1977 DATSUN PICK-UP engine

Minimizes
exhaust

gas
tempera

lure
rise

2
Minimizes

horsepower
losses
re

suiting
from
air

injection
into
the

exhaust

system

3
Protects

pump
from
excessive

back

pressure

The
air

pump
relief
valve
is
installed

as
shown
in

Figure
EC

20

The

secondary
air
is

discharged

from
the
air

pump
relief
valve

to
the

dust
side
of
the
carburetor
air
cleaner

To
carburetor

air
cleaner

Secondary

air

To
carburetor

air

cleaner

J
erCOndary

r

r

EC294

Fig
EC
20
Air

pump
relief
valve
Emission
Control

System

Emargency
air
retial
valve

E
A
R
Valve

California
models

The

emergency
air
relief
valve
con

trols
the

quantity
of
secondary
air

fed

from
the
air

pump
according
to

load

condition
and
it

discharges
the
see

ondary
air
into
the

atmosphere
to

prevent
overheating
of
the

catalytic

converter

The

emergency
air
relief
valve
con

sists
of
a

diaphragm
a

spring
and

a

valve
which
is

coupled
to

diaphragm

1

Diaphragm

2

Val

3

Spring

4

Diaphragm
chamber

EC536

Fig
EC

21

mergency
air

relief
valve

OPERATION

As
mentioned

previously
there

are

two

types
of
Air

Injection
Systems

A
I

S
a

non
California

type
and
a
California

type
The
California
stand

ard

type
includes
a

system
which

controls

injection
of

secondary
air

so

as
to
assure

proper
function
of
the

catalytic
converter
and
a

system

which
controls
the

supply
of
second

ary
air
to

prevent
abnormal

tempera

tUfe
rise
in
the

catalytic
converter

The
A
I
S
consists
of
the

following

systems

L
A

system
which
allows

injection

of

secondary
air
into
the
exhaust

port

2
A

system
which

bypasses
sec

ondary
air

from
the
air

pump
relief

valve

to
the

carburetor
air

cleaner

during

high
speed
engine
operation

3
A

system
which

supplies
air

from

the
carburetor
air
cleaner

to
the
intake

manifold

by
means
of
the
anti

backfire

valve
so
as
to

prevent
after
fire

during

deceleration

4
A

system
which

controls

injection

of
the

secondary
air

by
means
of
the

air

control
valve

so
as
to
maintain
the

catalytic
converter
at
an

optimum

temperature
level
under

lightly
loaded

condi
tions

Califomia

type
only

5
A

system
which
controls
the

sup

ply
of

secondary
air

through
the
emer

gency
air

relief
vilve

io
pfevent
ab

normal

temperature
rise
of
the

cataly

tic

converter

California

type
only

A
I

S

operation
is

as
follows

I

I

t

1
r

9

I
Air

pump
6

Check
valve

I
0
L
2
Air

pump
air
deaner
7
Air

gallery
pipe

3
Air

relief
valve
8
Injection
non
e

r
4
Air
cleaner
9

Exhaust
manifold

5

Carburetor
10

Anti
backflIe
valve

EC179

Fig
EC
22
Non

California
type
A
I
S

EC
12

9
From
air

pump

l

h
1

Not
actuated

REMOVAL
AND

INSTALLATION

Air
p
mp
sir
cleaner

Remove
air
hose

then
detach
air

cleaner

from

hoodledge
Air
cleaner

element
and
Ii
r
deancr
lower

body
are

built
into
a
unit
construction

Replace

air
cleaner
clcl

nen
and

lower

body
as

an

assembly

J

J

tt
c

t
o

J

EC
323

Fig
EC
26
Replacing
oir
cleaner

element

Air

pum

Remove
air
hoses

from
air

pump

2
Loosen
air

pump
adjusting
bar

mounting
bolts
and
air

pump
mount

ing
bolts
then

remove
air

pump
drive

bell

3
Remove
air

pump
pulley

4
Remove
air

pump
from
bracket

Air
control
valve

California
models

l
Disconnect

air
hoses
and
a
vacu

um
hose
from
air
control
valve

2
Remove
air
con
trol
valve
from

bracket

E
A

R
valve
California
modela

Remove
vacuum

pipe
and
air

hose

and
dismount
E

A
R
valve
Emission
Control

System

o

jJ
To

Intake
mamfold

rF
vacuum

r

To
air

cleaner

From
air

pump

EC781

Fig
EC
27
Locotion

of
E
A
R
wive

Antl
backflravalve

Disconnect
air
hose
and
vacuum

hose
from
anti
backfire
valve

Check
valve

Disconnect
hose
and
remove
check

valve
from
air

gallery
pipe

Air

ganery
pIpe
andinJactlon

nozzles

It
is

very
difficult
to
remove
the
air

gallery
from
the
exhaust
manifold

without

bending
the

pipe
which
could

result
in
fractures
or

leakage
There

fore

removal
of

the
air

gallery
pipe

and

injection
nozzles
should
be
under

taken

only
when

they
are

damaged

I
Lubricate
around
the

connecting

portion
of
air

injection
nozzle
and
air

gallery
with

engine
oil

2
Hold
air

injection
nozzle

hexagon

head
with
a

wrench
and
unfasten
flare

screw

connecting
ait

gallery
to

injec

tion
nozzle
Remove
air

gallery

EC
14
To
intake

manifold

vaCUl
lm

r

Y

4
9
Gf

T

I
To

air
cleaner

I

Actuated

EC299

Fig
EC
25

Operation
of
air
control
value

Notes

a

Apply
engine
011
to
rews
several

times
during
above

work

b
Be
atreful
not
to

damage
other

parts

3
Unfasten
air

injection
nozzle

from

cylinder
head

applying
engine
oil

to
screwed

portion
several
times

4

Check
air

gallery
and
nozzle
for

fractures
or
leakage
Clean
air

injection

nozzle
with
a
wire
brush

5

At
time
of
installation
hold
air

injection
nozzle

hexagon
head
with

a

wrench
and

tighten
air

gallery
flange

screw
to
a

torque
of
5
0
to
5
9

kg
m

36
to
43
ft
lb

6
Check

cylinder
head
air

injection

nozzle
and
air

gallery
for
leaks
with

engine
running

Air

pump
relief
vslve

Loosen
carburetor
air
cleaner

mounting
sc
ews
and

remove
air

pump
relief
valve

InstallatIon

Install
in
the

reverse
order
of
reo

moval

DISASSEMBLY
AND

ASSEMBLY

Disassembly
of
air
pump

1
Remove
four

pulley
drive
bolts

and
remove

pulley
from
hub

2

Secure
air

pump
drive
hub
in

a

vise

as
shewn
in

Figure
EC

28
and

remove
four
end
cover
bolts

Air

pump

I

Operate
engine
until
it
reaches

normal

operating
temperature

2

Inspect
all
hose
hose
connec

tions
and
air

gallery
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

Disconnect
air
supply
hose
at

check
valve

5

Disconnect
vacuum
hose
from
the

air

control
valve
California

type

only

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

lli
uge
so

that
air
blast
emitted

through
drilled

pipe
plug
will
be

harmlessly

dissipated

7
Install

a
tachometer

on

engine

With

engine
speed
at
2

600

rpm
ob

serve

pressure
produced
at

test

gauge

Air

pressure
should
be
100

mmHg

3

94

inHg
or
more

8
If
air

pressure
does

not
meet

above

specifications
proceed
as
fol

lows

I

Repeat
2
and
3

above

2
Disconnect
air

supply
hose
at

anti
backfire
valve

Plug
air

hose

open

ing
and

screw
with
a

clamp
Repeat

pressure
test

3
With

engine

speed
at
1

500

rpm

close
hole
of
test

gauge
with

finger
If

a

leaking
sound

is
heard
or

leaking
air

is
felt

by
ftnger
at
relief

valve
relief

valve
is

malfunctioning
Relief
valve

should

be

replaced
or

repaired

4

If
air

injection
pump
does
not

meet
minimum

requirement
of

pres

sure
test
it

should
be

replaced

Control
valve

The

following
procedures
are
reo

commended
for

checking
and
or
as

certaining
that
the
various

components

of
the
exhaust
emission
con
Irol

system

are

operating

properly

The

engine
and
all

components

must

be
at
normal

operating
tempera

tures
when
the

tests
are

performed

Prior

to

performing
any
extensive

diag

nosis

of
the
exhaust
control

system
it
Emission
Control

System

must
be
determined
that

the

engine
as

a
unit
is

functioning
properly

Check
valva

Warm

up
engine
thoroughly

2

Disconnect
hose

leading
to
check

valve
from
air

hose
COJUlector

3

Check
hose

opening
for

any
indi

cation
of
exhaust

gas
leaks
Ifleaks
are

detected

replace
check
valve

4

Race
the

engine

lightly
at
about

2
000

cpm
and
then

return
it
to

idling
VisuaDy
check
the
hose
for

any

indication
of
exhaust

gas
leaks
before

the

engine
returns
to

idling

speed
If

leaks
are
detected

replace
check
valve

EC310

Fig
EC
43

Checking
check
valve

Air

pump
raIle
valve

After

completing
inspection
of
air

pump
check
air

pump
relief
valve
in

the

following
steps

J

Disconnect
hoses

leading
to
check

valve
and
air
control

valve
from
air

hose

connector
and

install
blind

cap

to
the

connector

2
With

engine
running
at

about

3
000

rpm
under
no
load

place
your

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

EC311

Fig
EC
44

Checking
air

pump
relief

valve

EC

18
Air
control
valve

C
U
ornla
models

I
Warm

up
engine
thoroughly

2
Before

checking
air
control

valve

check
all
hoses

for
loose
connection

leaks
etc
and

repair
or

correct
if

necessary

3

With

engine
idling
disconnect
the

outlet
side
hose
of

the
air
control

valve
and

place

your
hand
on
the
air

hose
outlet
to
check
for
air
If
no
air
is

felt

replace
the
air

control
valve

4

Pull
vacuum
hose
off
from
air

con
trol
valve
If

discharge
of
air
from

air
hose

stops
the
air
con
trol
valve

is

normaL
If

discharge
is
still
felt

replace

the
valve

Plug
up
the

removed

vacuum
hose

to

stabilize

engine
running

EC312

Fig
EC
45

Checking
air
control
valve

Emarsancy
air
rella
valve

E
A
R
Valve

lCalHornla
models

L
Warm

up
engine
thoroughly

2

Before

checking
air

control
valve

check
all
hoses
for
loose
connection

leaks
etc
and

repair
or
correct
if

necessary

3
Race

engine
approximately

2
000

rpm
under
no
load
Place

your

hand
on
air

outlet
of
E

A
R
valve
to

check
for

presence
of

discharged
air
If

no
air

is
felt

E
A

R
valve
is
normal

4

Disconnect
vacuum
hose
from

B
A

R
valve
as
shown
in

Figure
EC

46

Race

engine
approximately
2
000

rpm
under
no
load
Place

your
hand

on
air
outlet
of
E
A
R
valve
to
check

for

presence
of

discharged
air
If
air
is

felt

E
A
R
valve
is
normaL

5

If
E
A
R

valve
does
not
function

properly
at
above

steps

replace
E
A
R

valve

To

air

pump

I

ET267

Fig
EC
46

Cheeking
E
A
R
volve

Anti
backfire

valve
A
valve

Warm

up
engine

thoroughly

2
Disconnect
hose

from
air

cleaner

and

place
a

finger
near
the
outlet

3
Run

engine
at
about
3

000

rpin

under
no
load
then

quickly
cetum
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
backflre

valve

Fig
EC
47
Checking
anti

backfire
valve
1
t
D

I
Y1

VI
I

ID
4

JO
0

2
E

C
R
control
valve

3

E
C
R

passage

4
Intake
manifold

5

Thermal
vacuum
valve

6
E
C
R
tube

7
Exhaust

manifold
Emission
Control

System

tXHAUST
GAS

RECIRCULATION

CONTROL
SYSTEM

E

G
R

DESCRIPTION

In
the

exhaust

gas
recirculation

system
a

part
of
the
exhaust

gas
is

returned
to
the

combustion
chamber

to
lower
the

spark
flame

temperature

during
combustion
This
results
in
a

reduction

of
the

nitrogen
oxide

con

ten
t

in
the
exhaust

gas

The
exhaust

gas
recirculation

sys

tem
consists

of
an
E
G
R

passage

E
G
R

con
trol
valve
thermal

vacuum

volve
E
G
R

tube
and
hose
A

warn

@
I
ing
system
which
indicates
when
the

E
G
R

control

system
must
be

in

spected
is
also
installed
in

all
620

models

except
those
bound
for

Coli

fornia
and
Canada

When
the
E

G
R
con
trol

valve
is

open
some
of

the
exhaust

gas
is

led

from
the

exhaust
manifold
to
the

E
G

R
chamber

through
the
E
G

R

passage
The
exhaust

gas
is

then
con

trolled
in

quantity
by
the
E
G
R

valve

and
is
introduced
into
the

intake

manifold

Open
c1ose

operation
of
the
E
G
R

control
valve

is
controlled

by
the

thermal

vacuum
valve
which

opera
tes

on

carburetor
vacuum
and

engine
cool

ant

temperature

EC349

Fig
EC
4
Exhaust
Gas
Recirculation

system
E
G
R

E
G
R

system
operating
Thermal
Intake
manifold
E
G
R

Remarks

E
G
R

water

temperature
oC
OF
vacuum
valve
vacuum
control
valve

Below
570C
135OF
Close
Close

Non
california

Above

MfT
models

only
Idling

Not
Above
57

to
630C

Open
70

mmHg
Close

actuated
135
to
145OF
76

inHg

California
models

Below

and
N
on
Fullthrollle

f

alifomia

AfT

Above
57
to
6
oC
models

Actua
ted

Open
Above
50

mmHg

Open

135
to
145OF
1
97

inHg

EC
19
OPERATION

Operation
of
E
G
R

system
is
as

shown
below

E
G
R
OFF

operation

When

engine
coolant

temperature

is
low

recirculated
exhaust

gas
causes

irregular
engine

operation
To

prevent
Emission
Control

System

this
recirculation

of
exhaust

gas
must

be
cut
off

for
a
few

minutes
after

engine
has
started
The
thermal
vacu

um
valve

is

provided
for
this

purpose

r
rn

11

L

e

7

E
G
R

controlval
le
clo

2

When

engine
coolant

temperature

is
above

the

working

temperature
of

the
thermal

vacuum
valve

I
The
valve

port
come

to
the

top

J
It
remains

closed
while

engine
coolant

temperature
is
low
and

keeps
the

E
G
R
control
valve
closed

thereby

culling
off
the

E
G
R
circuit

I

lW
jS

1
Throttle
valve

Thermal
vacuum

valve
close

j
Note

m
Vacuum
condition

of
the

throttle
valve
du

ring

engine

idling
for

improved
idling

operation

At

this

point
vacuum
does
not

actuate

the
E
G
R
control
valve

r
T
D

L

t

i

q

II

E
G
R
control

valve

close

2
In
the
full

throttle

driving
posi

tion

the
suction
vacuum

on
the
vacu
JllrI

Thermal
vacuum
valve

ope

um

passage
does

not

surpass
the
vacu

um

required
to

actuate
the
E
G
R

EC
20
EC227

Fig
EC
49
E
G
R
not

actuated

though
intake

manifold

vacuum
is

high
and
E
G
R

control
valve
remain

closed

l

Throttle
valve

EC228

Fig
EC
50

E
G
R
nol

actualed

control

valve

6

Thermal
vacuum
valve

Open

E
G
R
control
valve
Close

E
G
R
ON

operation

The
E
G
R
circuit
is

completed

only
when

engine
coolant

temperature
Emission
Control

System

I

I
Note
Vacuum
condition

EC793

Fig
EC
51
E
G
R
not
actuated

is
above
the

working
temperature
of

the

thermal
vacuum
valve
and
carbu
retor
suction
vacuum
is

large
enough

to

open
the
E
G
R

control
valve

Y
m
l

fj

t1f
1t
3
0

l

P
@
0
f
Y
f

1
i0
W
g

1
i3
iiA
d

m

E
N
ti

n
k

i

l
i
Throttle
valve

n

L
r

E

G
R

control
valve

Open

E
G
R
control
valva

The

E
G
R

control
valve
controls

the

quantity
of
exhaust

gas
to
be
led

to
the

intake
manifold

through
vertical

movement
of
the

taper
valve
connect

ed

to
the

diaphragm
to
which

vacuum
Thermal
vacuum

valve

Open

Note

iiiI
Vacuum
condition

EC794

Fig
EC
52
E
G
R
actuated

is

applied
in

response
to
the

opening

of
the
carburetor
throttle
valve
The

E
G
R
control
valve
is
installed
on
the

E
G
R

passage
through
a

gasket

E
G
R
con
trol
valve
construction

and

type
vary
with

transmission

type
and

car
destination
For
identification

purposes
the

part
number
is

stamped

on
the
recessed

portion
at
the

top
of

the
valve

The

construction
of
the
E
G
R

control
valve
is

shown
below

EC
21

j

EC231

Thermal

vacuum
valva
o

o

m
Emission

Control

System

0

o

o

o

l

l
@

The
thermal
vacuum
valve

is

mounted
in

the

engine
thermostat

housing
It

detects

engine
coolan
t

tem

perature
by
means
of
a

built
in

bi

metal
and

opensor
closes
the

vacuum

passage
in
the

thermal
vacuum

valve

mt

li

t

00
t

EC232

Fig
EC
54
Thennal

vacuum
valve
To
E

G
R
control
valve

From
carburetor

1

Spring

2
Bi
metal

3

O

ring

E
G
R

warning

system

The

E
G
R

warning
system
install
1

Diaphragm
spring

2

Diaphragm

3
Valve
shaft

4

Valve

5
Valve

Seat

6
Valve
cham
ber

Fig
EC
53
E
G

R
control
value

When
the

vacuum

passage
is

open
the

carburetor
suction

vacuum
is

applied

to
the

diaphragm
of
the
E
G
R

con

trol
valve
to

actuate
the

taper
valve

connected
to
the

diaphragm

theconsiiiictlo

nlie
thermal

vacuum
valve
is

shown
below

ed

independently
of
the

E
G
R

con

trol

system
monitors

the
distance
the

car
has
travelled
and

indicates
when

EC
22
the
E

G
R

control

system
must
be

checked

The
E
G
R

warning
system
consists

of

an
odometer
switch

detector
drive

counter
E

G
R

warning

lamp
and

harnesses

When
the

earn
in
the

odom

eter
switch
connected
to

the

speed

ometer
turns

once
for

each
OAkm
4

mile
the

contact

point
of
the
elec

trica
circuit
closes

allowing
electric

current
to
flow

through
the

magnet

coil
of

the
detector

drive
counter

Thus

energized
the

magnet
coil
ac

Wates

the
latchet
to

turn
the
c
unter

wheel

by
one

pitch
When
the

number

of

counts
reaches
50
000
the
latchet

drops
in

a

groove
provided
on
the

periphery
of

the
counter
wheel
to

activate

the
detector

drive
counter

switch

Then
the

E
G
R

warning

lamp

comes
on

indicating
that
the
E
G
R

control

system
Should
be
checked

The

detector
drive

coun
teT
is

equip

ped
with
an
odometer
which

can
tell

when
to
service

the
E

G
R
contr0
I

system

After

completing

periodic
check

reset
the
odometer
to

zero
by
hand

proceeding
as
follows

1
Remove

grommet
installed
on

the
side

surface
of

detector
drive

counter
unit

2
insert

a
bar

or
a
screwdriver

tip

into
the

hole
from

which

grommet
has

been

removed
and

press
down
knob

provided
in

the
detector
drive
counter

for

resetting

The
E

G
R

warning

lamp
comes

on

under
the

following
circumstances

1
When
the
number
of

counts
has

reached
50
000
In
this

case
the

lamp

indicates
that
E

G
R

control

system

must
be
checked

2
When

operating
starter
motor

Notes

a
It
is

an
indication
of

problem
in

the

E

G
R

warning
lamp
or

problems

in
the

point
or
in
the
harnesses
if

the

lamp
does
not

light
at

50
000

counts

b

The
E

G
R

warning
system
is

mounted

on
all
620
models

except

those

bound
for
California
and

Canada

1

1

I
I

I

1
v

v

I
I

I
I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

L
0

I

Magnet
coil

Detector
drive

counter

REMOVAL
AND

INSTALLATION

Remove
air
cleaner

before

removing

E
G
R
control

system
For
removal

and

installation
of
air

cleaner
refer
to

Air
Cleaner
section

Page
EF
S

Removal

I
E
G
R
control
valve

After

removing
the

following
parts

the
E

G
R

controi
valve
can

be
dis

mounted

Vacuum

hose
thermal
vacuum

valve
to
E
G
R

control
valve

E
G
R
control
valve

mounting
nut

Note
To
remove

vacuum
hose
flat

ten

clip
connecting
vacuum
hose
to

E
G
R
control
valve
and

pull
the

hose
off
with
hand
Emission
Control

System

Ignition
switch

E
G
R

warning
lamp

f

1
Ignition
switch

start

position

Fuse

1
A
Odometer
switch

r

I
I

I

I
v

I

I
I

i

lQ
U

1

mi

L
J

EC233

Fig
EC
55
E
G
R

warning
circuit

EC234

Fig
EC
56

Removing
KG
R
control

valve

2
E
G
R

pass
ge

After

removing
the

following

parts

the
E
G
R

passage
can
be
dismounted

Exhaust
gas
return

tube
exhaust

manifold

to
E
G
R

passage

B1ow

by
hose

cylinder
block

to

P
C
v
valve

Vacuum
hose
AB
valve
to
E
G
R

passage

E
G
R

passage
mounting
bolt

EC

23
EC541

Fig
EC
57

Removing
E
G
R

passage

3

Thermal
vacuum

valve

After

removing
the

following

parts

the
thermal
vacuum
valve
can
be
dis

mounted

Vacuum
hose

carburetor
to
ther

mal
vacuum
valve

Vacuum
hose
thermal
vacuum

valve

to
E

G
R
control
valve

Note
Drain

engine
coolant
before

dis

mounting
thermal
vacu
m
valve

Fig
EC
58

Removing
thermal

vacu
um
valve