What You Should Know About Air-Pollution Control - Chevrolet Impala 1969 Owner's Manual

What you should know about Air-Pollution Control
*positive
crankcase
ventilation (pcv)
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8 _ BLOW BY GASES
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COMBUSTIBLE MIXTURE
AIR INTAKE
OPERATION: General Motors vehicles are equipped with
Positive Crankcase Ventilation-a system which permits no
crankcase emission to be discharged into the ambient air.
To function properly, the system depends on the PCV
Valve (smog valve) which recirculates and burns blow·by
gases inside the engine.
MAINTENANCE: This valve must be clean in order to
maintain efficient engine operation. An operational check
of the PCV Valve shou ld be made at the first oil change
(4 months or 6,000 miles, whichever occurs first) . Every
12 months or 12,000 miles, whichever occurs first, the
PCVValve should be replaced (cteaned on Corvairengines).
Also, all hoses, fittings and the inlet air filter should be
inspected, cteaned and replaced, if necessary. Always
specify an AC PCV valve at replacement time.
NOTE:
If the positive crankcase ventilator valve should
become clogged, the engine idle will be adversely affected.
Therefore, if the engine idle becomes too slow or rough,
the venlilator valve should be checked before any carbu-
retor adiustments are made to compensate for the trouble.
"Systems illustrated on V-S engines, 6·cylinder systems similar.