engine overheat DATSUN 510 1968 Service Repair Manual

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

ENGINE
ELECI
RICAL

SYSTEM

113

i

Normal

plug
appearance
noted

by
the
brown

to

graYlsll
lan

depOSits
and

slight
eleclrode

wear
This

plug
indicates
the
correct

plug
heal

range
and

proper
air
fuel

ratio

jI

Jo

t
Ql
i

Carbon

fouhng

distinguished
by

dry
fluffy
black

carbon

depOSits
which

may
be
caused

by
an

over

rich

alr
lue
mixture
excessive
hand

choking

clogged
air

filler
or
excessl
e

Idling

t
I

j
if

r
l

1

tfc
ji

0
1

fouling
indicated

by
wet

o
ly
depOSits
caused

by
011

pumping
past
worn

rings
or
down
the
Intake

valve

gUIdes
A
hotter

plug

temporanly
reduces

011

depOSits
but
a

plug
that
IS

too
hot
leads

to

pre

Ignition
end

possible

engine
damage
@

Red
brown

yellow
and
white

coatings
caused

by

luel
and
011
addltl

es
These

depOSits
are

not
harm

ful
If

they
remain
In
a

powdery
lorm

pr

11

L
J

J

S

C

ShinY
yellow

glaze
on
Insulalor
cone
IS

caused
when

the

powdery

depOSits
from
fuel

and
011
addltl
es

melt

Melting
occurs

during
hard

acceleration
alter

prolonged
Idling
This

glaze
conducts

electnclty

and

shorts
out
the

plug

e

1

A
I

A

I

7

Overheated

plug
indIcated

by
burned

or
blistered

Insulator

tiP
and

badly
worn
electrodes
ThiS
condl

J

tlon

may
be

caused

by
pre
Ignition

cooling
system

defects
lean
alr

luel
ratiOS
low
octane
luel

or
o
er

advanced

Ignition
timing

Spark
plUI
condition

photos
courtesy
of
AC

SPIr1l
Plug
Olv
s
on

Gene
MolDrs

Corporlllon