Chevrolet CHEVY VAN G10 SERIES Service Manual page 211

• Rem ove any carbon build up w ith a wire brush.
• Warped or b u rn ed tubes m ust be replaced.
Replacement
• On in-line engines, remove carbon from tubes an d using
penetrating oil, w ork tubes o ut o f cylinder head.
8
• On V engines, clam p exhaust m anifold in a vise, remove
carbon from tubes an d using penetrating oil, w ork tubes
o u t o f manifold.
A IR INJECTION PUMP
Inspection
A ccelerate engine to approxim ately 1500 RPM and observe
air flow from hose(s). I f air flow increases as engine is
accelerated, pum p is operating satisfactorily. I f air flow does
n o t increase or is n o t present, proceed as follows:
• Check for proper drive b elt tension.
• Check for a leaky pressure relief valve. A ir may be heard
leaking w ith the p u m p running.
N O T E : The A .I.R . System is not com pletely noise­
less. Under normal conditions noise rises in pitch as
engine speed increases. T o determine if excessive
noise is the fau lt o f the A ir Injection
System, operate the engine w ith the pump drive belt
removed. If excessive noise does not exist with the
belt removed proceed as follows:
• Check for a seized Air Injection Pum p.
• Check hoses, tubes, air m anifolds and all connections for
leaks and proper routing.
• Check air injection pum p for proper m ounting.
• If none o f the above conditions exist and the air
injection pum p has excessive noise remove and replace
pum p unit.
Replacement
• D isconnect the hoses at the pum p.
• Remove p um p pulley as outlined.
• Remove p um p m ounting bolts an d remove pum p.
• Install pum p w ith m ounting bolts loose.
• Install pum p pulley as outlined.
• Install and adjust b elt as outlined.
• Connect the hoses at the pum p.
• Tighten m ounting bolts securely.
Pressure Relief Valve
N O T E :
Reactor the diverter valve. The complete u n it must be
replaced to correct a malfunction o f the relief valve.
EMISSION CONTROL SYSTEM 6T-19
The pressure relief valve is incorporated in
C H E V Y V A N S H O P M A N U A L