check engine DATSUN 510 1968 Service Owner's Manual

54

CHAP1ER
SIX

2
Set
the
valve

spnng
seat

m

position
on
the

top
of
the
block
and

over
the

valve
stem

3
Place
the
oil
seal
over
the

valve
stem

4
Place
the

mner
and

outer
valve

spnngs
over

the
valve
stem

S

Place
the

spnng
retamer

over
the

springs

compress
spnngs
With

spring
compressor
Figure

55
and
mstall
valve
collets
around
valve
stem

so
that

they
lock
onto
stem

6
Release

spnng
compressor
If
collets
are
firm

ly
locked
onto
the

groove
m
the

valve
stem

assembly
IS

complete

7
Install
the
rocker

guIde
on

top
of
the

valve

stem
when

assemblmg
the
rocker

pivot
assembly

VaIve
Rocker
Pivot

Assembly

1
Thread
lock
nut
onto
valve
rocker

pivOt
and

place
rocker
retaIner
over
the
valve
rocker

pivOt

2
Thread
the
above

assembly
mto
the
rocker

bushIng
protrudIng
from
the

head

Camshaft

Assembly

1
Mount
the

locatIng
plate
on
the
front
of
the

head
as

shown
m

FJgIlI
1
56

2
From
the
back
of
the
head

carefully
InSert

the
camshaft

through
the

four
camshaft

beanngs

being
ca
efu1
not
to
move
or

damage
the
bear

ings

NOTE
Install
the

CQJ7IShaft

sprocket

onto
the

camshaft
so
that

the
three

locating
holes
are

at
the

top
left
and

bottom
h

1
3

Install
the

camshaft

sprocket
and
fuel

pump

cam
onto

the
front
of
the

camshaft
and

torque

to

specificatIon

4
Check
the
camshaft
for
end

play
using
a

feeler

gauge
as

preViously
described

Rocker
Pivot

Assembly

1
Push
down
on
valve

spnng
with
screwdriver

and
insert
rocker

piVOt
arm
between
camshaft

and
valve
stem

Insert
rocker
valve

guide
onto

top
of

valve
stem

at
this
time

2
Install
valve

rocker

springs
over

top
of
rocker

pivot
arm

Piston
and

Connecting
Rod

Assembly

1

Assemble
the
four

pistons

pms
and
connect

mg
rods
Secure

piston

pm
The

connecting
rod

IS

press
fitted
onto
the

pISton
pin
With
from
1
to

3
tons
of
force

NOTE
The

pistons
are

marked
with

an
F
which

should

point
toward
the

front
of
the

engine
The

connecting

rods

must
be
installed
so

that
the
011

Jet
In
the

large
end

IS

positioned
to

ward
the

right
Side

of
the

tnglne
The

center

of
the

piston
pin
IS

oD
set
In

relation
to
the

center

of
the

piston
so

correct

assembly
is
cntical

2
Use
a

nng
expander
to
install
the

rings
onto

the

pistons
Install
the

top
and
rmddle

nngs

with
the
marks

up

3

Lubncate
the

rod

bearings
hghtly
and
mstall

them
into

their

respective

connectIng
rods
and

rod

caps

ENGINE
55

Cylinder
Block

Assembly

1
PositIon
all
crankshaft

parts
on
a
work
bench

ThIS
mcludes
the
crankshaft
main

beanngs

rear
011

seal
woodruff

keys
crankshaft

gear

011

pump
gear
011
thrower
bolts
and

bearing

caps
Figure
57
shows
the

arrangement

@

2
Insert
maIO

beanngs
mto

appropnate
cy1m

der
block
holders

NOTE
The
center
No
3

beanng
IS

the

only
flanged
type
of
thrust
bear

Ing
Bearings
No
2
and
No
4
are

Identical
No
1
and
No
5

Jaring
ap

pear
identical
but
No
1
as
an
011

hole
All

bearings
except
No
1
are

Interchangeable
as
to

upper
and
lower

half

3

LIghtly
lubncate
the

crankshaft
and

beanng

matmg
surfaces
then
mstall

beanngs
10
mam

beanng
caps

4
Install
the
crankshaft

5
Install
mam

beanng
caps
over

crankshaft

msert
mam

cap
bolts
and

tighten
hghtly
The

mam

beanng
caps
have
an
arrow
marked
on

each
one
These
must

pomt
to
the
front
of
the

engme

6

Gently
move
the
crankshaft
10
an
aXIal
drrec

don

toward
the
front
of
the

engme
to

venfy
that

the
mam

beanng
caps
are

properly
alIgned
and

seated
7
Use
a

torque
wrench
to

tighten
the

cap
bolts

to
the
hmlts

speCIfied
The

t1ghtenmg
operatIon

should
be
done

gradually
10
three

or
four

sep

arate

stages
starting
10
the
center
and

workmg

outward

to
each
end

8
Rotate
the
crankshaft
to
make
certain
it
isn
t

bmding

9
Use
a
feeler

gauge
to
check
the
end

play
at

the
center

No
3

beanng
Figure
58

10
Install
the
SIde
oll
seals
into
the
rear
mam

cap
and

cy1mder
block
as
shown
10

Figure
59

@

11
Install
the
rear
011
seal
WIth
Datsun
tool

ST49370000
or

equIvalent

12
Install
the
rear
end

plate

13
Install
the

flywheel
WIth

proper
bolts
and

lock
washers
and

torque
as

specified

56

CHAPTER
SIX

NOTE
Lubncate
the

cylinder
walls

with
new

engine
oil

prior
to
insertIOn

of
pistOns
Make

certain
that
the

ring

gaps
are
not
In
line

wIth
one
another

Place

the

gaps
180

degrees
from
each

other

and
not

posltloned
either

front

to
back
or

dIrectly
in
line
with

the

piston
pIns

CAUTION

Use
extreme
care
when

Inserting
pzs

tons
so
as
to
avoId

crankshaft

damage

14
With
the
aid
of

a

nng
compressor
illStaIl

the

pISton
and

connectmg
rod
assembhes
into

the

cyhnder
block

as
shown
in

Figure
60
Make

certain
the

proper
piston
IS
mserted
mto
the

proper
hner
and
the
F
on
each

pISton
faces

forward

@

15
Install

beanngs
mto
the

connectIng
rod

caps

after

lubncatmg
them

hghtly

16

Gently
push
connecting
rods
With

beanngs

installed
down
the

cyhnder
until
contact

IS
made

with
the
crankshaft

17
Set

connectIng
rod

caps
over
crankshaft
and

insert

COnnectIng
rod
bolts
Make
certam
that
the

numbers
on
the
rods

and
the
rod

caps
face
in

the
same
direction

18

Tighten
rod
bolts
to
the

proper
torque
speci

ficatIon

as
shown

m

Figure
61

I
J

@v

N

i

19
Check
the

connecting
rod
end

play
With
a

feeler

gauge
as

previously
described

Cylinder
Head
Installation

1

Spread
a
suitable

gasket
seahng
agent
on
the

top
of
the

cylinder
block
and

position
a
new
head

gasket

2

Spread
seahng
agent
on

top
of
the

gasket

CAUTION

PositIon
the

crankshaft
so
that
no

pzston
IS
at

top
dead
center

Before

installing
head

point
the

keys
on
the

camshaft
and

crankshaft

straight
up

Once

the
head
zs

Installed
do
not

rotate
the

camshaft
and

crankshaft

separately
as

damage
to
the

piston

tops
might
result

3
Place
the

cyhnder
gently
onto
the
head

gask
et

NOTE
Three

dIfferent

types
of
bolts

are
used

to
hold
down
the
head

Make

certain
the

proper
ones
are
used

In

the

proper
places

4
Insert
head
bolts

through
holes
ill
head
and

thread
them
mto
the

cyhnder
block

5

Refemng
to

Figure
62

use
a

torque
wrench

and
Datsun
tool
ST49010000
or

equivalent
to

tIghten
the
head
bolts
to

specIficatIon
Tighten

them

gradually
m
three
or
four

stages
wlnle
fol

lOWIng
the

sequence
diagram
Torque
values
are

hsted

m
the

specIfication
table

FUEL
SYSTEM
71

Dash
Pot

Adjustment

The

adjustment
of
the
dash

pot
IS
done

by

warmmg
up
the

engme
properly
and

checkIng
If

the
throttle
lever
touches
th
dash

pot
stem
as

the

engine
reaches
1
800
and
2
000

rpm
under

no
load
conditIons

Proper
contact
between
the

throttle
lever
and
the
dash

pot
stem

produces
a

normal
dash

pot
performance
Should
a
normal

mcrease
m

engme
speed
not
occur

adjust
the

dash

pot
as
follows

1
Loosen
the
dash

pot
locknuts

2
Rotate
the
dash

pot
nght
and
then
left

3

Adjust
the
dash

pot
so
that
the
throttle
lever

hIts
the
stem
between
1
800
and
2
000

rpm

4
Fasten
the
lock
nuts

securely

5
The
clearance
between
the
throttle
valve
and

the
throttle
chamber
wall
should
be
0
0709
m

0
8mm

or
10

degrees
In
throttle
valve

angle

MAJOR
CARBURETOR

SERVICE
PROCEDURES

A
carburetor
m

good
operatIng
condition
will

delIver
the

pr
per
gasolme
and
aIr
ratIos
for
all

engme
runnmg
speeds
A

gradual
declme
In

smoothness

response
and

power
Will
occur
as

the
carburetor

slIps
from

adjustment
and
Its
delI

cate

parts
become

dirty
and
worn
Overhaul

should

only
be

attempted
by
an

expenenced

mechanic

Accurate
calIbratIon
of

passages
and
dIS

charge
hole

reqUIre
that

extreme
care
be
taken

In

dISassembly
cleanmg
and

reassembly
Use

only
a

hIgh
grade
carburetor
cleaner
and
com

pressed
arr
to
clean

parts
and

passages
Never

use
wire
or
other

pOInted
Instruments
for
clean

ing
CalIbratIon
of
the
carburetor
will
be
af

fected
The

procedures
below
are

generally
true

for
all
models
As
an
aId

Figures
13
and
14
are

typIcal
examples
of
the
carburetors
used

Carburetor
Removal

1
Remove
the
au
cleaner

by
dIsconnectIng
all

hoses
attached
to
It

remoVmg
the
two
bolts

holdmg
the

aIr
cleaner
to
the

support
and

loos

enmg
the
band
bolt
at
the
base
of
the
aIr
cleaner

2
DIsconnect
fuellme
vacuum
Ime
and
choke

wire
u

eqUIpped
from
the
carburetor
3
Remove
the
throttle
lever

4
Remove
four
nuts
and
washers

holdmg
car

buretor
to
manIfold

5
Lift
carburetor
off
of
manuold

6
Remove
and
dIscard
carburetor
to
manuold

gasket

7
Place
carburetor
on
clean
workbench

Carburetor

Disassembly

1
The
maIn

Jets
slow

Jets
and
needle
valves
on

both
the

pnmary
and

secondary
systenIS
are

accessIble
from
outsIde
the
carburetor
Refer
to

FIgures
13
and
14
for
locatI
n

2
The
choke
chamber
can
be
detached

by
re

mOVIng
the

connectIng
rod

pump
connectIng

rod
return

sprmg
stop
pm
and
the

set
screws

I

that
hold

It
in

place

3
The

pnmary
and

secondary
emulSIon
tubes

can
be
disassembled

by
remOVIng
the
mam
air

bleeds

on
the

respectIve
SIdes

4

To
check
the
accelerator

pump
remove
the

cylInder
cover
Be
careful
not
to
lose
the

return

spnng
and
Inlet
valve
at
the
lower

part
of
the

pIston
durmg
dIsassembly

5
Detach
the
throttle
chamber
from
the
float

chamber

by
remOVIng
the
rod

lInkIng
the
dia

phragm
WIth
the

secondary
throttle
valve
and

the
four
screws
that
hold
It
However
It
IS

preferable
to
leave
the
throttle
valve
mtact
unless

absolutely
reqUired
If

It
IS

necessary
to
dlS

assemble
the
valve
It
should
be
Installed
so
that

the

secondary
throttle
valve
will
be

gap
free

OtherwIse
stable
Idle
and

good
slow

speed

performance
will
suffer

is
To
check
the
float
the
float
chamber
cover

must
be
removed

I

7
The

dIaphragm
IS
dIsassembled

by
removing

the
set
screws

holdmg
the

dIaphragm
chamber

cover
In

reassemblIng
the

diaphragm
be
careful

not
to
turn
the

edge
of
the

dIaphragm
up

8
In

dlsassemblmg
and

reassembling
the
mter

lockIng
lInks
take
care
so
that
each

lInkage
has

a
smooth
actIon
and
that

parts
are
not
forced

mto

pOSItIon

9
For
vehIcles

equipped
With
an
automatIc

choke
remove
the
brmetal

case

by
releasmg
the

set
screws
The
bimetal

1l
extremely
senSItIve

COOLING
SYSTEM
89

FAN
CLUTCH

Fan
Clutch

Operation
and

Inspection

Figure
6
shows
a

typICal
fan
clutch
dISas

sembled
Check
the
umt
whenever
the
water

pump
IS
removed
or
whenever
troubles
are

suspected
m
the

assembly
OperatIon
of
the
fan

clutch
should

be
observed
when
the
vehIcle
is

at

nmning

temperature

Operation
plate
Dust
cover
Drum

o9
Q

SpIder
assembly
LIning

CD

1
Warm

up
the

engme

2
MaIntam

engIne
speed
at
2
500

rpm

3

Usmg
a
thermometer
measure
the

temper

ature
close
to
the
fan
clutch

assembly
on
the

fan

4
The
clutch
should

engage
when
the

temp

erature
reaches
17

degrees
F
65

degrees
C

Conversely
the
clutch
should

deenergIze
when

the

temperature
drops
to
97

degrees
F
54
de

grees
C

5
Take
the
measurements
at
least
twice
SInce

the
thermostat
has
somewhat
of
a
tlme

lag

6
If
the
fan
clutch
falls
to

operate
properly
It

should
be
dIsassembled
and
servIced

Fan
Clutch

Disassembly

1
Follow
the
mstructIons
as

prevIOusly
gIven
to

remove
the
fan
and
clutch

assembly
from
the

water

pump

2
Refer
to
the

appropnate
exploded
illustratIon

for

your
model
and

to

Figure
7
which
shows
a

typiCal
fan
clutch

assembly

3
DIsassemble
unit
and

mspect
all

parts
for

signs
of
wear
or

breakage

4
To
check
the

operatIon
of
the
fan
clutch

thermostat

submerge
the

operatIon

plate
With

the
thermostat
In
hot
water
of
126

degrees
F

70

degrees
C
for
two
to
three
mmutes

Replace

if

It
faIls
to

operate

5
Assemble
the

fan
clutch
m
the
reverse
order

o

dIsassembly
THERMOSTAT

The

system
thermostat
IS
located
inside
the

water
outlet
elbow
on
the

upper
left
hand

por

bon
of
the

cylInder
head
The

temperature
sens

Ing
deVice

IS
threaded
Into
the
base
of
the
therm

ostat

housmg
and
IS
connected

electrlcally
to

the

temperature
gauge
WIthIn
the
vehIcle
dash

board

The

wax

pellet
m
the
thermostat

expands

when
heated
and
contracts
when
cold
The

pellet

IS
connected

through
a

pIston
to

a
valve

Expan

sion

pressure
IS
exerted

agalUst
a
rubber
dIa

phragm
which
forces
the
valve
to

open
and

per

rrut
coolant
to
flow

through
the
entIre

system

As
the

pellet
cools
contractIOn
allows

a

spnng

to
close
the
valve

Thermostat
Removal

1

Open
the
draIn
cock
on
the
bottom
of
the

radiator
and
dram
out

enough
coolant
so
that

the
level
In
the
radIator
IS
below
the
bottom
of

the

upper
radIator
hose

2
DIsconnect
the

upper
radIator
hose
from
the

water
outlet
elbow

3
Remove
the
two
nuts

holdIng
the
water
outlet

elbow
to
the
thermostat

housmg

4
Remove
the

gasket
and
thermostat
from
the

housmg
as
shown
m

FIgure
7

Thermostat

Inspection
and

Replacement

Submerge
the
thermostat
In
a

pan
of
water

Heat
the
water
and
momtor
the

temperature

2
The
thermostat
should
start
to

open
at

1796
1
27

degrees
F
82
1
1
5

degrees
C
Max

Imum

opemng
should
occur
at
203

degrees
F
95

ENGINE
ELECI
RlCAL
SYSTEM
9S

@

@

4
Test
the
COIls
for
shorts

by
unsoldermg
the

connectIons
of
each
coIl
and

repeatlng
the
test

given
m

step
3
If

a
defectIve
coil
IS
found
It

must
be

replaced

BRUSHES
AND
BRUSH
LEAD
WIRE

1
Check
condItIon
of
the
brush
contact
surface

and

general
wear
of
the
brush
If
the
brush
is

worn
to
under
02362
In

60mm
m

length

replace
It

Inspect
all
connectIons

carefully
for

looseness

or
cracks

Replace
or

reparr
as
re

qUIred

2
Check
the
connectIon
of
the
lead

clIp
and

WIre

3
Check
brush
holders
and

sprmg
clIps
for

damage
Replace
1f

they
will
not
hold
the
brushes

agaInst
the
commutator

properly
Clean
all

brushes
aIld
brush
holders

thoroughly

4
Check
brush

sprmg
tenSIon
WIth
a

spnng

scale
as
shown
m

Figure
14
The

reading
should

be
1
76
Ibs
0
8

kg
Replace
the

spnng
if
the

tenSIon
IS
under
1
54
Ibs
0
7

kg
@

ARMATURE
ASSEMBLY

1
Check
external

appearance
of
the
armature

and
commutator

2
Use
a

dIal

gauge
Figure
15
to
measure
the

armature
shaft
for
bend

Replace
the
armature

shaft
1f
the
bend
exceeds
0
001
in
0
08mm

@

3

Inspect
the
commutator
If
the
surface
IS

rough
sand

It
With
No
500

emery
paper
untIl

smooth
Use
a
dIal

gauge
to
check
the

commu

tator
If
out
of
round

IS
more
than
00079

In

0
2mm
or
the

depth
of
the

Insulatlng
mica
is

less
than
0
0079
In
0
2mm
from
the
commu

tator
surface
the
commutator
should
be
turned

on
a
lathe
Out
of
round
should
be
less
than

o
0020
in
0
05mm

Insulatmg
mica

should
be

undercut
as
shown

m

Figure
16

to
a

depth
of

from
0
0197
to
0
0315
in

0
5
to
0
8mm

4

Inspect
the

soldered
connectIon
of
the

arma

ture
lead
and
the
commutator
If
the
connection

is
loose
resolder
It

5

Usmg
a
clrcmt
tester
test
the
armature
for

ENGINE
ELECI
RlCAL
SYSTEM
97

No
Load
Lock

Torque
Test

1
Connect
the
starter
motor
in
series
with

a

12
volt

battery
and
antmeter
as
shown
in

Figure

19
The
antmeter
should
be

capable
of

mdIcatIng

1
000

amps

@
Switch

Voltmeter
Ammeter

2
Use

torque
testlng
equipment
to
determine

the

torque
the
motor

develops

3
Connect
a
voltmeter
and
a
vanable
resistor

WhICh
IS
used
to

regulate
the

voltage
Into
the

circwt

4
Close
the
sWitch

and

regulate
the

voltage
as

reqUIred
Figure
20

proVIdes

power
voltage

amperage
and

torque
mformatIon

that
1f
fol

lowed
will
mdIcate
the
condItion
of
the
starter

motor

Power
kw

Voltage
v

@

Test

Diagnosis

1
Low

speed
with

high
current
draw

might
re

sult
from

tIght
dirty
or
worn

bearings
bent

armatlIre
shaft
loose
field
call
or
a
shorted

armatlIre

2
Fatlure
to

operate
With

htgh
current
draw

may
result
from
a

gromlded
or

open
field
coil
a
defectIve
armature
coll
or
a
burned

out
com

mutator
bar

3
Low

torque
low
current
draw
and

low

speed

would
be
caused

by
hIgh
Internal
reSIStance
due

to
loose
connectIons

dirty
commutator
defec

tIve
leads
and

a
burned
out
commutator
bar

4

HIgh
speed
With
low

torque
would
be
caused

by
a

grounded
field
coll

Magnetic
Switch

Assembly
Test

H
the
above
tests
are

satIsfactory
check
the

magnetIc
SWitch

assembly
as
follows

1
Connect

Jumper
cables
between
the

negative

battery
tennmal
and
the
starter
motor
M
term

inal

as
shown
In

Figure
21
Also
connect
the

positIve
battery
terminal
to
the
S
terminal
and

place
a
SWitch
m
senes
in
the
CIrCuit

@
Ignition
switch

9

I

i
j

Battery
Starter
motor

rr

2
Close
the
SWitch
and
measure
the

dimension

given
m

Figure
22
The
dimensIon
should
be
as

specIfied

o
0591m

15mm

ENGINE
ELECTRICAL

SYSTEM

103

2
Check
the
lead

Wires
of
the
armature
coil

Includmg
the

neutral
wire

for

ground
as
shown

In

Figure
42

HIgh
reSIStance
no
current
flow

indicates

gqod
condItion

If

not
the
stator
must

be

replaced

DIODE

INSPECTION

The
diodes
can
be

inspected
through
the
use

of
a

lamp
and

battery
or
with

a
tester
The

lamp

and

battery
test
can
be
made
Without

disassembl

ing
the
alternator
wh1le
the

tester
should
be
used

when
the
dIodes

are

dIrectly
acceSSIble

1
Positive
Dwde
Test
Connect

the

battery

negative
terrmnal
WIth
the

connector
A
terrmnal

WhIte
and
the

battery

pOSItIve
terminal
With

the
connector
N

terrmnal

yellow
as
shown

m

Figure
43
The

lamp
m
the
circuit
should

hght

@

Reverse
the
connection
as

shown
m

Figure
44

If
the

lamp
does
not

hght
the

pOSItIve
diodes

are

satisfactory
If
the

lamp
does

light
one
or

all
of

the

pOSItIve
dIodes

are
defective
and
must

be

replaced
@

Qg

2

Negative
DIOde
Test

Connect
the

battery

negatIve
termmal
to

the
connector
N
terrmnal

yellow
and
the

battery

pOSItIve
termInal
to
the

connector
E
termmal

black
The

lamp
m
the

CIrcUit
should

lIght
Reverse

the
connectIons
If

the

lamp
does

not

lIght
the

nega1
ve
dIodes
are

satlsfactory
If
the

lamp
does

lIght
one

or
all

I

of
the

negatIve
dIodes

are
defectIve
and
must
be

replaced

To
test
the

indiVIdual
dIodes
With
a
tester

proceed
as
follows

1
There

are
two
kInds
of
diodes
as
shown
m

Figure
45
Check
dlOd
reSIstance

usmg
a
tester

In
both
dIrectIons

as

jl
own
in

Figure
46

f

Current
flow
@

Current
flow

re

ack

flgUre

e

terminal

r

Positive
diode

Negative
diode

@

106
CHAPTER
NINE

@

Igmtlon
switch

IgnItion

plug

engine

Condenser

IgnItIon
cod

@

II

9

ft

O

CHECKING
AND
ADJUSTMENT
foreIgn
matenal
or
cracks
Qean
the

cap
thor

oughly
Replace
it
If
cracks
are
found

Inspect

the

hIgh
tensIon
cables
to
see
that
all
connectIons

are

firmly
made
and
that
the
cables
are
not

cracked

Replace
any
defective
cables
Do
not

try
to

tape
or
mend
them
Cap
and
Rotor
Head

The

cap
and
the
rotor
head
must

always
be

kept
clean

to

prevent
lugh
voltage
leaks

Inspect

the

cap
penod1cally
for

SIgnS
of
carbon

bwldup

CHAPTER
TEN

EMISSION

CONTROL
SYSTEM

ThIs

chapter
covers
emission

control
and

exhaust

systems
The
emission

devices
used
in

clude
crankcase
ermssion

controls
an
exhaust

ermssion

system
and

evaporative
emission
con

trols

EXHAUST
EMISSION

CONTROL
SYSTEM

Two
methods
of
exhaust
emission

control
are

used

on
the
Datsun

One
is

an
aIr

injection

system
the
other
consists

of

engine
modifica

tIons
Datsuns

were

equipped
With
the
air

injec

tIon

system
only
through
1970
SInce
then
all

models

have
combined
aIr

mjection
with

engine

modIficatIons
EmisSIon

servicing
IS

complex

and

should
be
left
to

qualIfied

professionals

Figure
1

Illustrates
the

system
used

through

model

year
1969

Figure
2
IS
the

system
used

after
1970

Figures
3

through
7
offer
detaIls
of

various

emission

components

Maintenance
and

Testing

Penodlc

mspection
and
service

should
be

done

every
12
months

or
12
000
miles
The

engine
must
be

in

good
working
order
to
main

tain

a
low

level
of
harmful
emissions
There

fore

perform
a

general
tune

up
as

spec1fied
in

Chapter
Four
before

followmg
the

procedures

below
CRANKCASE
EMISSION

CONTROL
SYSTEM

The
crankcase

emission
control

system
is

shown
in

FlgDre
8
It
IS
a
closed

system
that

pre

vents
crankcase

gases
from

escaping
to
the
at

mosphere

Blowby
gases
are
dIrected

to
the

intake

manifold

through
the
ventilation

control

valve

Normally
capacity
of
the

valve
is

suffi

cient
to
handle
the

blowby

gas
plus
a
small

amount
of

ventIlating
air
drawn
from
the

air

cleaner

through
a
tube

leading
to
the
crankcase

Under
fun

throttle
condItIons
manifold
vacuum

is

Insufficient
to
draw
the

blowby
through
the

valve
When
this

happens
b10wby
flows

through

the

system
In
the
reverse
dIrection

General

1
Start
the

engine
and

bring

up
to

operating

temperature

2
Check

hoses
and
hose
connections
for

leaks

3

Examine
the
hoses
for

signs
of

cracks
or
de

terioraoon

Replace
as

required

Crankcase

Ventilation

Control
Valve

1
Start
the

engme

2
Remove

the
ventIlator
hose
from
the
crank

case
ventilatIon
control
valve
A

htssmg
nOISe