engine DATSUN 210 1979 Service Manual

Emission
Control

System

CRANKCASE
EMISSION
CONTROL
SYSTEM

DESCRIPTION

This

system
returns
blow
by

gas
to

both
the

intake
manifold
and
carbure

tor
aitdeaner

The

positive
crankcase
ventilation

P

C
v
valve
is

provided
to

conduct

crankcase
blow

by
gas
to
the
intake

manifold

During
partial
throttle

operation
of

the

engine
the
intake
manifold
sucks

the
blow

by
gas
through
the
P

C
V

valve

Normally
the

capacity
of
the

valve

is

sufficient
to
handle

any
blow

by
and

a

small
amount
of

ventilating
air

L

J

J

o

I

Fresh

air

Blow

by
gas
The

ventilating
air
is

then
drawn

from

the
dust
side
of
the
carburetor

air

cleaner

through
the
tube
connect

ing
carburetor
air

cle
er
to
rocker

cover
into
the
crankcase

Under
full
throttle
condition
the

manifold
vacuum
is

insufficient
to

draw
the

blow
by
flow

through
the

valve
and
its

flow

goes

through
the

tube
connection
in
the

reverse
direc

tion

On
cars
with
an

excessively
high

blow
by
some
of
the
flow
will

go

through
the
tube
connection

to
car

buretor
air

cleaner
under
all
condi

tions

r

IiI
e
1

LJ

1

Seal

type
oil
level

gauge

2
DafOe

plate

3

Flame
arrester

4
Filter

5

P
C
V
valve

6
Steel
net

1
Baffle

plate

EC871

Fig
EC
5
Crankcase
Emis
ion
Control

Sy
tem

EC
6
INSPECTION

p
C
V
VALVE
AND
FILTER

With

ei
gine

runnirig
at
idle
remove

the
ventilator
hose
from
P

C
V

valve

if
the
valve
is

working
a
hissing
noise

wiD
be
heard

as
air

passes
through
the

valve
and
a

strong
vacuum
should
be

felt

irnniediately
when
a

fmger
is

placed
over
valve
inlet

EC139A

Fig
EC
6

Checking
PC

V
Vo
ve

VENTILATION

HOSE

I
Check
hoses

and
hose
connec

tions
for
ieaks

2
oisconn
ct
all
hoses
and

clean

with

compressed
air

If

any
hose

cannot
be

free
of

obstructions

replace

Ensure
that
flame

arrester
is

surly

inserted
in

hose
between

air
cleaner

and
rocker
rover

ET277

Fig
EC

7

Checking
Ventilation
Hose

Emission
Control

System

EARLY
FUEL
EVAPORATIVE
E
FE

SYSTEM

DESCRIPTION

@
jl
D

W

o

0
0
UL
@

1

Intake
manifold

9
Screw

2

Stove

gasket
10

Thermostat

spring

3
Mar
fold
stove
11

Heat
control
valve

4
Heat
shield

plate
12
Control

valve
shaft

5

Snap
ring
13
Exhaust

manifold

6

Countczwcight
14

Cap

7

Key
15

Bushing

8

Stopper
pin
16

Coil
spring

The

early
fuel

evaporative
system
is

provided
with
a
chamber
above
a

manifold
stove
mounted
between
the

intake
and
exhaust

manifolds

During

engine
warming
up
air

fuel
mixture
in

the
carburetor
is

heated
in

the
cham

ber

by
exhaust

gas
This
reuslts
in

improved
evaporation
of
atomized
fuel

droplets
in

the
mixture

and
in

smaller

content
of

hydrocarbons

HC
in
the

exhaust

gas

especially
in
cold
weather

operation

OPERATION

The

counterweight
rotates
counter

clockwise
and

stops
at

the

stopper
pin

mounted
on

the
exhaust
manifold

while
the

engine

temperature
is
low

With
this
condition

the
heat
control

valve
is
in

the

fully
closed

position

obstructing
the
flow

of
exhaust

gas
As

engine

temperature
goes

up
and
the

ambient

temperature
becomes

high

enough
to
actuate

the
thermostat

spring
the

counterweight

begins
to
j

@

l

7

1
1

5

If

@

I

Exhaust
gas
flows

valve
dosed

valve

opened

EC247

Fig
EC

8
Early
Fuel

Eaaporatiae
E
F
E

System

rotate
clockwise
and

again
comes
into

contact

with
the

stopper
pin
With
this

condition
the

heat
control
valve
is
in
the

full

open
position
and
exhaust

gas

passes
through
the

exhaust
manifold

without

heating
the
manifold
stove

REMOVAL
AND
INSTALLATION

1

Snap
ring

2
Lock
bolt

3

Key

4

Counterweight

5
Thermosta
t

spring

6
Coil

spring

7

Heat
controlvalve

EC913
8
Valve
shaft

Fig
EC

9
KF
E

Sy
tem
Component

EC

8

Remove

snap
ring
CD
and
lock
bolt

@
and
the

following

parts
can
be

detached
from
heat

control
valve

shaft

Key

ID

Counterweight

@

Thermostat

spring

@

Coil

spring

@

Note
As

previously
descnbed

heat

control

valve

j
is

welded

to
valve

shaft

@
at

exhaust
manifold

and

cannot
be
disassembled

To
install

reverse
the
removal

procedure

INSPECTION

1
With

engine
stopped
visually

check
the

quick
heat
manifold

system

for
the

following
items

I
Check
heat
control
valve
for

malfunction
due

to
break
of

key
that

locates

counterweight
to
valve
shaft

2
Rotate
heat
control
valve
shaft

with

fingers
and
check
for

binding

between
shaft
and

bushing
in

closing

and

opening
operation
of

heat
control

valve
If

any
binding
is
felt
in

rotating

operation
move
valve
shaft
in
the

rotation

direction
several
times
If
this

operation
does
not
correct

binding

condition
it
is

due
to
seizure
between

shaft
and

bushing
and
exhaust
mani

fold
should

be

replaced
as
an

assem

bly
Emission
Control

System

Counterweight

Heat
control
valve

Stopper
pin

EC249

Fig
EC
IO

Checking
Heat
Control

Valve
Movement

2
Run

engine
and

visually
check

counterweight
to
see
if
it

operates

properly

I
When

engine
speed
is
increased

discharge

pressure
of

exhaust

gases

causes

counterweight
to

move

down

ward

clockwise

2
For

some
time

after

starting

engine
in

cold
weather

counterweight

turns
counterclockwise
until
it

comes

into

contact
with

stopper
pin
installed

to

exhaust
manifold

EC
9
Counterweight
gradually
moves

down

clockwise
as

engine
warms

up

and
ambient

temperature
goes
higher

around
exhaust
manifold

If
it
does
not
move
at
all
check

and

replace
thermostat

spring

AIR

INJECTION

SYSTEM
A

I
S

DESCRIPTION

The
Air

Injection
System
A
I
S

is

adopted
on
U
S
A

models

except
FU

models

and

injects
compressed
air

secondary
air

coming
from
the
air

pump
into

the
exhaust

port
of
the

cylinder
head
to
reduce

hydrocarbons

He
and

carbon

monoxide
CO
in

exhaust

gas
through
recombustion

There

are
two

types
of
Air

Injection

System

Fresh
outside
air
is
drawn

by
the
air

pump
through
the

air

pump
air

cleaner

Compressed
air
is

injected
into

the

exhaust

manifold

through
the

check
valve

The
A
B

valve

supplies
air
from
the

carburetor
air
cleaner
to
the

intake

manifold

so
as

to

prevent
after

fire

during
deceleration

The
amount

of

injected
air
is
con

trolled

by
C
A

C
valve

California

models
or
air

relief
valve

Non

California
models

Emission
Control

System

r

@
@
CD

L

I

1
Air

pump
drive
hub

5
V
ne

2

Housing
6
Carbon
shoe

3
Rotor

rins
7
Shoe

spri
ng

4

End
cover
8

Stripper

with
needle

bearing
9
Rotor
shaft

Anti
backfire
A
B
valve

This
valve
is
actuated

by
intake

manifold
vacuum
to

prevent
backfire

in
the

exhaust

system
at
the

initial

period
of
deceleration

At

this

period
the
mixture
in
the

intake
manifold

becomes
too
rich
to

ignite
and
burn
in

the
combustion

chamber
and

burns

easily
in

the
ex

haust

system
with

injected
air

in
the

exhaust
manifold

The
A

B
valve

provides
air
to
the

intake
manifold
to

make
the
air

fuel

mixture

leaner
and

prevents
backfire

To
in
take

manifold

vacuum

EC069

Fig
EC

15
A
B
Valve
10
Ball

bearing

11
Front

bearing
cOYer

12

Pulley

13

Pulley

for
air
conditioner

Check
valve

A

check
valve
is

located
in
the

air

pump
discharge
lines
The
valve

pre

vents
the

backflow
of
exhaust

gas

which
occurs
in

the

following
cases

I

When
the
air

pump
drive
belt

fails

2
When

relief
valve

spring
fails

1

11
rom

pump

1

Spring

2
Rubber
valve

3

Seat
SecondarY
air

4
J
Exhaust

gas

EC322

Fig
EC

16
Check
Valve

Air

gallery

The

secondary
air

fed
from
the
air

pump
goes

through
the
check
valve
to

the

air

gallery
in
the

cylinder
head
It

EC
lt
14
Inlet

cavity

15

Outlet
cavity

EC066A

Fig
EC
14
Air

Pump
two
vane

lype

is
then

distributed
to

each
exhaust

port
and

injected
near
the

exhaust

valve

0

iJl

Ai

gallery

2

Exhaust

port

3
Exhaust

manifold

EC316

Fig
EC

17
Air

Gallery

Air
pump
relief
valve

Non
California

models

The
air

pump
relief

valve
controls

the

injection
of

secondary
air
into

the

exhaust

system
when
the

engine
is

running
at

high
speed
under
a

heavily

loaded

condition
It

accomplishes
the

following
functions
without

affecting

the

effectiveness
of
the

exhaust
emis

sion
control

system

Minimizes
exhaust

gas
tempera

ture
rise

2
Minimizes

horsepower
losses
reo

sulting
from
air

injection
into
the

exhaust

system

3

Protects

pump
from
excessive

back

pressure

To
carburetor

air
cleaner

Secondary

ir

Not
actuated

To
carburetor

air
cleaner
J

l
Secondary

sir

Actuated

EC294

Fig
EC
18
Air

Pump
Relief
Valve

c
A
C
valve

Californiamodels

The
C
A
C
valve

controls
the

quantity
of

secondary
air
fed
from
the

air

pump
according
to
the
load
condi

tion
and
it

discharges
the

secondary

air
into
the

atmosphere
to

prevent

overheating
of

the

catalytic
converter

This
valve
is

operated
by
intake

manifold
vacuum

and
air

pump
dis

charge

pressure
When
intake
manifold

vacuum
is

small
or
in

the

high
load

range
the
No
2
valve

opens
when
it
is

great
or
in

the
low
load

range
the
No

I

valve

opens
If
air

pump
discharge

pressure
is

large
or
the

engine
is

running
at
a

high
speed
the
No
3

valve

opens
admitting
the
air

pump

discharge

pressure
to
the
No
2
dia

phragm
chamber
of
the
C

A
C
valve
mission
Control

System

and

opening
ihe
No
i
valve
At
this

point
the
No
2
valve

serves
as
a

relief

valve

F
111

air
pump
No
3

valve

EC787

Fig
EC
19

C
A
C
Valve

I
Engine
in
low

speed
and

light
load

When
the

engine
is

operating
under

these
conditions
intake
vacuum
is

high
The
No
2
valve
unitized

with

the
No
I

diaphragm
is

lifted

by
the

intake

manifold
vacuum

pushing
up

the
No
I

valve
These
valves
will
then

stop
at
a

position
where
a

balanced

condition
exists
between
air

pump

discharge
pressure
an
d

spring
tension

acting
on
the

No
I

and
No

2
valves

The

No
2

jiaphragm
however
does

not
move
due

to
low

engine
speed
low

air

pump
discharge
pressure
and

spring

tension

acting
on
the
No

3
valve
For

this
reason
these
valves
are

brought
to

a
balanced
condition

To
intake
manifold

t

i

l

3

Spring

4

ValveNo
3

5
Di

phragm
No
I
I

@

6

Spring

7

Valve
No
1

8
Valve
No

2

EC683

Fig
EC

20

Operation
of
C
A
C

Valve

1

2

Engine
in

low

speed
and

heavy
load

EC12
Wheo
the

engine
is

operating
under

these
cooditions

intake
manifold

vacuum
is
low
and

all
valves

are

balanced

t
To

intake

manUol

U

E

ii

ji
j

Ii
5

LL

jj

Ii
JI

l
Jij

ulJC

1t

To

atmosphere
EC685

Fig
EC
21

Operation
of
C
A
C

Valve
2

3

Engine
in

high
speed
and

middle

load

When
the

engine
is

operating
under

these
conditions
intake

manifold

vacuum
lies

midway
between
1

and

2

above
The
No
3
valve

moves
to

the
left

because
of

high
air

pump

discharge
pressure

To

intake
manifold

t

L

J

f
E

bt

I
5

tfi
11

I

LJr

To

tmg
J
j
1

EC
4

Fig
EC
22

Operation

of
C
A
C

Volve
3

REMOVAL
AND

INSTALLATION

Air
pump
air
cleaner

Loosen

nuts

securing
air

pump
air

cleaner
to

bracket
then
detach
air

cleaner
from
bracket

Air
cleaner
filter

and
air
cleaner
lower

body
are
built

into

a
unit
construction

Replace
air

cleaner
filter
and
lower

body
as
an

assembly

EC149A

Fig
EC

23

Removing
Air
Cleaner

Filter

Air

pump

1
Remove
air

hoses
from

air

pump

2
Remove
air

pump
pulley

3
Loosen
air

pump
adjusting
bar

mounting
bolts
and
air

pump
mount

ing
bolts
then
remove
air

pump
drive

belt

4
Air

pump
assembly
can
be
taken

out
from
bracket

5

Installation
is
in

the
reverse
se

quence
of
removal

Fig
EC
24

Removing
Air

Pump

Check

valve

1
Disconnect
air

hose
from
check

valve

2

Remove
check
valve
from

engine

cylinder
head

3

Installation
is
in

the
reverse
se

fluence
of
removal
Emission

Control

System

EC151A

Fig
EC
25

Removing
Check
Valve

A

B
valve

A
B
valve
is

located
at
the

rear
side

of
air

cleaner
Remove
air

hoses
and

vacuum
tube
A
B
valve
can
then
be

taken
out

EC152A

Fig
EC
26

Removing
A
B
Valve

Air

pump
relief
valve

Non
California
models

I

Loosen

clamp
of
air

hose
and

disconnect
air

hose
from
relief
valve

EC
13
2
Remove
screws

securing
relief

valve
to
air

cleaner
Relief

valve
can

then

be
taken

out
easily

3
Installation
is
in
the
reverse
se

quence
of

removal

EC153A

Fig
EC
27

Removing
Air

Pump

Relief
Valve

C
A
C
valve

California
models

C
A
C

valve
is
located
beneath
con

trol

device
bracket

Remove

clamps
and

disconnect

air

hoses
and
vacuum
tube

2

Remove
screws

securing
C
A

C

valve
Air
control
valve

can
then
be

taken
out

easily

3
Installation
is
in
the

reverse
se

quence
of
removal

EC154A

Fig
EC
28

Removing
C
A
C
Volvo

them

b
If
carbon
shoes
are

exposed
beyond

the
rotor
end
face
remove
carbon

shoes
and
clean
shoe

grooves
Reas

semble
carbon
shoes

6

Vane

1
Pack

vane

bearing
with

high

melting

poinf
grease
MIL
G
3S45
A

Es

o
ANDOK260
or

equivalent
and

insert

dummy
shaft
into
the
vane

bearing

STl9900000

EC563

Fig
EC
40

Va
Assembly

2
Install
vane
in

place
on
rotor

uMng
Dummy
Shaft
STl9900000
as
a

guide

Note
The
woes

may

require
6
to
16

km
4
to
10
miles
wear
in
running

time
In
the
event

a

slight
squeaking

still
remains
drive
the
car

about
64

to
80

km
h
40
to
SO
MPH
In

most

cases
6

to
16
km
4
to
10

miles
will
be
sufficient
for
wear
in

7

Shoe

spring

Place
shoe

springs
in

deeper
groave

of
shoe

11

I

11

1

EC123

Fig
EC
4I
Ins

tolling
Shoe

Spring

Note
When

installing
a

shoe

spring

make
sure
that
the
outward
bend

ing
side
faces
in
shoe
and
that
both

ends
of

sJlri
face
in
the
wall
of
Emission
Control

System

shoe

groove
6e
Sure
to

push
spring

in

SO
that

spring
end
face
is
flush

with
rotor

8
Rotor

ring

Install
rotor

ring
by
correctly

align

ing
the
rear
end
face
of
rotor
with

the

on

mark
in
rotor

ring
and

tighten

screws
with

Hexagon
Wrench

ST
98
10000

l
l
Tightening
torque

Rotor

ring
screw

0
5
to
0

7

kg
m

13

6
to
5
1
ft
lb

Fig
EC

42
Installing
Rotor

Ring

9
Removal
of

dummy
shaft

CarefuDy
withdraw

dummy
shaft

from
vane

10
Vane
shaft

Pack
rear

bearing
with

high

melting

pain
t

grease
MIL
G
3S45
A

Esso
ANDOK
260
or

equivalent

Apply
thin

coating
of

grease
to
vane

shaft
and

rotor
ring
and
insert

vanf

shafi
into
its

bearing

Note

a

Do
not

apply
an
undue
stress
to

vane
shaft
when

inserting

b
If
two
vanes
are
dislocated
when

inserting
vane
shaft

correctly
align

Yanes

by
inserting
dummy
shaft

Then
draw
out

dummy
shaft
and

insert
vane
shaft

c
When
wear
occurs
on

vane
shaft
or

when

replacement
of
rear

bearing
is

necessary
replace
rear
rover
assem

bly

J
I

End
cover

Position
end

cover
in

place
Snugly

tighten
the
bolt
close
to
the
dowel

Then

tighten
end
cover

bolts

EC
t6
l
l
Tighteningtnrque

End
cover
bolts

0
7
to
0
9

kg
m

5
1

to
6
5
ft
bl

EC302

Fig
EC
43
lnstolling
End
Cover

12

Pulley

Tighten

pulley
securing
bolts

Tightening
torque

Pulley
securing
bolts

0
75

to
0
90

kg
m

5
4

to
6
5
ft

Ib

INSPECTION

The
following

procedures
are
re

commended
for

checking
and
or

as

certaining
that
the
various

components

of
the

exhaust
emission
control

system

are

opera
ting
properly

The

engine
and
all

components

mu
t
be
at
normal

operating

tempera

tures
when
the
tests
are

performed

Prior
to

performing
any
extensive

diag

nosis
of
the
exhaust
control

ystem
h

must

be
determined
that
the

engine
as

a
unit
is

functioning
properly

Air

injection
s

stem
hoses

Check
air

system
hoses
for
loose

connections
cracks
or
deterioration

Retighten
01

replace
if

necessary

Air

pump

I

Operate
engine
until
it
reaches

normal

operating
temperature

2

Inspect
all
hose
hose
connec

tions
and
air

gaDery
for
leaks
and

correct
if

necessary
before

checking

air

injection

pump

3
Check
air

injection
pump
belt

tension
and
adjust
to

specifications
if

necessary

4

Plug
up
air

discharging
hose

from

C
A
C
valve
California
models

y

o

EC144A

Fig
EC
44

Plugging
C
A

C
Value

Air

Discharging
Hose

California
model

S

Disconnect
air

supply
hose
at

check
valve

6
Insert

open
pipe
end
of
Air

Pump

Test

Gauge
Adapter
STl9870000
in

air

supply
hose

Clamp
hose

securely

to

adapter
to

prevent
it
from

blowing

out
Position
adapter
and
test

gauge
so

that
air
blast
emitted

through
drilled

pipe
plug
will
be

harmlessly
dissipated

7
Install
a
tachometer
on

engine

With
the

specified
engine
speed
ob

serye
air

pressure
A

produced
at
test

gauge

Air

pressure
A

More
than

100

mmHg
3
94

inHg

at
2
600

rpm

I

jff

100
m

Hg

f1

3
94

mHg

I

EC145A

Fig
EC
45

Testing
Air

Pump

8
If
air

pressure
does
not
meet

above

specifications
proceed
as

follows
Emission

Control

System

Non

California
models

1
Repeat
2

and
3
above

2
With

engine
speed
at
1
500

rpm

disconnect
tube

from

adapter
and

close
hole
of

test

gauge
with

finger
If

a

leaking
sound
is
heard

or

leaking
air

is
felt

by
finger
at
relief
valve
relief

valve
is

malfunctioning
Relief
valve

should
be

replaced
or

repaired

3
If
air

injection
pump
does

not

meet
minimum

requirement
of

pres

sure
test
it
should
be

repaired

California
models

Disassemble
the
air

pump
and
re

pair
it

Check
valve

Warm

up
engine
thoroughiy

2
Disconnect

hose

leading
to

check

valve
from
air

hose
connector

3
Check
hose

opening
for

any
indi

cation
of
exhaust

gas
leaks
If
leaks

are

detected

replace
check
valve

4
Race

the

engine
lightly
at
about

2
000

rpm
and
then

return
it
to

idling
Visually
check
the
hose
for

any

indication
of
exhaust

gas
leaks

before

the

engine
returns
to

idling
speed
If

leaks
are
detected

replace
check
valve

EC146A

Fig
EC
46

Checking
Check
Valve

Air
pump
relief
valve

After

completing
inspection
of
air

pump
check
air

pump
relief

valve
in

the

following
steps

I
Disconnect
hoses

leading
to
check

valve
and
air
control
valve
from
air

hose

connector
and
install

blind
c

p

to
the
connector

2
With

engine
running
at
about

3
000

rpm
under

no
load

place
your

EG
7
hand
on
the
air
outlet
of
air

pump

relief
valve
to

check
for

discharged
air

If

no
air
is
felt

replace
the

air

pump

relief
valve

G

EC575

Fig
EC
47

Checking
Air

Pump

Relief
Valve

Anti
backfire
valve

A
B

valve

I
Warm

up
engine
thoroughly

2
Disconnect
hose
from
air

cleaner

and

place
a

finger
near
the

outlet

3
Run

engine
at
about
3

QOO
rpm

under
no

load
then

quickly
return
it

to

idling
If

you
feel
a

pull
or
suction

force
on

your
finger
the
anti
backfire

valve
is

functioning
normally
If

no

suction
is

felt

replace
the
anti
backfire

valve

EC768

Fig
EC
48

Chocking
Anti

backfire

Valve

C
A
C
valve

California
models

I

Make
sure
that

C
A
C

valve
vacu

um

hose
and
air

hose
are

not
cracked

2
Warm

up
engine
throughly

3
With

engine
at
idle

place
your

fmger
over

relief
hose

opening
to

check
for

presence
of
air

4

With

engine
idling
disconnect

vacuum
hose
at
C
A

C
valve

Then
make

sure
that
air
is

discharg

ed
from

C
A
C
valve

C

A
C
valve
is

functioning

properly

if
air
is

discharged
from
it

Note
When
tho
vaCUUm
hose

is
dis

connected

plug
it

up
or

engine
will

stumble

EC
47A

FiJ
Fig
EC
49

Disconnecting
Vacuum

Hose

from
C
A

C
Valve

5

Connect

hand
operated
vacuum

pump
in

place
and

manipulate
it
in

order

to

apply
a

pressure
of
2oo
to

250

mmHg
7
87

to
9
84

inHg

to

C
A
C

valve
Increase

engine
speed

to
3
000

rpm
and
confIrm
that

no
air

leaks
from
C

J
C
valve

Fig
EC

50

Checking
C
A
C

Valve

1

6
With
the
above

condition
discon

nect
air
hose
at
check
valve
and

plug
it

up
At
this

point
confirm

the
air

leaks

from

C
A

C
valve

ECl48A

Fig
EC

51

Checking
C
A
C
Volve
2
Emission

Control

System

7
If

teshesults

satisfy
3
4
5

and
6

the
C
A
C
valve

is

properly
function

ing

AIR
INDUCTION

SYSTEM
A
I
S

DESCRIPTION

The
air

induction

system
A
1
s
is

adopted
on
the
FU
model
and
Canada

models
and
is

designed
to
send
see

ondary
air
to
the

exhaust
tube
utiliz

ing
a
vacuum
caused

by
exhaust

pulsa

tion
in
the

exhaust
tube

Air
inductIon
valve

A
reed

valve

type
check
valve
is

installed
in

the
air

cleaner
When
the

exhaust

pressure
is
below

atmospheric

pressure

negative
pressure

secondary

air

is
sent
to
the
exhaust
manifold

When
the
exhaust

pressure
is

above

atmospheric
pressure
the

reed
valve

prevents

secondary
air

from

being
sent

back
to
the
air
cleaner

EC
t8
The

exhaust

pressure
in

the
exhaust

tube

usually
pulsates
in

response
to

the

opening
and

closing
of

the
exhaust

valve
and

it
decreases

below
atmos

pheric
pressure
periodically

If
a

secondary
air
intake
is

opened

to
the

atmosphere
under

vacuum
con

ditions

secondary
air

can
be

drawn

into

the
exhaust
tube
in

proportion
to

the
vacuum

Therefore
the
air
induction

system

A
I
s
reduces
CO

and
HC
emissions

in

exhaust

gases

operatiug
the
same
as

the
air

injection

system
A
I
s
The

system
cpnsistsof
an
air

in

tJctio

valve

a
filter
an

A
B
valve

and
hoses

fl

V

t

5

1

Air

ind9ction
valve

2
Air

c
eancr

3
Carburetor

4

Exhaust
manifold

5

Anti
obRcldlre
valve

EC919

Fig
EC
52

Ai
Induction

SYltem

1

Reed
valvo

2

Stopper

EC920

Fig
EC

53
Air
Induction

Val

Air
Induction
v
lve
filter

The
air
induction
valve
filter
is

installed
at
the
dust
side
of
the
air

cleaner
It

purifies
secondary
air

to
be

sent
to
the

exhaust
tube
The
fIlter

element
should
be

replaced
periodical

ly
in
accordance
with
the
Maintenance

Schedule

EC921

Fig
EC
54
Air
Induction
Valve

Filter

Antl
beckflre
v
lve
A
B
v
lve

Tltis
valve
is

controlled

by
intake

manifold
vacuum
to

prevent
backfire

in
the

exhaust
system
at
the
initial

period
of
deceleration

At
this

period
the
mixture
in

the

intake
manifold
becomes
too
rich
to

ignite
and
burn
in

the
combustion

chamber
and
burns

easily
in
the
ex

haust

system
with

injected
air
in
the

exhaust
manifold

The
anti

backfire
valve

provides
air

to
the
intake

manifold
to
make
the

air
fuel
mixture
leaner
and

prevents

backfire

If

the
valve
does
not
work

properly

unburned
ntixture
will
be

emitted

from

the
combustion
chambers
and

burns
with
the
aid
of

high
temperature

and

injected
air
which

causes
backfrre

To
intake

manifold

vacuum

To
intake

manifold

From
air

cleaner

EC069

Fig
EC
55
Anti

backfire
Value
Emission
Control

System

Air
Induction
Into
exhaust

port

The

secondary
air
fed
from
the
air

induction
valve

goes
through
the
check

valve
to
the
air

gallery
in

the

cylinder

head
It
is
then

distributed
to

each

exhaust

port
and

injected
near
the

exhaust
valve

I
Air

gallery

2
Exhaust

port

3
Exhaust
manifold

EC316

Fig
EC
56
Sectional
View

of

Exhaust
Port

REMOVAL
AND

INSTALLATION

Air
Induction
valve
and
filter

Remove
the
screws

securing
the

valve
and
filter
to
the
air

cleaner
body

The
air
induction
valve
and
valve
filter

can
then
be
taken

out

easily
Installa

tion
is
in
the
reverse

sequence
of

removal

EC922

Fig
EC
57

Removing
Air
Induction

Valve
and
Filter

EC
19
Air
Induction

pipe

Loosen
out
a

nut
securing
the

pipe

to

the

engine
cylinder
head
At
the

same
time
remove
the
screws

securing

the
bracket
and
rubber
hose

clamp

The
air
induction

pipe
can
then
be

taken
out
Installation
is
in
the
reverse

sequence
of
removal

Fig
EC
58

A
B
valve

The
A
B
valve
is
located
at
the

rear

side
of
the
air
cleaner
Remove

the
air

hoses
and
vacuum
tube

The
A
B
valve

can
then
be

taken

out
Installation
is
in
the

reverse
se

quence
of
removal

EC152A

Fig
EC
59

Removing
A
B
Valve

INSPECTION

Preliminary
Inspection

Check
hose
for
looseness

flatting

damage
or

faulty
connections
and

each

part
for

proper
installation
If

necessary

replace

Air
Induction
valve
and
filter

I
Disconnect
air
induction
hose
at

air
induction

pipe
side
Suck
or
blow

hose
to
make
sure
that
air

flows

only

on
the
air

induction

pipe
side