Drive Belts; Positive Crankcase Ventilation; Air Injection Reactor System; Controlled Combustion System - Chevrolet 1974 Light Duty Truck Service Manual

effectively and economically solve certain specific
problems without causing other difficulties. For example,
if higher detergency is required to reduce varnish and
sludge deposits resulting from some unusual operational
difficulty, a thoroughly tested and approved additive -
"Super Engine Oil Supplement"- is available.

Drive Belts

Drive belts should be checked every 6,000 miles or 4
months for proper tension. A loose belt will affect water
pump and generator operation.

POSITIVE CRANKCASE VENTILATION

VALVE
Every 24,000 miles or 24 months the valve should be
replaced. Connecting hoses, fittings and flame arrestor
should be cleaned. At every oil change the system should
be tested for proper function and serviced, if necessary.
AIR INJECTION REACTOR SYSTEM (A.I.R.)

CONTROLLED COMBUSTION SYSTEM

(C.C.S.)
The Air Injection Reactor system should have the drive
belt inspected for wear and tension every 4 months or
6,000 miles, whichever occurs first. In addition,
complete effectiveness of either system, as well as full
power and performance, depends upon idle speed,
ignition timing, and idle fuel mixture being set
according to specification. A quality tune-up which
includes these adjustments should be performed
periodically to assure normal engine efficiency, operation
and performance.
EXHAUST GAS RECIRCULATION SYSTEM
(EGR) -
At 12-month/12,000 mile intervals when operating with
leaded fuels or at 24-month/24,000 mile intervals when
using unleaded fuels remove, inspect, and if deposits
exist, clean the EGR valve. Inspect the EGR passages in
the inlet manifold and clean as required. A damaged
EGR valve must be repaired or replaced.

GM EVAPORATION CONTROL SYSTEM

Every 24 months or 24,000 miles (more often under
dusty conditions) the filter in the base of the canister
must be replaced and the canister inspected.

MANIFOLD HEAT CONTROL VALVE

First 6,000 miles and every 12,000 miles or 12 months
thereafter check valve for freedom of operation. If valve
shaft is sticking, free it up with GM Manifold Heat Con­
trol Solvent or its equivalent.

AIR CLEANER

Do not remove the engine air
CAUTION:
cleaner unless temporary removal is necessary
during repair or maintenance of the vehicle.
GENERAL IN FO R M ATIO N AND LUBRICATION
When the air cleaner is removed backfiring can
cause fire in the engine compartment.
NOTE: Under prolonged dusty driving
conditions, it is recommended that these
operations be performed more often.
011 Wetted Paper Element Type
L-6 engine, replace every 12,000 miles. V-8 engine, every
12,000 miles inspect element for dust leaks, holes or
other damage. Replace if necessary. If satisfactory,
rotate element 180° from originally installed position.
Replace at 24,000 miles. Element must not be washed,
oiled, tapped or cleaned with an air hose.
Crankcase Ventilation Filter
(Located Within Air Cleaner)
If so equipped, inspect every oil change and replace if
necessary. Replace at least every 24,000 miles; more
often under dusty driving conditions.

FUEL FILTER

Replace filter element located in carburetor inlet every
12 months or 12,000 miles whichever occurs first, or, if
an in-line filter is also used, every 24,000 miles. Replace
in-line filter every 24,000 miles.

DISTRIBUTOR

Replace cam lubricator at 24,000 mile intervals.

GOVERNOR

The attaching bolts should be kept tight, the optionally
available governor should be kept clean externally and
the filter element should be replaced every 12,000 miles.

ACCELERATOR LINKAGE

Lubricate with engine oil every 24,000 miles as follows:
1. On V8 engine, lubricate the ball stud at the
carburetor lever.
2. On L6 engine, lubricate the two ball studs at the
carburetor lever and lubricate the lever mounting
stud. Do not lubricate the accelerator cable.
AUTOMATIC TRANSMISSION
FLUID RECOMMENDATION
Use only automatic transmission fluids identified with
the mark DEXRON®—II or DEXRON®(or equivalent).
Check the fluid level at each engine oil change period.
To make an accurate fluid level check:
1. Drive vehicle several miles, making frequent starts
and stops, to bring transmission up to normal
operating temperature (approximately 180-190°F).
2. Park vehicle on a level surface.
3. Place selector lever in "Park" and leave engine
running.
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LIGHT DUTY TRUCK SERVICE MANUAL