Chevrolet 10 Series 1970 Service Manual page 388

EMISSION CONTROL SYSTEMS 6T-4
REAR COVER
H O U S IN G
FILTER FAN
DRIVE HUB
F ig , 4 —A ir In je c tio n Pump
speeds the ex cess a ir is dumped through the pressu re
r e li e f va lve which is part o f the d iv e rte r valve.
The check va lv e s preven t exhaust gases from entering
and damaging the a ir injection pump, as back flow can
occur even under norm al operating conditions.
When p ro p e rly installed and maintained, the A .I.R .
System w ill e ffe c tiv e ly reduce exhaust em ission s. How­
e v e r, if any A .L R . component or any engine component
that operates in conjunction with the A „L R . System should
malfunction, the exhaust em ission s might be increased.
Because o f the relationship between " Engine Tune Up"
and " Unburned Exhaust G ases" , the condition o f the En­
gine Tune Up should be checked whenever the A .I.R .
System seem s to be malfunctioning.
should be taken in checking item s that a ffe c t fu e l-a ir
ra tio such as the crankcase ventilation system , the c a r ­
bu retor and the carb u retor a ir cleaner.
Because o f the s im ila rity o f many parts, typical illu s ­
tration s and proced u res a re used except where sp ecific
illu stration s o r proced u res a re n ecessary to c la r ify the
operation.
DRIVE BELT
Inspection
• Inspect d riv e b elt fo r w ear, cracks or d eterioration
and rep lace if requ ired.
• Inspect belt tension and adjust if below 75 lbs. using
a strand tension gauge.
Adjustm ent
• Loosen pump mounting bolt and pump adjustment
bracket bolt.
• M ove pump until b elt is tight 75 ± 5 lb. used belt or
VENT HOLE
(D O N O T OIL)
ROTOR SHAFT
P a rtic u la r care
MAINTENANCE PROCEDURES
OUTLETS
SIGNAL'
LINE
CO N N ECTIO N
F ig . 5 — D iv e rte r V a lv e (T y p ic a l)
F ig . 6 —C h e ckin g A .I.R . Pump B elt Tension
125 ± 5 lb. new belt using a strand tension gauge)
then tighten adjustment bracket bolt and mounting
bolt (fig. 6).
CAUTION:
Do not pry on the pump housing.
D istortion o f the housing w ill resu lt in extensive
damage to the A ir Injection Pum p.
Replacement
• Loosen pump mounting bolt and pump adjustment
bracket bolt then swing pump until d riv e b elt may be
rem oved.
• Install a new d riv e belt and adjust as outlined above.
PRESSURE
RELIEF
VA LV E
DIVERTED AIR
OUTLET
DIAPHRAGM
ASSEM BLY
CHEVROLET TRUCK SERVICE MANUAL