Chevrolet 10 Series 1970, Service Manual

Page: 391 / 671

EMISSION CONTROL SYSTEMS 6T-7
F ig . 14—M o m e n ta ry Blast o f A i r Through D iv e rte r
V a lv e D u rin g Engine O v e r-R u n
DIVERTER VALVE
Inspection
• Check condition and routing o f a ll lin es esp ecia lly
the signal line. A ll lin es must be secure, without
crim p s and not leaking.
• Disconnect signal line at va lv e . A vacuum signal
must be availab le with engine running (fig . 13).
• W ith engine sta b ilized at idle speed, no a ir should
be escaping through the m u ffler. Manually open and
quickly close the th rottle, a m om entary blast o f a ir
should discharge through m u ffler fo r at lea st one
second (fig , 14).
• D efective va lv e s should be replaced.
CAUTION: D iv e r te r v a lv e s although som etim es
s im ila r in appearance a re designed to m eet
p a rticu lar requ irem en ts o f variou s engines,
th e re fo re , be sure to install the c o rre c t va lve.
Replacem ent
• Disconnect vacuum signal line. D isconnect va lve
exhaust h ose(s).
• R em ove d iv e rte r va lve fro m pump.
• Install d iv e r te r va lve to pump o r bracket with new
gasket. Torqu e va lve attaching screw s to 85 in. lbs.
• Install outlet and vacuum signal lin es and check s y s ­
tem fo r leaks.
AIR INJECTION TUBE
Inspection (Fig. 1 5)
• T h ere is no p erio d ic s e r v ic e o r inspection fo r the
a ir injection tubes, yet on V8 engines whenever the
exhaust m anifolds a re rem oved, inspect the a ir
injection tubes fo r carbon build up and warped o r
burnt tubes.
• Rem ove any carbon build up with a w ire brush.
• W arped or burnt tubes must be replaced.
Replacement
• On V8 engines clamp exhaust m anifold in a vis e , r e ­
move carbon fro m tubes and using penetrating oil,
w ork tubes out o f m anifold.
• Install new tubes in m anifold.
AIR INJECTION PUMP
Inspection
A c c e le ra te engine to approxim ately 1500 R P M and ob­
s e rv e a ir flow fro m h ose(s). If a ir flow in crea ses as
engine is accelera ted , pump is operating sa tis fa c to rily .
If a ir flow does not in crease o r is not p resent, proceed
as follow s:
• Check fo r p ro p er d rive belt tension.
• Check fo r a leaky p ressu re r e lie f va lve. A ir may be
heard leaking with the pump running.
NOTE: The A .I.R . System is not com pletely
n oiseless. Under norm al conditions noise r is e s
in pitch as engine speed in creases. T o d e te r­
mine if ex c e s s iv e noise is the fault o f the A ir
In jector R ea ctor System, operate the engine
with the pump d riv e b elt rem oved. If ex c e s s iv e
noise does not exist with the belt rem oved p ro ­
ceed as follow s:
• Check fo r a s e ized A ir Injection Pump.
• Check hoses, tubes, a ir m anifolds and a ll connec­
tions fo r leaks and p ro p er routing.
• Check a ir injection pump fo r p rop er mounting.
• If none o f the above conditions exist and the a ir in ­
jection pump has ex c e s s iv e noise rem ove and r e ­
place pump unit.
Replacem ent
• D isconnect the hoses at the pump.
• Rem ove pump pulley as outlined.
• R em ove pump mounting bolts and rem ove pump.
• Install pump with mounting bolts loose.
• Install pump pulley as outlined.
• Install and adjust belt as outlined.
• Connect the hoses at the pump.
• Tighten mounting bolts secu rely.
Pressure Relief V a lv e Replacem ent
NOTE:
The p ressu re r e lie f va lve is in c o rp o r­
ated in the d iv e r te r va lve. The com plete unit
must be replaced to c o rre c t a malfunction o f the
r e lie f valve.
CHEVROLET TRUCK SERVICE MANUAL