Chevrolet 1977 light duty truck, Service Manual

Page: 670 / 861

ON VEHICLE SER VICE
C hecking Air C leaner
1. Inspect system to be sure all hoses and ducts are
connected.
2. If en g in e is w arm (above room tem p eratu re)
rem ove air cleaner. P erm it it to cool to room
tem p e ratu re.
3. Install cooled a ir cleaner. If air cleaner has cold
air in tak e hose, disconnect it.
4. S ta rt engine. W atch d a m p e r valve in a ir cleaner
snorkel.
5. W hen engine is first started, valve should be
closed. As air clean er w arm s up, valve should slowly
open.
N O T E : In hot w eath er the room tem p era tu re m ay
be too hot fo r the snorkel valve to close w hen the
engine is started. In this case, cool the tem p eratu re
sensor in the a ir cleaner w ith a cool w et rag.
6. If valve d o e sn ’t close w hen the engine is started,
check for vacuum at the d ia p h rag m .
7. If vacuum is present, check fo r b in d in g in the
d a m p e r valve and o p eratin g link. If d a m p e r moves
freely, replace d ia p h ra g m . (F ailu re o f the d ia p h ra g m to
close is m ore likely to result from m echanical bin d due
to a d a m ag ed or corroded snorkel assem bly than from a
failed d ia p h ra g m . This should be checked first, before
rep lacin g the d iap h rag m ).
8. If no vacuum is present, check hoses for
disconnects, cracks or pinches. R e p air or replace as
necessary.
9. If hoses are OK, replace tem p e ratu re sensor in
the a ir cleaner.
W IN G NUT
TORQUE AT 20 LBS. IN.
I N O T E ] Polyurethane Band must w rap
over both end seals of paper element as
shown.
PO LYW RA P A IR fc ,
CLEANER ELEMENT
(B A N D S H O W N ) ~
AIR CLEANER
ELEMENT _
( PAPER FILTER
PORTION)
n o t e
] Polyurethane Band must
completely cover the outer screen
surface of paper element as shown.
PAPER FILTER PORTION
OF PO LYW RAP AIR
'CLEANER ELEMENT
Fig. 6E-25--Polywrap Air Cleaner Element
Air C leaner E lem en t R eplacem ent
Paper Element
1. R em ove a ir c lean er cover.
2. R em ove elem ent.
3. Install new elem ent in air cleaner w ith eith er
end up.
4. Install a ir cleaner cover. Do not over-torque
w ing nut.
Polywrap Element
1. Rem ove air clean er cover.
2. R em ove elem ent.
3. R em ove polyw rap b an d from p ap er elem ent
an d discard elem ent (Fig. 6E-25).
4. C lean bottom section o f a ir cleaner and inspect
cover seal fo r tears o r cracks. R eplace seal if dam aged.
5. Inspect b an d for tears and replace if dam aged.
6. If band is serviceable, wash in kerosene or
m in e ral sp irits a n d squeeze out excess solvent (Fig. 6E-
26).
N O T E : N ev er use a hot d eg rease r o r any solvent
c o n ta in in g acetone or sim ila r solvent; also, never
Fig. 6E-26-Cleaning Polywrap Band
shake, swing or w ring the elem ent to rem ove excess
solvent as this m ay tear the p o ly u reth an e m aterial.
Instead, "sq u eeze" the excess solvent from the
elem ent.
7. D ip band into light engine oil and squeeze out
excess oil.
8. Install b and around o uter surface o f new p a p e r
elem ent.
9. Install elem ent in bottom section o f air cleaner
w ith eith er end up.
10. Install air cleaner cover. Do not over-torque
w ing nuts(s).