PDF Service Manual 1981 Chevrolet Light Duty Truck Series 10-35 - 5 MB
Restore and maintain your classic 1981 Chevrolet Light Duty Truck with this comprehensive chassis service manual.
Covering the Series 10 through 35, this guide is packed with factory-approved procedures for service and repair.
It includes detailed specifications, diagrams, and troubleshooting steps for all major systems.
This is the same manual used by dealership technicians in 1981, making it an invaluable resource for any owner or mechanic.
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VEHICLE MAINTENANCE SCHEDULE
OWNER'S SERVICE LOG ( M i l . , I ( M
When To Ptrform Services Item 30.000 37,500
7,500 15,000 22,500 45.000
(M l.— •> MHm (kali WMrtmr Occm n Rfst) No. Services (12 000 km) (24 000 km) (36 000 km) (48 000 km) (60 000 km) (72 000 km)
S e c t i o n A —L u b r ic a t io n a n d G e n t r a l M a in te n ance
A-1 ‘ Fluid Levels Check X X | ' X J L L ......... X X1
Every 1 2 M o n th s or 7 ,5 0 0 M iles C lutch Pedal Free Travel Check/Adjust X X X X X
A -2
A -3 *Engine Oil Change X X X * x X X . ..
X
Fig. OB-1 b--Maintenance Schedule, Gasoline, Light Duty Emissions, California
A -4 * 0 i l Filter Change X X
A -5 ‘ Chassis Lubrication
S e e Explanation A -6 F ront W h eel D rive
A -7 Tire Rotation
A -8 R ear A x le Lubrication
Every 1 2 M o n th s or 1 5 ,0 0 0 M iles
A -9 •C o o lin g System C h eck— See Explanation X X
( 2 4 0 0 0 km ) <
A -1 0 W heel Bearing Repack X
Every 3 0 ,0 0 0 M iles (4 8 0 0 0 km ) A -1 1 M anual Steering G ear Seals Check X
A -1 2 Clutch Cross S haft Lubrication X
Every 1 0 0 .0 0 0 M iles (1 6 0 0 0 0 km ) A -1 3 A uto. Trans. Fluid & Filter Change
S e c t i o n B — S a f e t y M a in t e n e n c e
B-1 O w n er Safety Checks X X X X X X
B -2 Tire, W heel and Disc Brake Check X X X X X X
Every 1 2 M o n th s or 7 ,5 0 0 M iles X X X X X
B -3 ‘ Exhaust System Check X
( 1 2 0 0 0 km )
B -4 Suspension and Steering Check X X X X X X
B -5 Brake and Power Steering Check X X X X X X
B -6 •D riv e B elt C h eck (2) X
B -7 Drum Brake and Parking Brake Check X X X
Every 1 2 M o n th s or 1 5 ,0 0 0 M iles X X X
B 8 Throttle Linkage Check
w U km j
B -9 Bumper Check X X X
B-10 *F u e l Cap, Tank and Lines Check X X X
Se ction C — Em ission Control Maintenance Schedule I
C-1 Therm o. Controlled Air Cleaner Check X
A t firs t 6 M o n th s o r 7,5 0 0 M iles
(12 0 0 0 km ) — T h e n 2 4 -M o n th /
C -2 C a rb u reto r Choke & Hoses Check X X (1) xt;
3 0 ,0 0 0 -M ile (48 000 km ) Intervals C -3 Engine Idle Speed A djustm ent X (1) X
MAINTENANCE AND LUBRICATION
as in d icate d in Log, Except C-2 C -4 EFE System Check X X
a n d C-6, W h ich R e q u ire Service C -5 Carburetor M ou n tin g Torque X (1) X
at 4 5 ,0 0 0 M ile s (72 000 km )
C -6 Vacuum Advance System & Hoses Check ---------- X
C -7
PCV System Check xP X xT
E v ery 15,000 M ile s (24 000 km ) PC V Valve R e p la cem en t X
C -8 Spark Plug W ires Check X
C -9 Idle Stop Solenoid an d /o r Dashpot Check ---- X
C -1 0 Spark Plug Replacem ent X (1)
E v e ry 3 0 ,000 M ile s (48 000 km ) C -11 Engine Tim ing Adjust & Distrib. Check X
C -1 2 Air C le a n e r & PC V R e p la cem en t X (1)
* C -1 3 E G R System Check X
▲Also A Safety Service *AI»o An Emission Control Service (1) Only these emission control maintenance items are considered to be required maintenance as defined by the
California Air Resources Board (ARB) regulation and are, according to such regulation, the minimum maintenance an
Hioh Altitude Adjustment: Your 1961 General Motors vehicle has been certified to meet emission standards at low
owner in California must perform to fulfill the minimum requirements of the emission warranty. All other emission
altitude. Certain vehicles sold for high altitude use have been adjusted prior to delivery for improved driveability and
maintenance items are recommended maintenance as defined by such regulation. General Motors urges that all
emission control at high altitude. These vehicles may be identified by additional underhood tune-up label, "Supple
mental Vehicle Emission Control Information." Information regarding adjustment of your vehicle, if permitted, can be emission control maintenance items be performed.
obtained from the Consumer Relations Office shown in the Owner Assistance Section of your Owner's and Driver's (2) A separately driven air pump belt check is recommended but not required at 15,000 miles (24 000 km) and 45,000
Manual. Indud* your Vehicle MentMcation Number in your request. miles (72 000 km).
OB-3
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OB-14 MAINTENANCE AND LUBRICATION
out and/or catch fire, possibly resulting in dam Service
age to the vehicle and its contents and/or per • M aintain cooling system freeze protection at -34°F
sonal injury to its occupants and persons in the (-37°C) to ensure protection against corrosion and loss
area. of coolant from boiling. This should be done even if
freezing tem peratures are not expected.
Truck-Type Snow Tires:
• A dd ethylene glycol base coolant th a t m eets G M
W hen using truck-type snow tires, cold inflation pres Specification 1899-M when coolant has to be added
sures should be increased 10 psi (70 kPa) above the advised because of coolant loss or to provide added protection
pressures for the load being carried. However, do not exceed ag ain st freezing a t tem p era tu res lower th an -34°F
the wheel capacity lim it shown in Section 3E. Sustained (-37°C).
speeds above 65 mph (100 km/h) are not advised.
• Alcohol or m ethanol base coolants or plain w ater alone
3. For proper inflation pressures when towing trailers, the should not be used in a vehicle a t any time.
following is recom mended:
W hen towing trailers on dead-w eight hitches, inflate T he cooling system should be serviced each year
tires to the pressures shown on the C ertification Label (15,000 miles, 24 000 km, on light duty emission service)
(on either the left door latch post or the left door edge (12,000 miles, 19 200 km, on heavy duty emission and diesel
next to the driver) or, if applicable the "T ire Inflation engine vehicle service) as follows:
Pressure" charts in Section 3E. 1. W ash radiator cap and filler neck with clean water.
For trailers using w eight-distributing hitches, increase 2. Check coolant level and test for freeze protection.
front tire pressure 2 psi (14 kPa) above the pressure 3. T est system and ra d ia to r cap for proper pressure
shown on the C ertification Label (or "T ire Inflation holding capacity, 15 psi (105 kPa). If replacem ent cap
Pressure" charts). This increase should never exceed is needed, use a cap designed for coolant recovery
the m axim um pressure shown on the side of the tire. systems and specified model.
It should be rem em bered th a t when a trailer is con
4. Tighten hose clamps and inspect all hoses. Replace
nected, the trailer tongue weight is p art of the load
hoses if swollen, "checked", or otherwise deteriorated.
being carried by the vehicle and, therefore, is included
in the GV W of the vehicle. 5. Clean frontal area of radiator core and air conditioning
condenser.
4. Always use a tire pressure gage (a pocket-type gage is
advised) when checking inflation pressures. A visual
Flush and Refill
inspection of tires for inflation pressures is not enough,
especially in the case of radial tires. U nderinflated Every two years, 30,000 miles (48 000 km) on light
radial tires m ay look sim ilar to correctly inflated radial duty emissions or 24,000 miles (38 400 km) on heavy duty
tires. If the inflation pressure on a tire quite often is emissions and diesel engine vehicles, whichever occurs first,
found to be low, correct the cause. the cooling system should be flushed and refilled as follows:
5. Be sure to reinstall th e tire inflation valve caps, if so 1. Remove radiator cap when engine is cool:
equipped, to prevent d irt and m oisture from getting • Turn cap slowly to the left until it reaches a "stop"
into the valve core which could cause air leakage. (Do not press down while turning the cap).
6. If an air loss occurs while driving, do not drive on the • W ait until pressure is relieved (indicated by a hissing
deflated tire more th an is needed to stop safely. Driving sound); then press down on cap and continue to
even a short distance on a deflated tire can dam age a rotate to the left.
tire and wheel beyond repair.
CAUTION:To help avoid the danger of being
A-8 Rear Axle burned, do not remove the radiator cap while the
engine and radiator are still hot. Scalding fluid
D rain and refill to level of filler plug hole every 7,500 and steam can be blown out under pressure if the
miles (12 000 km ) on light duty emissions or 12,000 miles cap is taken off too soon.
(19 200 km ) on heavy duty emissions when using vehicle to
2. W ith radiator cap removed, run the engine until upper
pull a trailer or severe operating conditions. Use SA E 80W
radiator hose is hot (this shows th at the therm ostat is
GL-5 or SA E 80W -90 G L-5 gear lubricant. In C anada, use
open and the coolant is flowing through the system ).
S A E 80W GL-5 gear lubricant. On 20 and 30 series trucks,
change lubricant every 24,000 miles (38 400 km). 3. Stop engine and open radiator drain valve to drain
coolant. (D rainage may be speeded by removing drain
plugs in the block.)
A-9 Cooling System
4. Close d rain valve (install block d rain plugs, if re
(Also a LD Emission Control Service) moved). Add w ater until system is filled.
The coolant recovery system is standard. The coolant in 5. R epeat steps 3, and 4 several tim es until the drained
the radiator expands with heat, and the overflow is collected liquid is nearly colorless.
in the recovery tank. W hen th e system cools down, the 6. D rain system and then close rad ia to r d ra in valve
coolant is draw n back into the radiator. tightly. (Install block drain plugs, if removed.)
The cooling system has been filled a t the factory with a 7. Remove recovery tan k cap, leaving hoses in place.
quality coolant th at meets G eneral M otors Specification Remove coolant recovery tank and em pty fluid. Scrub
1899-M. The coolant is a 50/50 m ixture of w ater and and clean inside of tank with soap and w ater. Flush well
ethylene glycol antifreeze. with clean w ater and drain. Reinstall tank.
L IG H T T R U C K SE RV IC E M A N U A L
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HEATER 1A-5
INSUFFICIENT HEAT D IA G N O S IS
Position the controls so that the:
Temperature lever is on full heat.
Selector or heater lever is on Heater.
Fan switch is on Hi.
•CHECK DUMP DOOR OUTLET FOR AIR FLOW
NO AIR FLOW AIR FLOW
I ~ I
CHECK DEFROSTER OUTLETS FOR AIR FLOW A d ju st d u m p d o o r fo r n o air flo w . ~|
(If in doubt as to High or Low air flow
set selector on DEF which is High and
compare. Reset selector on Heater)
NO OR LOW AIR FLOW HIGH AIR FLOW
T..............—
CHECK HEATER OUTLET AIR FLOW | Adjust defroster door for low air flow. |
(If in doubt, switch fan
switch from Hi to Lo)
CHANGE IN AIR FLOW LITTLE OR NO CHANGE IN AIR FLOW
NORMAL AIR FLOW | 1 LOW OR NO AIR FLOW~|
Check heater outlet temperature
“ Check shutoff door position for full
with 220° F range thermometer.
system air flow. Adjust if necessary.
(approximate outlet air temperatures)
Outlet Air 145 . 150... 5b ... 165
Ambient Air 0 25 40 75
LOW AIR FLOW | | NO AIR FLOW |
NORMAL TEMPERATURE I
Check heater outlet for obstruction - re | CHECK FUSE |
move.
Remove all obstructions under front seat. I
FUSE BLOWN - replace fuse.
Check motor voltage at closest motor line
Car does not build up heat - operate vent
connection with a voltmeter. I = ;
AIR FLOW - system okay.
controls and see that the air vent doors
close completely, if not, adjust.
LOW TEMPERATURE BLOWS FUSE
UNDER 10 VOLTS OVER 10 VOLTS |
X I
(Check the system temperature after re Remove positive lead from motor and
pairing the item checked to complete the Check battery volts - under 10 volts, replace fuse. ____
diagnosis.) _____ recharge then recheck motor voltage.
Check coolant level; if low, fill. Look for FUSE REMAINS OK - remove motor
or feel all radiator and heater hoses and Check wiring and connections for and check for obstruction in system
connections for leaks. Repair or replace. under 10 volts from motor to fan opening, if none, REPLACE MOTOR.
Check the radiator cap for damage and re switch. Repair or replace last point If obstruction, remove material and
place if required. of under 10 volt reading. re-install motor.
Check heater and radiator hoses for kinks
straighten and replace as necessary. BLOWS FUSE - check for shorted
wire in blower electric circuit -
See Heater Circuit Diagnostic Chart.
Check temperature door for max heat po
sition. Adjust if necessary. Apply external ground, (jumper wire) to
motor case. INCREASED AIR FLOW -
repair ground.
HEATER CORE
FUSE OK
I Feel temperatures of heater inlet and outlet hoses. SAME AIR FLOW - remove motor and
--------------- T ------------- --------------------- check for obstruction in system open
ing. If none, REPLACE MOTOR. If FUSE OK - See Heater Circuit
obstruction, remove material and re Diagnostic Chart.
WARM INLET AND OUTLET HOSES install motor.
Check engine thermostat.
HOT INLET AND WARM OUTLET HOSES ’ CHECK FOR C K MODELS
ONLY
I
Check pulleys, belt tension, etc., for pro 'CHECK FOR G MODELS
per operation. Replace or service as neces ONLY
sary.
X
Remove hoses from heater core. Reverse
flush with tap water. If plugged, repair or
replace.
LIG H T T R U C K SERVICE M A N U A L
--- Page 6 ---
1A-16 HEATER
DIAGNOSIS
R efer to the "S tan d ard H eater" section of this m anual