1968 DATSUN 510 fuel pump

CON1EN1S

CHAPTER
ONE

GENERAL
INFORMATION

Introduction

Model
Identification

CHAPTER
TWO

PERIODIC

MAINTENANCE

RoutIne
checks

Pen
odic
checks

CHAPTER
THREE

TROUBLESHOOTING

EqUIpment

Starter

ChargIng
system

EngIne

Igmtlon

system

Fuel

system

Exhaust

emIssIon
control

CHAPTER

FOUR

ENGINE
AND
IGNITION
TUNE
UP

EqUIpment

Battery

Spark
plugs

DIstrIbutor

Igmtlon

timIng

CHAPTER
FIVE

ENGINE
LUBRICATION
SYSTEM

Descnptlon

Lubncation

cIrcuIt
SpecIficatiOns
and
dImensIons

EngIne
lubncation
and

maIntenance

Recommended
lubncants

Clutch

TransmIssiOn

Brakes

Steenng
and

suspension

TIre
wear

analysIs

Wheel

balancIng

Idle

speed
and
Idle

mIXture

Dwell

angle
setting

CompressIon
test

Valve
clearance

adjustment

AddlllOnal
checks

Oil

pump
I

6

t
1

4

V

9
t

1

20

27

II

CHAPTER
SIX

ENGINE

Cylmder
block

Crankshaft

PistOns
and

connectmg
rods

Cyhnder
head

Camshaft

Valve
mechamsm

Camshaft
dnve

Mamfolds

011

pump

Fuel

pump
Carburetor

Emission
control
devIces

Engme
removal

Engme
dISassembly

Pistons
and

connectmg
rods

Cyhnder
head

Engme
mspectIon
and

replllr

Engme
reassembly

Service
data
and

speCifications

CHAPTER
SEVEN

FUEL
SYSTEM

Air
cleaner

Fuel
strlllner

Fuel

pump
Carburetor

Fuel
tank

1
CHAPTER

EIGHT

COOLING

SYSTEM

DescnptIon

Water

pump

Fan
clutch
Thermostat

Radiator

CHAPTER
NINE

ENGINE

ELECTRICAL
SYSTEM

Starter

Overrunmng
clutch

assembly

ChargIng
ClrcUlt

Alternator

Alternator

output

Voltage
regulator
DIstrIbutor

Condenser

Igrntlon
cod

SpeCifications

Spark
plugs

CHAPTER

TEN

EMISSION

CONTROL

SYSTEM

Exhaust
emiSSIOn

control

Crankcase

emission
control

Air

mJectlon
system
Engme
modifications

Evaporative
emiSSion
control

Exhaust

system

CHAPTER
ELEVEN

CLUTCH

TRANSMISSION
AND
DRIVESHAFT

Clutch

TransmissIon

Master

cyhnder
TransmissIon
data
and

speCIfications

Operating
cyhnder
Dnveshaft

Withdrawal
lever

adjustment
Dnveshaft
data
and

speCIfications

Clutch

system

bleedmg
Automatic
transmIssIon
checks

Clutch
data

and

speCIfications
31

62

84

91

114

127

PERIODIC

MAINTENANCE

7

Table
1
ENGINE

LUBRICATION
AND
MAINTENANCE

FREQUENCY
EVERY

E
E
E

E

E
E

E
Eo
00
00

00
00
00

00

00

gq
00

00

00

NO

t
r61li
0

CD

Check

engine
011
level

top
up
If

required
X

Change
engine
011
X

Lubricate

carburetor

hnkage
X

Lubricate
distributor
rotor
shaft
and
ann
shaft
X

Apply
grease
to
distributor
cam
heel
X

Check

radiator
coolant
level
X

Change
radIator
coolant
X

Change
radiator
coolant
additive

X

Check

battery

electrolyte
level
X

Check

specific
gravity
of

battery
X

Check

engine
starting
exhaust
color
X

Tighten

cyhnder
head

manifolds
and

pipe
flanges
X

Adjust
valve
clearance

X

Check

Ignition
timing
X

Tighten
carburetor

fittings
X

Check
fan
belt
tension
X

Check
for
011

pan
leakage
X

Tighten
engine
mounts
X

Check
fuel
strainer
X

Replace
fuel
strainer
X

Check
for
fuel
leaks
X

Replace
011
filter
X

Check

spark
plugs
X

Replace
spark
plugs
X

Check
dlstnbutor

cap
rotor
and

POints
X

Adjust
engine
Idle

speed
X

Check

air
cleaner

fittings
X

Clean
011
filler

cap
X

Clean

battery
cables
and
terminals

X

Check
alternator
and

voltage
regulator
function

X

Check

starter
motor
function

X

Replace
aIr
cleaner
element

X

Check
fuel

pump
function

X

Check

cyhnder

compressIon
X

Clean
carburetor

Jets
and
float
chamber

X

Check
dlstnbutor
condenser

X

Check
crankcase
ventilation
control
valve
X

10
CHAPTER
THREE

pressure
bUllt

up
In
each

cylInder
The

readIngs

when

properly
Interpreted
IndIcate

general
cyl

Inder
and
valve
condltlOn

Vacuum

Gauge

The
vacuum

gauge
IS

easy
to
use
but
dIfficult

for
an

Inexpenenced
mechanIC
to

Interpret
The

results
when
conSIdered
WIth
other

findIngs
can

prOVIde
valuable
clues
to

pOSSIble
trouble

Connect
the
vacuum

gauge
WIth

a
T
connec

tIon
In
the
hose
from
the
carburetor
to
the

vacuum
advance
on
the
dIstnbutor
Start
the

engme
and
let
It
warm

up
thoroughly
Vacuum

readIng
should
be

steady
at
18
22
Inches

NOTE
Subtract
1
Inch

from

reading

for

every
1000

feet
of
altitude

Figure
1
shows
numerous

tYPical
readIngs

WIth

InterpretatIons
Results
are
not
conclusive

WIthout

companng
to
other
tests
such
as
com

preSSIOn
readIngs

Fuel
Pressure

Gauge

ThIS
Instrument

IS
VItal
for

evaluatIng
fuel

pump
performance
Often

a
vacuum

gauge
and

fuel

pressure
gauge
are
combIned

Dwell
Meter

A
dwell
meter
measures
the
dIstance
In
de

grees
of
cam
rotatIon
that
the
breaker

pOInts

remaIn
closed
while
the

engme
IS

runnIng
SInce

thIS

angle
IS
determmed

by
breaker

pOInt
gap

the
dwell

angle
IS
an
accurate
IndIcatIon
of

pOInt

gap
Many
tachometers
Intended
for

tunIng
and

testIng
Incorporate
a
dwell
meter
as
well
Follow

the
manufacturer
s
InstructIon
to
measure
dwell

on
the
Datsun

Tachometer

A
tachometer
IS
essential
for

tunIng
Datsuns

WIth
exhaust
emission
control
deVices

IgmtIOn

turung
and
carburetor

adjustments
must
be

per

formed
at
the

specified
Idle

speed
The
best
In

strument
for
thIS

purpose
IS
one
WIth

a

range
of

0
1
000
or
0
2
000

rpm
Extended

range
0

6
000
or
8
000
Instruments
lack

accuracy
at

lower

speeds
The
InStrument
should
be

capable

of

detecting
changes
of
25

rpm
Stroboscopic
Timing
Light

ThIS
Instrument

pernuts
accurate

IgnitIon

tImIng
By
f1ashmg
a

bght
at
the

preCISe
Instant

cylInder
No
1
fires
the

posItIon
of
the
crank

shaft

pulley
at
that
Instant

can
be
seen
Marks

on
the

pulley
bne

up
With

a
reference

pOInter
on

the
block

dunng
the

tIming
procedure
SUltable

bghts
are
neon
bulb

types
and
xenon
strobe

hghts
Neon

tunmg
bghts
are
ddticult
to
see
and

must
be
used
in

dImly
bt
areas
Xenon
strobe

bghts
can
be
used
In

bnght
sunbght
Use
the

bght
accordIng
to
the
manufacturer
s
InStruC

tIons

Exhaust

Analyzer

Of
all
Instruments
descnbed
here
this

IS
the

least

bkely
to
be
owned

by
a
home
mechanic

One
Instrument

samples
the
exhaust

gases
from

the

taIlpIpe
and
measures
the
thermal
conduc

tIVIty
of
the
exhaust

gas
SInce
different

gases

conduct
heat
at

varYIng
rates
thermal
conduc

tIVIty
of
the
exhaust
IS

a

good
IndIcatIon
of

gases

present
This
Instrument
IS
VItal
for

accurately

checkIng
the
effectIveness
of
exhaust
emIssion

control

adjustments
but
IS
too

expenSIve
for
an

amateur
mechanIC
to
conSIder

buying

STARTER

Starter

system
troubles
are

relatIvely
easy
to

ISolate
The

followmg
are
common

symptoms

and
cures

1

Engme
cranks

very
slowly
or
not
at
all

Turn
on
the

headhghts
If
the

bghts
are

very
dun

most

likely
the

battery
or
the

connecting
WireS

are
at
fault

Check
the

battery
using
the

pro

cedures
descnbed

in
the
Tune

up
chapter
Check

wmmgfur
e
s
wom
andd
connectIom

H
the

battery
and

connectIng
WIres
check

good
turn
the

headlIghts
on
and

try
to
crank
the

engIne
H
the

lIghts
dIDl

drastIcally
the
starter
is

probably
shorted
to

ground
Remove
the
starter

and
test
it

usmg
the

procedures
gIven
in

Chapter

NIne
If
the

lights
remain

bnght
or
dun

slIghtly

when

crankIng
the

engme
the
trouble

may
be
in

the
starter
solenOId
or

wmng
To
ISolate
the

trouble
short
the
two

large
solenoid
ternunals

together
not
to

ground
if
the
starter
cranks

normally
check
the
solenoid
and

wmng
up
to
the

TROUBLESHOOTING
13

trouble

may
also
be
worn

bearings
Remove
the

alternator
and

repair

ENGINE

These

procedures
assume
the
starter
cranks

the

engme
over

normally
If
not
refer
to
Starter

section
m
this

chapter

1

Engme
won
t
start

Could
be

caused

by
the

IgOltlon
or
fuel

problems

First
determine
If

high
voltage
to

spark
plug

occurs
To
do
thiS
dISconnect
one
of
the

spark

plug
wires
Hold
the

exposed
wrre
termlOal
y
to

Y2
lOch
from

ground
any
metal
in

engine
com

partment
With
an
msulated
screwdriver
Crank

the

engme
over
If

sparks
do
not

Jump
to

ground

or
the

sparks
are

very
weak
the
trouble

may
be

10
the

IgnitIOn
system
See

Ignition
System
Trou

bleshootmg
to
further
check
If

sparks
occur

properly
the
trouble

may
be
10
the
fuel

system

See
Fuel

System
Troubleshootmg

2

Engme
misses

steadily

Remove
one

spark
plug
wrre
at
a
tune
and

ground
the
wrre
If

engme
mISs
increases
that

cyhnder
was
work

109
properly
Reconnect
the

wire
and
check
the
others
When
a
wire

IS
dIs

connected
and

engme
miss
remams
the
same

that

cylinder
IS
not

finng

Check

spark
as
descnbed
10

Step
1
If
no

spark

occurs
for
one

cyhnder
only
check
dlStnbutor

cap
wrre
and

spark
plug
If

spark
occurs

prop

erly
check

compressIOn
and
mtake
maOlfold

vacuum
to
ISolate
the
trouble

3

Engme
misses

erratlcally
at
all

speeds

Interrmttent
trouble
can
be
difficult
to
find
It

could
be
ill
the

Ignition
system
exhaust

system

or
fuel

system
Follow

troubleshooting
proce

dures
for
these

systems
carefully
to
isolate
the

trouble

4

Engme
misses

at
Idle

only

Trouble
could
exist

anywhere
ill

IgOltlon
system

Follow

Ignition
TroubleshootlOg
procedure
care

fully
Trouble
could
also
eXist
10
the
carburetor

Idle
crrcult
Check
Idle
mIXture

adjustment
and

check
for
restnctions
m
the
idle
crrcUlt

5

Engme
misses
at

high
speed
only

Problems
could
be
ill
the
fuel
or

IgOltlon
systems
heck
accelerator

pump
operation
fuel

pump

dehvery
fuel
hnes
etc
as
descnbed
under
Fuel

System
Troubleshootillg
Also
check

spark
plugs

and
wrres

6
Low

performance
at
all

speeds
poor

acceleratIOn

Trouble

usually
ill

IgOltlon
or
fuel

system
Check

each
With
the

appropnate
troubleshooting
pro

cedure

7
ExceSSive

fuel
consumptIOn

Could
be
caused

by
a

Wide

variety
of

seemmgly

unrelated
factors
Check
for
clutch

shppage

brake

drag
defective
wheel

beanngs
or

poor

front
end

alignment
Check

IgOltlOn
system
and

fuel

system

8
011

pressure
lamp
does
not

light
when

IgmtlOn

switch

IS
on

Check
the
alternator

warning
lamp
If
it
ISn
t
on

either

go
to

Step
1

Chargmg
System
Trouble

shootlOg
If

only
the
oil

pressure
lamp
IS
off

open

the

englOe
compartment
hd
and
locate
the
oil

pressure
sender
on
the
block
near
the
oil
filter

Make
sure
the
wrre
is
connected
to
the
sender

and

makmg
good
contact
Pull
the
wrre
off
and

ground
it
If
the

lamp
hghts
replace
the
sender

If
the

lamp
does
not

light
replace
the

lamp

9
011

pressure
lamp
lights
or

flickers
when

engme
IS

runmng

Indicates
low

or

complete
loss
of
oil

pressure

Stop
the

englOe
unmedmtely
coast
to
a

stop
With

the
clutch

dISengaged
Tlus

may

simply
be

caused

by
a
low
oil
level
or
an

overheatmg
en

glOe
Check
the
oil
level
and
fan
belt
tensIOn

Check
for
a
shorted
oil

pressure
sender
with
an

ohmmeter
or
a

contlOulty
tester
Remove
and

clean
the
oil

dipstick
and
check
oil
level
and

condition

RepleOlsh
or

replace
the
oil

as
re

qurred
Listen
for
unusual
nOISes

mdlcatmg
dam

aged
beanngs
etc
Do
not
re
start
the

engine

until

you
know

why
the

hght
went
on
and

are

sure
that
the

problem
has
been
corrected

IGNITION
SYSTEM

This

procedure
assumes
the

battery
IS
ill

good

enough
condition
to
crank
the

engme
at
a

normal
rate

14

CHAPTER
THREE

I
No

spark
to
one

plug

The

only

possible
causes
are
a
defective
dlStri

butor

cap
or

spark
plug
wrre
Examme
the
dis

tnbutor

cap
for
mOisture
drrt
or
carbon
track

ing
caused

by
flashover
cracks
etc

2
No

spark
to

any

plug

ThlS
could
mdicate
trouble
in
the

prImary
or

secondary
Circuits
Frrst

remove
the
coil
wire

from
the
center

post
of
the
dlStributor

Hold
the

Wire
end
about
1
1
mch
from

ground
With
an

msulated
screwdrIver

Crank
the

engme
H

sparks
are

produced
the
trouble
is
m
the
rotor

or
distributor

cap
Remove
the

cap
and
check

for
burns

mOisture
dirt
carbon

trackmg

cracks
etc
Check
the
rotor
for
excessive
burn

mg
pittmg
or
cracks

Replace
both
rr

necessary

H
the
cod
does
not

produce
any
spark
check

the

secondary
Wire
for

opens
H
the

wrre
is

good

turn
the

engme
over

so
the

breaker

pomts
are

open
Examme
the

points
for
excessIVe

gap

burmng

pittmg
and
looseness

Replace
and
ad

Just
rr

necessary
With
the

points
open
check

voltage
to

ground
at
the
cod
with
a
voltmeter
or

test

lamp
If

voltage
is

present
the
cOlllS

prob

ably
bad
Have
it
checked
or

substitute
a
known

good
one

If

voltage
is
not

present
check
wrre
connec

tions
to
cOll
and
distrIbutor

Temporanly
dIs

connect
the
Wire
from
the
distrIbutor

to
the
cOll

and
measure
from
the
coli

to

ground
If

voltage

is

present
the
distnbutor

lS
shorted

Examme

the
breaker

pomts
and

connecting
WIres
care

fully
If

voltage
is
still
not

present
check
the

other
coli
termmal
for

ground
Voltage
at
thiS

termmal
but
not
at
the
other
mdicates
a
defecnve

cOll
No

voltage
at
tlus

termmal
mdicates
an

open
Wire
between
the

termmal
and
the

battery

3
Weak

spark

If
the

spark
lS
so
small
it

cannot

Jump
from
the

wrre
to

ground
check

battery
condinon
Other

causes

are
bad
breaker

points
condenser
m

correct
breaker

pomt
gap
dirty
or
loose
con

necnons
m
the

pnmary
crrcuit
or

dirty
or
burned

rotor
or
distnbutor
Also
check

for
worn
dis

tnbutor
cam
lobes

4

Mlssmg

ThiS
is

usually
caused

by
fouled
or

damaged

plugs

plugs
of
the

wrong
heat

range
or
mcorrect
plug
gap
Clean
and

regap
the

spark
plugs
flus

trouble
can
also
be

caused

by
weak

spark
see

symptom
3
or
mcorrect

igmnon
tlIDing

5

Spark
polarity

Less

voltage
is

requrred
to
cause
electron
flow

from

a

relatively
hot
electrode
to
a
cooler
elec

trode

Smce
the
center
electrode
is
hottest
this

electrode
should
be

negative
Electron
flow
lS

then
from
the
center
electrode
to
the
outer
elec

trode
From
20
to
40

percent
more

voltage
is

requrred
to
cause
electron
flow
from

the
outside

electrode
to
the
hotter

center
electrode
This

occurs
when
the

spark

voltage
is

positive
The

cOll
wrres
must
be

connected

correctly

FUEL
SYSTEM

Fuel

system
troubles
must
be
iSolated

at
the

carburetor
fuel

pump
or
fuellrnes
These

pro

cedures
assume
that
the

igmtlon
system
has

been

checked
and

properly
adjusted

I

Engme
Will

not
start

Frrst
detenmne
that
fuellS

reachIng
the
carbu

retor
Remove
the

au
cleaner
look
into
the

carburetor
throat

and

depress
the
accelerator

several
tlIDes

There
should
be
a
stream
of
fuel

from
the

discharge
tube
each
time
the
accelerator

lS

depressed
If
not
the
fuel

pump
lS
not
dehver

mg
fuel
to
the
carburetor
or
the
float

system
m

the
carburetor
lS
not

workmg
Make

certam

there
is
fuel
m
the
fuel
tank
Check
the

automatic

choke
rr
so

equipped
to
make

certain
it
is
not

stuck
If

necessary
rebudd

the
fuel

pump
or

overhaul
the
carburetor

whichever
lS
determmed

to
be

faulty

2

Engme
runs

at

fast
Idle

Usually
thiS
is
caused

by
misadJustment
of
the

carburetor
idle

setting
Readjust
as

required

3

Rough
Idle

or

engme
miss
with

frequent

stallmg

Check
idle
miXture

and
idle

speed
adjustments

Inspect
the

overall
conchtlOn
of
the
carburetor

for

foreign
material
and
clean

or
overhaul

as

required

4

Engme
diesels

contmues
to
run

after

engme
IS
turned

off

Check
idle
IDlXture

and
idle

speed
adjustments

TROUBLESHOOTING

15

5

Stumbling
when

acceleratmg
from
Idle

Check

accelerator

pump
diaphragm
and
Idle

speed
adjustment

6

Engine
mISses
at

hIgh

speed
or
lacks

power

This
mdlcates

pOSSible
fuel
starvatIon
Check

fuel

pump
pressure
and

capacIty
Clean
main

Jet

and
float
needle

valve

7
Black
exhaust
smoke

Black
exhaust
smoke
means
a

badly
ovemch

nuxture
Check
Idle

mIXture
and
Idle

speed
ad

Justment
Check
for
excessive
fuel

pump
pres

sure
or
blocked
return
hne
from
carburetor

to

fuel
tank
Check
for

leaky
float
or
worn
needle

valve

8
ExceSSIve

fuel

consumptIOn

ThIS

may
be
another
mdIcatIon
of

an
ovemch

fuel
mixture
Check
that
automatIc
choke

oper

ates

If
so

eqUIpped
or
that
the
manual
choke

contraIlS
not

being
left
out
Check
Idle
mIXture

and
Idle

speed
Check
for
excessIve
fuel

pump

pressure
leaky
float

or
worn
needle

valve
Make

certam
that

jets
are
the

proper
SIZe

Fuel

Pump
Pressure

Testing

1
Install
a
T

fittmg
m
the
fuel
hue

close
to
the

carburetor

2
Connect
a
fuel

pressure

gauge
to
the

fittmg

WIth
a
short
tube

3
Check
fuel

pump
pressure
as
described

in
the

Fuel

System
chapter

EXHAUST
EMISSION
CONTROL

The

followmg
symptoms
as
ume

you
have
ad

justed
the

Ignition
and
carburetor

to

specdicatIon

and
that

you
have
checked

the
results
on
an

accurate
exhaust

gas
anajyzer

1
CO

content
too
low

Make

sure
Idle

speed
IS
not
too
low
Check
Idle

mIXture

adjustment
too
lean
Check
carbu

retor

Jets
and

channels
Clean
and
or

replace
as

necessary
Check

engme
condition
With
a
com

pressIOn
and
vacuum
test

2
CO
content
too

hIgh

Check
Idle
mixture

adjustment
too

nch
Check

for

dIrty
air
cleaner

and
defectIve

automatIc

choke
If
so

equipped
Check
carburetor

Jets
and
channels
Clean
and
or

replace
as

necessary

Check

engme
condItIon
WIth

compression
and

vacuum
test

3

Hydrocarbon
level
too

hIgh

Check
that

Idle

speed
and
mIXture

adjustments

are

to

specIfication
Check

spark
plug
condItIon

and

gap
Check
breaker

pomts
Check

IgnItIon

tnumg
too

early
Check
mtake

mamfold
for

leaks
Check

valve
clearance
too

small
Check

condItIon

of
valves
With

compressIOn
test

MANUAL
CLUTCH

1

SlIppage

ThiS

is
most

noticeable
when

acceleratIng
m
a

hIgh
gear
at

relatIvely
slow

speed
To

check

slip

page
park
the
car
on

a
level
surface

WIth
the

handbrake

set
ShIft
to
2nd

gear
and
release
the

clutch

as
If

drlVing
off
If
the

clutch
is

good
the

engme
will
slow
and
stall
If
the

clutch

shps
con

tInued

engme
speed
will

gIve
It

away

CAUTION

ThIS
IS
a
severe

test

Perform

only

when

slippage
IS

suspected
not

penodlcally

Shppage
results
from
IDSufliclent
clutch

pedal

free

play
all
or

grease
on
the

clutch
disc

worn

pressure
plate
or
weak

sprmgs
Also
check
for

bIndIng
m
the
clutch
cable

and
lever
arm
which

may

prevent
full

engagement

2

Drag
or

failure
to
release

ThIS

problem

usually
causes
dIfficult

shIftIng
and

gear
clash

espeCially
when

downshIftmg
The

causes

may
be
excessive
clutch

pedal
free

play

warped
or
bent

pressure
plate
or
clutch
dISC
ex

cessive
clutch
cable

guide
sag
and
broken
or

loose
clutch

lmings
Check
conditIOn
of

mam

shaft

splines

3
Chatter
or

grabbing

A
number
of

thmgs
can
cause

tIns
Check

cable

gUIde
sag
and

tIghtness
of
transnusslOn
to
frame

and

engme
to
transmlSslon

mountIng
bolts

Check
for

worn
or

mISaligned
pressure
plate
and

misalIgned
release

plate

4

Other
nOIses

NOISe

usually
mdlcates
a

dry
or
defective
release

bearIng
Check
the

beanng
and

replace
If
neces

22
CHAPTER

FOUR

CD

Normal

plug

appearance
noted

by
the
brown
to

graYish
tan

deposits
and

slight
electrode

wear
This

plug
rndlcates
the
correct

plug
heat

range
and

proper
air
fuel
ratio

f

j

l

Carbon

fouling

dlstrngUlshed
by
dry
fluffy
black

carbon

deposits
which

may
be
caused

by
an
over

nch
alr
fuel
mixture
excessIVe

hand

chokrng

clogged
air
filter

or
excessive
Idling

lJ
6

1

4i

Z

011

fouling
rndlcated

by
wet

OIly

depOSits
caused

by
011

pumprng
past
worn

rrngs
or
down
the
rntake

valve

gUides
A
hotter

plug
temporanly
reduces
011

depOSits
but
a

plug
that
IS

too
hot
leads
to

pre

IgmtlOn
and

possible
engrne
damage
Red
brown

yellow
and
white

coatrngs
caused

by

fuel
and
011
additives
These

depOSits
are
not
harm

ful
If

they
remarn

rn
a

powdery
form

C

I

Shrny
yellow
glaze
on
rnsulator

cone
IS
caused

when

the

powdery
depOSits
from
fuel
and
011
additives

melt

Meltrng
occurs
dunng
hard

acceleration
after

prolonged
Idling
This

glaze
conducts

electnclty

and
shorts

out
the

plug

Overheated

plug
rndlcated

by
burned
or
blistered

rnsulator

tip
and

badly
worn
electrodes
This
condl

bon

may
be
caused

by
pre
Igmtlon
cooling
system

defects
lean
air

fuel
ratiOS
low
octane
fuel
or
over

advanced

Igmbon
bmrng

Spark
plug
condition

photos
courtesy
of
At

Spark
Plug
DIvision
General
Motors

Corporation

The

procedures

given
below
would

generally

apply
to
eIther

type
In
the
dual

pomt
system

one
set
of

pomts
IS
known
as
the
advance
set

and
the
other
the
retard
set

Complete
details

are

given
m

Chapter
Nme

Figure
4
IS
a
detaIl

of

the
dual

pomt

system

1
Remove
dIStnutor

cap
Clean

It

carefully
to

remove

grease
or
dIrt

2
Examme
the
mSIde
of
the

cap
for
d1rt
or
ex

ceSSIve
wear
Look
for

SIgns
of
carbon
tracks
arcmg
from
contact
to
contact
mSIde
the
dIS

trIbutor

cap
Carbon
tracks
mdlcate
defects
or

cracks
and
If
found
the

cap
should
be

replaced

3
Remove
the
rotor
and

mspect
for
exceSSIve

wear
around
the

top
metal
contact

wiper
surface

If

defectlve
replace
As

a
matter
of

good

prac

nce
the

rotor
should
be

replaced
whenever
the

contact

pomts
are

replaced

4
Use
a
screwdriver
to

gently
open
the
contact

pomts
If

they
show
wear
or

plttmg
remove
the

I

7
r