 SERIES
ALLISON AUTOMATIC TRANSMISSION
Every 2,000 miles the fluid level should be checked
and fluid added as described below when necessary.
**This recommendation applies only to 10 Series Models.
For 20-30 Series Models drain period should be every
12,000 miles.
"Use only General Motors Automatic Transmission Fluid
or DEXRON Automatic Transmission Fluid.”
A ood rade of 10W en ine oil may be used tem
porarily in emer encies, but must be replaced with
Automatic Transmission Fluid as soon as possible.
Checking Fluid
1. Start en ine, set parkin brake and move control
lever into ("3-HI” ) position. Run en ine at 1,000
rpm until en ine and transmission have reached
normal operatin temperature.
2. Remove any dirt or ravel from area around in
dicator in ri ht side of en ine compartment. With
en ine runnin at 1,000 rpm remove indicator from
case, wipe clean, reinsert and carefully withdraw
a ain.
CAUTION: Exercise care to prevent dirt from
enterin filler tube when checkin fluid level.
Add fluid only when level reaches L mark (1 qt. low)
on the indicator.
3. With en ine operatin at 1,000 rpm add sufficient
"Automatic Transmission Fluid-Type A” or “ Type
C” —to brin level to full mark on indicator.
CAUTION: Fluid level should never be hi her
than “ F” mark on indicator when fluid is
at operatin temperature. An excessively full
transmission will result in aeration of the fluid.
The expandin fluid may then be forced out of
the filler tube. Sufficient fluid may be lost to
seriously dama e the transmission.
4. Reinstall indicator and turn the cap 1/4 turn to lock.
Draining and Refilling
Transmission lubricant should be chan ed and the
filter replaced after the first 6,000 miles of operation.
Drain, replace the filter, and refill the transmission
every 12,000 miles thereafter if used in normal hi hway
operation; every 12,000 miles, or oftener, if used for
off hi hway operation, city stop-and- o service, or other
severe service. Approximately 9 qts. of fluid are re
quired to refill the transmission after the pan has been
drained. Drain immediately after operation—while fluid
is still warm. Do not flush transmission after drainin .
SYNCHROMESH (INCL. AUX. 4-SPEED)
The lubricant level in the housin should be checked
every 6,000 miles or oftener under severe operatin
conditions and with unit at operatin temperatures, lu
bricant should be level with bottom of filler plu hole.
The followin Table shows the proper viscosity “ Multi-
Purpose” ear lubricant to be used durin vehicle
operation.
GEAR LUBRICANT VISCOSITY TABLE
Outside Temperature Viscosity Lubricant To Be Used
Below 10°F SAE 80
Up to 100°F SAE 90
Above 100°F
Consistently SAE 140
Either SAE 90 “ Multi-Purpose” ear lubricant or
SAE 90 Strai ht Mineral Oil may be used. It is recom
mended that any additions required to brin up the
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-16
lubricant level be made usin the same type of lubricant
as in the housin .
TRANSMISSION CONTROLS
The brake retarder linka e and throttle valve linka e
for Allison Automatic transmissions should be lubricated
periodically. Contact points between rods, idlers, bell
cranks and supports should be lubricated with SAE 10
en ine oil. A lubrication plus is provided in the Auxiliary
4-speed shift tower. Lubricate every 6,000 miles with
chassis lubricant.
FOUR WHEEL DRIVE
NOTE: The two (2) rear lubrication fittin s on
the front axle drive shaft are inaccessible.
Lubrication of this universal joint will require
disassembly of the shaft from the transfer case.
Most lubrication recommendations and procedures for
4 wheel drive equipped trucks are the same for corre
spondin components of conventional drive trucks. Only
the front axle, includin the differential and Cardon joint,
the transfer case, which transmits power from the trans
mission to either front or rear axles, and associated
linka e points and air vents require special procedures.
Front Axle
The front axle should be checked every 6,000 miles and
refilled with SAE 90 “ Milti- Purpose Gear Lubricant
when necessary. With the differential at operatin tem
perature, fill to the level of filler plu hole. If differ
ential is cold, fill to level of 1/2” below the filler plu
hole. Capacity: 5 pt.
Cardon Jofnt
After every 6,000 miles of drivin , remove the slotted
pipe plu s from the ball ends of the axle housin s. Check
lubricant and refill with SAE 140 Multi-Purpose lubricant
meetin U.S. Army Ord. Spec. MIL-L-2105B (1/2 pt. per
joint) is necessary. Replace the pipe plu s securely.
Air Vent Hose
Check vent hose for kinks and proper installation
every 6,000 miles.
Transfer Case
Check the transfer case level every 6,000 miles and,
if necessary, add lubricant to brin to the level of the
filler plu hole. Use SAE “ Multi-Purpose” Gear Lubri
cant, meetin requirements of U.S. Ordnance Spec.
MIL-L-2105B and follow the “ Gear Lubricant Viscosity
Table" on the previous pa e for proper viscosity “ Multi-
Purpose” ear lubricant to be used durin vehicle
operation.
Control Lever and Linkage
Since no rease fittin is provided in the control lever
it is necessary to brush or spray en ine oil on the lever
pivot point and on all exposed control linka e every
6,000 miles.
WHEEL BEARINGS
(10-30 SERIES)
NOTE: Use hi h meltin point wheel bearin
lubricant which meets General Motors Speci
fication #GM 6031M.
FRONT
Due to the wei ht of the tire and wheel assembly it is
recommended that they be removed from hub before
lubricatin bearin s to prevent dama e to oil seal.
Then remove the front wheel hub to lubricate the
bearin s. The bearin s should be thorou hly cleaned
before repackin with lubricant.
Front wheels are equipped with tapered roller bearin s
on all trucks. Wheel bearin s should be lubricated every
30,000 miles. Do not mix wheel bearin lubricants.
CAUTION: “ Lon fibre” type reases should
not be used on roller bearin front wheels.
REAR
The rear wheel bearin s receive their lubrication
from the rear axle. When installin bearin s which
have been cleaned, prelube with wheel bearin rease.
40-80 SERIES
FRONT
Due to the wei ht of the tire and wheel assembly it is
recommended that they be removed from hub before
lubricatin bearin s to prevent dama e to oil seal.
Then remove the front wheel hub to lubricate the
bearin s. The bearin s should be thorou hly cleaned
before repackin with lubricant.
The front wheels are equipped with tapered roller
bearin s on all models and should be cleaned and re
packed with wheel bearin lubricant every 30,000 miles.
REAR
The rear wheel bearin s on all except the trailin
rear axle on MA50 Series receive their lubrication
from the rear axle. When installin bearin s which
have been cleaned, repack with lubricant. On MA50
Series trailin axle, check lubricant level of each wheel
hub every 6,000 miles. When necessary, remove plu
and refill hub to oil level mark with “ Multi-Purpose”
Gear Lubricant meetin U.S. Army Ord. Spec. MIL-L-
2105B as shown in the “ Gear Lubricant” Viscosity chart.
REAR AXLES
(10-30 Series)
Check lubricant level every 6,000 miles. When neces
sary, refill to level of filler plu hole usin “ Multi-
Purpose” ear lubricant meetin U.S. Army Ord. Spec.
MIL-L-2105B as shown in the “ Gear Lubricant Viscosity
Chart” .
On 20 and 30 Series trucks, drain lubricant every
24,000 miles. If vehicle is operated in exceptionally
heavy work or at continuous hi h speeds, the lubricant
should be chan ed every 12,000 miles. It may be neces
sary to chan e lubricant more often if vehicle is used
off road in dusty areas.
CHEVROLET TRUCK SERVICE MANUAL

LUBRICATION 0-17
Positraction
Same as standard axle but use only the special
Positraction lubricant available at your Chevrolet dealer.
40-80 Series
Check lubricant level (includin the inter axle dif
ferential) every 6,000 miles. When necessary, refill to
level of filler plu hole usin “ Multi-Purpose" ear
lubricant meetin U.S. Army Ord. Spec. MIL-L-2105B
as shown in the “ Gear Lubricant Viscosity Chart.”
Drain the lubricant every 24,000 miles. If the vehicle
is operated in exceptionally heavy work or at continuous
hi h speeds, the lubricant should be chan ed every
12,000 miles. It may be necessary to chan e lubricant
more often if vehicle is used off road in dusty areas.
Two-Speed Axies
The shift unit should be filled with lubricant to the
filler openin on the front cover usin SAE 10 en ine
oil. At ambient temperatures below 0°F., use SAE 5W.
The oil level should be checked every 12,000 miles or
3 months, whichever occurs first.
MASTER CYLINDER
Check master cylinder fluid level every 6,000 miles.
If the fluid is low in the reservoir, it should be filled to
a point about 1/4" from the top rear of each reservoir
with GM Supreme No. 11 Hydraulic Brake Fluid or
equivalent.
FULL AIR BRAKES
Compressor
Remove compressor air strainer and inspect or re
place every 6,000 miles or oftener. The element can be
cleaned in kerosene or mineral spirits. Cleaners of the
aromatic compound must not be used. The element
should be squeezed (not wrun ) dry after cleanin .
Draining Air Tanks
Condensation must be drained from all air tanks
daily. To drain tanks properly, leave drain cocks open
until all air escapes and drainin stops. Durin extreme
cold weather operation, it may be necessary to use an
alcohol evaporator to prevent moisture from freezin
in air tanks.
NOTE: Daily drainin is not necessary if truck
is equipped with the optional moisture ejector
valve.
DD Safety Actuator
Every month or after 2,000 miles dependin on type
of operation check safety actuator.
Every year or after each 50,000 miles, dependin on
type of operation, disassemble actuator and clean all
parts. Install new diaphra m, or any other rubber parts,
if they are worn or deteriorated.
Brake Valve
Every Year or 50,000 Miles: Disassemble brake valve
and clean all parts. Install new inlet valves and piston
seal.
Quick Release Valve
Every Year or 50,000 Miles: Disassemble valve, clean
all parts and replace the diaphra m.
Brake Chambers
Every Month or 20,000 Miles: Check travel of brake
chamber push rods and adjust brakes if necessary.
Every Year or 50,000 Miles: Disassemble brake
chambers and clean all parts. Install new diaphra ms.
Drain Cocks
All drain cocks should be periodically checked for
leaka e.
Safety Valve
Every Year or 50,000 Miles: The safety valve should
be removed, disassembled and thorou hly cleaned.
Single Check Valve
Every Year or 50,000 Miles: The check valve should
be dismantled and thorou hly cleaned.
Low Pressure Indicator
Every Month or 10,000 Miles: Check the electrical
connections and the air pressure at which the contacts
close.
Brake Control Valve
Every 200 operatin hours or after 5,000 miles or
once each month, lubricate pedal mechanism. Also check
the lever's linka e for adjustment and/or bindin .
Every 3,600 operatin hours or after each 100,000
miles, clean and replace parts as required.
Every 7,200 operatin hours or after 200,000 miles,
or every two years, disassemble brake valve, clean and
inspect all parts. Install new parts where they are found
to be worn or dama ed.
Automatic Emergency Valve
Every year or after 50,000 miles, the Automatic
Emer ency Valve should be disassembled, cleaned and
lubricated. Rubber parts should be replaced and any
other parts showin si ns of wear or dama e should
also be replaced.
Double Check Valves
Once a year or every 50,000 miles, the check valve
should be removed, dismounted, and cleaned.
Tractor Protection Valve
Thorou hly check and if necessary clean, replace
parts and lubricate.
Double Check Valve and Stop Lamp Switch
Every month or after 10,000 miles, check the electrical
connections and the operation.
Every year or after 50,000 miles, the combined stop
li ht switch and double check valve should be dis
assembled and cleaned and parts replaced as required.
CHEVROLET TRUCK SERVICE MANUAL