compression ratio DATSUN PICK-UP 1977 Service Manual

Yellow

line

Spark
delay
valve
to

distributor

Spark
delay
valve
to
vacuum
tube

Distributor

to
vacuum
tube

Vacuum
tube
to
carburetor

Vacuum
tube
to
canister

Green
line

Anti

backfire
valve
to
intake
mani

fold

Air

control
valve
to

emergency
air

relief
valve

Intake
manifold
to
vacuum
hose

connector

Intake

manifold
to
canister

CHECKING
ENGINE

COMPRESSION

COMPRESSION
PRESSURE

TEST

I
Warm

up
engine
sufficiently

2
Disconnect

all

spark
plugs

3
Disconnect
anti

dieseling
solenoid

valve
connector

4

Properly
attach
a

compression

tester
to

spark

plug
hole
in

cylinder

being
tested
Engine
Tune

up

I

ET010
Different

compression
in
two
or

more

cylinders
usually
indicates

an

improperly
seated
valve
or
broken

piston
ring

9
Low

compression
in

cylinders
can

result
from
worn

piston
rings
This

condition

may
usually
be

accompanied

by
excessive

fuel

consumption

TEST
RESULT

If

compression
in

one
or
more

cylinders
is
low

pour
a
small

quantity

of

engine
oil
into

cylinders
through

the

spark
plug
holes
and
retest
com

pression

I

If

adding
oil
increases
the
com

pression
pressure
the
chances
are
that

rings
are

faulty

2

If

pressure
stays
low

probable

cause
is

that
valve
is

sticking
or

seating

improperly

3
If

cylinder
compression
in

any

two

adjacent
cylinders
is

low
and
if

adding
oil
does
not

help
the

compres

sian
there
is

leakage
past
the

gasket

surface

Oil
and
water
in

combustion
cham

bers

can
result
from

leakage

IGNITION
AND

FUEL
SYSTEM
Fig
ET
10

Teding

compression

pressure

5

Depress
accelerator

pedal
to

open

throttle
and
choke
valves

Note
Do

not

pump
pedal

6
Start

engine
as

quickly
as

pos

sible

7

Compression
pressure

kg
cm2

psi
at

rpm

Standard

12
0

171
350

Minimum

9

0
128
350

8

Cylinder
compression
in

cylinders

Should
not
be
less
than

80
of

highest

reading

CONTENTS

CHECKING
BATTERY
ET
9

CHECKING
DISTRIBUTOR
CAP
ROTOR

CHECKING
AND

ADJUSTING
IGNITION
AND
CONDENSER
ET
11

TIMING
ET
10

CONDENSER
ET
11

ADJUSTING
IGNITION
TIMING
ET10

ADJUSTING
CARBURETOR
IDLE
RPM

CHECKING
AND
REPLACING
SPARK
PLUG
ETlO
AND
MIXTURE
RATIO
ET

11

CHECKING
DISTRIBUTOR
OPERATING
IDLE

LIMITER
CAP
ET
12

PARTS
AND

IGNITION
WIRING
ETlO
CHECKING
CARBURETOR
RETURN
SPRING
ET

12

BREAKER
POINTS

lNon
California
models

ET
10
CHECKING
CHOKE
MECHANISM

AI
R

GAP
lCalifornia
models
ET11
Choke

plate
and

linkage
ET13

DISTRIBUTOR
ET
11
CHECKING
FUEL

LINES

IGNITION
WIRING

ET
11
Hoses

pipings
connections
etc

ET
13

REPLACING
FUEL
FILTER
ET
13

CHECKING
BATTERY

Check

electrolyte
level
in

each
bat

tery
cell
I
Unscrew

each
filler

cap
and

inspect
fluid
level
If
the
fluid
is
low

add
distilled
water
to

bring
the
level

up
approximately
10
to
20
mm
0
39

H
9
to
0
79

in
above
the

plates
Do
not

overfill

2
Measure
the

specific
gravity
of

battery
electrolyte

Engine
Tune

up

TROUBLE
DIAGNOSES
AND

CORRECTIONS

Condition
Probable
cause

CANNOT
CRANK

ENGINE
OR

SLOW

CRANKING
Improper
grade
oil

Discharged
battery

Faulty
battery

Loose

fan
belt

Malfunction
in

charge
system

Wiring
connection
loose
in

starting
circuit

Faulty
ignition
switch

Faulty
starler
motor

Trouble

shooting
procedure
on

starting
circuit

Switch
on
the

starting
motor
with

light
ON

When

light
goes
off
or
dims

considerably

a
Check

battery

b
Check
connection
and

cable

c
Check
starter
motor

When

light
stays
bright
Corrective
action

Replace
with

proper
grade
oiL

Charge

battery

Replace

Adjust

Inspect

Correct

Repair
or

replace

Repair
or

replace

a
Check

wiring
connection
between

battery
and
starter

motor

b
Check

ignition
switch

c
Check
starter
motor

ENGINE
WILL
CRANK

NORMALLY
BUT

WILL
NOT

START

In
this
case
the

following
trouble
causes

may
exist

but
in

many
cases

ignition

system
or
fuel

system
is
in

trouble

Ignition

system
in
trouble

Fuel

system
in
troubk

Valve
mechanism
does
not
work

properly

Low

compussion

Trouble

shooting
procedure

Check

spark
plug
firstly
by

following
procedure

Disconnect

high
tension
cable
from
one

spark
plug
and
hold
it

about
10
mm
0
39
in

from
the

engine
metal

part
and
crank

the

engine

Good

spark
occurs

Check

spark
plug

b
Check

ignition
timing

c
Check
fuel

system

d
Check

cylinder
compression

Check
the
current
f10
in

primary
circuit

Very
high
current

Inspect
primary
circuit
for
short

Check
breaker

poiIit
operation

except
tran

sistor

ignition
system
No

spark
occurs

ET

27

Engine
Mechanical

GENERAL
DESCRIPTION

MODEL

L20B
ENGINE

CYLINDER
BLOCK

CRANKSHAFT

PISTON
AND
CONNECTING
ROD

CYLINDER
HEAD
CONTENTS

EM
2

EM
3

EM
3

EM
3

EM
3
CAMSHAFT

VALVE
MECHANISM

CAMSHAFT
DRIVE

MANIFOLDS

out
smooth

dependable

power

The

cylinder
block
is
cast
as
a

single

unit

and

featllres
deep
skirting
This

engine
is

equipped
with
a

single
2

barrel
downdraft
carburetor
that
in

corporates
a

special
device
to
control

emissions
MODEL
L20B

ENGINE

The
L20B

engine
features
O
H
C

valves

wedge
shaped
combustion

chamber
aluminum
head
and
a

fully

balanced
5

bearing
crankshaft
to
turn

Main

specifications

Oisplacemen
t
cc

cu
in

Bore
x
stroke

mm
in

Compression
ratio

Ignition

timing

Degree
B

T
O
C

rpm
MIT

AlT

MIT
Manual
Transmission
EM535

Fig
EM
Cross
sectional
view

L20B

1

952
1191

85

X
86

3
35
x
3
39

8
5

12
750

Non
California

model

10
750

California

model

12
650
in
0
position

AIT
Automatic
Transmission

EM

2
EM
3

EM
3

EM
3

EM
3

CYLINDER
BLOCK

The

cylinder
block
a
mono
block

special

casting
structure

employs
a

five
bearing

support

system
for

quiet

ness

and

higher
durability

The

cylinder
bores
are
surrounded

by
cooling

jackets
and
machined
di

rectly
in
the
block
The
oil

ways
in
the

block

are
arranged
so
that
the

full
flow

oil
filter
is

directly
attached
to
the

right
hand
side
of
the
block

EM536

Fig
EM

2
Cylinder
block

CRANKSHAFT

The
crankshaft
is

a

special
steel

forging
Fully
balanced
it
turns
out

smooth

dependable
power
at

high

speed

The
L20B

engine
uses

eight
balance

weights

Main

bearings
are
lubricated

by
oil

pumped
through
the
main
oil

gallery

and
the
oil
holes
which
run
in

parallel

with

cylinder
bores
There

are

oilways

drilled
in

the
crankshaft
for
the
lubri

cating
oil
The
center
main

bearing
is

equipped
with
thrust
washers

to
take

up
end

thrust
of
the
crankshaft

Fig
EM

3

Crankshafl

PISTON

AND

CONNECTING
ROD

The

pistons
are

of
a

special
alumi

num

casting
and
have

struts
to
control

thermal

expansion
two

compression

rings
and

one
combined
oil

ring
The

piston
heads

are
slightly
dished

The

piston
pil1S
are
a

special
hollow

steel

shaft

They
are
full

floating
fit
to
the

piston
and

press
fit
to
the

connecting

rods

The

connecting
rods
are
of
a

special

forged
steel
Oil
is

sprayed
to
the

connecting
rod
small
ends

through

drilled

passages
in

the

large
ends
of

rod

Oil
holes
in

the

connecting
rods

are
located
so
as
to
insure

optimum

lubrication
under

heavy
load

0
50
1

o

E

Moao

Fig
EM
4

Piston
and

connecting
rod

CYLINDER
HEAD

The

cylinder
head
is

made
of
a

light
strong
aluminum

alloy
with

good

cooling
efficiency
it
contains

wedge

type
combustion
chambers
A

special

aluminum
bronze
valve
seat
is

used
on

the
intake
valve
while
a
heat
resistant

steel
valve
seat
is
installed

on
the

exhaust
valve
These

parts
are

all
hot

press
fitted

EM407

Fig
EM
S

Cylinder
head
Engine
Mechanical

CAMSHAFT

The
camshaft
is

made
of
a

special

cast
iron
and
is
loca
ted
inside
the

rocker
cover
Four
aluminum

alloy

brackets

support
it
Camshaft

bearings

are
lubricated
from
oil
holes
which

lead
to
the

main
oil

gallery
of
the

cylinder
head

Concentric

passages
are
drilled
in

the

front
and

rear

parts
of
the

earn

shaft

Oil
to
each
earn
lobe
is

supplied

through
an
oil

hole
drilled
in
the
base

circle
of
each
lobe
Lubricant
is

sup

plied
to
the
front
oil

gallery
from
the

2nd
camshaft

bearing
and
to
the

rear

oil

gallery
from
the

3rd
camshaft

bearing
These

holes
on
the
base

circle

of
the

lobe

supply
lubricant
to
the

earn

pad
surface
of
the
rocker
arm

and

to
the
valve

tip
end
The
cams
feature

a

long
overlap
profile
to
reduce
NOx

emission

Fig
EM
6

Camshafl

VALVE
MECHANISM

The
valve

system
has
the

pivot
type

rocker

arms
that

are
activated

directly

by
the
earn
mechanism

this
has
made

its

moving

parts
considerably
lighter

and

provides
ideal

high
speed
perform

ance

Dual

type
valve

springs
are
in

stalled

h

@l

if

Exhaust

Intake
EM084

Fig
EM
7
Valve
mechanism

EM

3
CAMSHAFT
DRIVE

The
camshaft
is
driven

by
a
double

row
roller
chain
driven

by
the

crank

shaft
The
tension
of
the

chain
is

controlled

by
a

chain
tcosioner

which

is

operated
by
spring
and
oil

pressure

The
rubber
shoe

type
tensioner

damps

vibration

of
the

chain
and
controls
its

tension

EM537

Fig
EM

8
Chain

driving

aystem

MANIFOLDS

The
intake
manifold
is
of
an
alumi

num
cast

alloy

The
exhaust
manifold
is

of
a
dual

design
and

incorporates
a
heat
control

valve
in
it
The

heal
control
valve
is

used
to

warm
the
intake
manifold

A

plate
is
installed
on
the
outer

face
of
the
manifold
to
draw
hot

intake
air

out

through
it
The
exhaust

pipe
is
connected
to
the

flanged
sur

face
of
the
exhaust
manifold

Fig
EM

9
Intak
and
exhaust

manifolds

r

28
Remove

cylinder
head

assembly

Use

Cylinder
Head
Bolt
Wrench

STl0120000
to

remove

cylinder
head

bolts
Loosen
bolts

from

CD
to

@
as

shown
in

Figure
EM
18

Fig
EM
IS

Cylinder
head
bolt

loosening
equence

Notes
When

removing
cylinder
heao

from

engiJJe
installed

on
car
follow

the

instructions
below

a
Turn
crankshaft

until
No
I

pilton

is
at
T
D
C

on
its

compression

stroke

b
Remove

rocker
Cover
and
fuel

pump

c
To
facilitate

assembling
o
tion

scribe
8
mark

on

timing
c
8in

and

camshaft

sprocket
with

paint
be

fore
removal

d
Loosen
camshaft
bolt

and
remove

fuel

pump
drive
earn

e

Support
timing
chain

by

utilizing

Chain

Stopper
STl7420001
bet

ween

timiilg
chains
as
shown
in

Figure
EM
19

This
0

peration
eliminates

the

prob

lem
of

realigning

timing
marks

on

timing
chain
and
crankshaft

sprocket

EM538

Fig
EM
19

Supporting
timing
chain

f

Remove
camshaft

sprocket

g
Loosen

cylinder
head
bolts

and

remove

cylinder
head
Engine
Mechanical

29
Invert

engine

30

Remove
oil

pan
and

oil
strainer

EM094

Fig
EM
20

Removing
oil
traintir

and
oil

pump

31

Remove
oil

pump
and
its
drive

spindle
See

Figure
EM
20

32
Remove
front
cover

33

Remove
chain
tensioner

and

chain
slack
side

guide

EM095

Fig
EM
21

Removing
chain
ten
ioner

and
tim

ing
chain

34
Remove

timing
chain

See

Figure
EM
2l

35
Remove

oil
thrower
crankshaft

wonn

gear
and

chain
drive

sprocket

Fig
EM
22

Removing
chain
drive

Proc
et

EM
6
36
Remove

piston
and

connecting

rod

a

mbly
Extract

connecting
rod

bearings
keeping
them
in
order

I

Fig
EM
23

Removing

pilton
and

connecting
rod
aat
m
b

y

37

Remove

flywheel
and

rear

plate

Be

careful
not

to

drop
them

EM415

Fig
EM

24

Removing
flywheel

38
Remove
main

bearing
caps

Use
Crankshaft

Main

Bearing

Cap

Puller
KVIOI04ISO

to
remove
center

and
rear

main

bearing

caps
Keep
them

in
order

KVIOI04IS0

EM539

Fig
EM
25

Removing
rear

main

bearing

cap

39

Remove
two
side
seals
from

rear

main

bearing
ca

p

40
Remove
rear
oil

seal

Engine
Mechanical

SERVICE
DATA
AND
SPECIFICATIONS

GENERAL
SPECIFICATIONS

Engine
model
L20B

Cylinder
arrangement

Displacemen
t

Bore
and
stroke
4
in

line

cc
co
in

mm
in
1

952

J
19
1

85
x

86
3

35
x
3
39

O
H

C

I

3
4
2
Valve

arrangement

Firing
order

Engine
idle
rpm

Manual
transmission

Automatic
transmission
in
D

range
750

650

8
5

Compression
ratio

Oil

pressure
Warm
at
2

000

rpm

kg
cm2

psi
3
5
to
4
0
50

to
57

SPECIFICATIONS

a
Valve
mechanism

Valve

clearance
Warm

Intake

Exhaust

Valve
clearance
Cold

Intake

Exhaust

Valve
head
diameter

Intake

Exhaust

Valve
stem
diameter

Intake

Exhaust

Valve
length

Intake

Exhaust

Valve
lift

Intake
and
exhaust
mm
in

0
25
0
010

0
30
0
012

mmOn

0
20
0
008

0
25
0
010

mm
in

42
0
to
42
2
1
654

to
1

661

35

0
to
35
2
1

378
to
1
386

mm
in

7

965
to
7
980
0
3136
to

0
3142

7
945
to
7
960
0
3128
to

0
3134

mmOn

114
9
to
115
2
4
524
to
4
535

115
7
to
116
0
4
555
to
4

567

mmOn

Valve

spring
out

of

square
mm
in
10
5
0
413

less
than
1

6
0
063

Valve

spring
free

length
mm
in

Intake
and
exhaust
Outer

Inner
49
98
1
968

44

85
J
766

EM
27

SHOCK
ABSORBER

REMOVAL
AND

INSTAUATION

1
Raise
vehicle
on
a
hoist
or
stands

2
Remove

wheel

3
Hold
the

upper
stem
of
shock

absorber
and

remove
outs
washer

and

rubber
bushing

4

Remove
bolt
from
the
lower
end

of
shock
absorber

FA232

Fig
FA

13
Shock
absorber

S
Retain

lower
rubber

bushing
in

position
install
the

lower
end
of
shock

absorber
to
the
bracket
of
lower
link

and

torque
the
bolt

to
3

1

to
4

1

kg
m

23
to
30
ft
lb

Note
Insert
the
bolt
from
the
front

side
of
vehicle

6
Install
the

upper
end
of
shock

absorber
to

body
bracket
and

tighten

lock

n
Jt
to
the

specifjcations

Tightening
torque

1

6
to
2

2

kg
m
121016
ft
lb

INSPECTION

I

Check
shock
absorber
for
visible

defects
and
oil

leaks
Place
shock

absorber

vertically
in

a
vise
and
hand

stroke
shock
absorber

as
outlined
be

low

Extend
and

compress
shock
ab

sorber

as
faI

as

possible
travelling
as

long
as

possible

If
smooth

hydraulic
resistance
is

not

present
in

bqth
Iirection
replace

absorber

2

Replace
rubber

bushing
if
crack

or
deterioration
is
detected
Front
Axle
Front

Suspension

Specifications
for

shock
absorber

Model

Item

Piston
stroke

mm
in

Damping
force

kg
lb

0
3

m
sec
0

98
ft
sec

j

Rebound

Compression

STABILIZER

REMOVAL

AND

INSTAUATION

I

Raise
vehicle
on
a

hoist
or
stands

2

Remove
wheel

3
Loosen

secUring
nut
at
the
lower

link
side
of

stabilizer

4

Remove
bolt

securing
stabilizer

mounting
bracket

to
chassis
frame

Install
stabilizer
in

the
reverse
se

quence
to
removal

noting
the
follow

ing
instructions

S
Attach
stabilizer

mounting
brack

et
to
chassis
frame

tightening
bolt
to

1
6
to
2
2

kg
m
12

to
16
ft

lb

torque

6
Install
stabilizer
lower
link
side

to

connecting
rod
and

tighten
nut
to
the

specifications
as
shown

in

Figure

FA
14
Then

torque
lock

nut
toJ
6

to

2
2

kg
m
12
to

16
ft
lb

F

A233

Fig
FA
14
Stabilizer
detail

INSPECTION

Check

stabilizer
for
deformation

FA
S
All
models

110
4
3

76
168

38
84

and
rubber

bushings
for

crack
wear

and
deterioration

Replace
if
ne

cessary

TENSION
POD

REMOVAL
AND

INSTALLATION

I

Raise
vehicle
on

a
hoist

or
stands

2
Remove

wheel

3

Remove
nuts

CD
from

both
ends

of
tension

rod

4

Remove
bracket
bolt

@
from
the

front
end
of
tension
rod
and
remove

tension
rod

with
bracket

CD

@

f
A234

Fig
FA
15
Ten
ion
rod

Install
tension

rod
in

reverse
00

qunce
to
removal

noting
the

following

instructions

INSPECTION

Check
for

gas
leakage
as
follows

I

Plug
high
and
low

pressure
joints

on

compressor
with
blind

caps

2

Connect

charging
hoses
in
lines

between
manifold

gauge
and

high
and

low

pressure
service
valves

Connect

refrigerant
can

to
middle

hose
of

manifold

gauge

3

Open
valve
of
can

tap
and

charge

refrigerant
Loosen
oil
filler

plug
at

side
of

compressor
to

purge
air
out
of

compressor

4
Turn
shaft
5

or
6

turns
Then

confirm
that

pressure
does

not

decrease
on

low

pressure
gauge
If

gauge
indicates
a

pressure
decrease

there
is
a
leak

Conduct
a
leak
test

Under
such
a

condition
remove
and

then

install

parts
again

CYLINDER
HEAD

AND
VALVES

Insufficient

refrigerant
compression

is

likely
to
be
caused

by

damaged
head

gasket
or

damaged
valves

Prior

to

servicing
the
head
and
valve

plate
both
service

valves
should
be

opened
to
free

any
gas

pressure
which

may
be
in

the

compressor

REMOVAL

I

Remove
the
bolts

from

flanged

type
service

valves

using
Torx
Driver

Bit

Note
The
direction
of

flanged
type

service
valves

should
be
noted
for

reinstallation

AC812

Fig
AC
66

Removing
service
valves

2
Remove
the

remaining
bolts
in

the
head
Air

Conditioning

AC813

Fig
A
C
6
7
Removing

cylinder
head

bolts

3
Remove

valve

plate
and
head

from

cylinder
by
prying
or

tapping

under
the
ears
which
extend
from

valve

plate

If
head
and
valve

plate
adhere
hold

head
and

tap
valve

plate
ears

away

from

head
with
a

soft
hammer

Note
Do

not
hit
or

tap
head
to

separate
head
and
valve

plate
be

3use

damage
to
head

may
result

Fig
AC
68
Removing
valve

plate

and
head

4
When

removing
the

gaskets
use
a

sharp
edged
knife

Notes

a
In

removing
head

gasket
be

very

careful
not
to

damage
machined

sealing
surface

b
Do

not
reuse

gaskets

AC815

Fig
A
C
69
Removing
gasket

AC37
INSTALLATION

Valves
and
valve

plates
are
furnish

ed

only
as
a

complete
assembly

I

Apply
a
thin

film
of
clean

refrig

eration

oil
on
area
of
crankcase
to
be

covered

by
cylinder
gasket

2
Place

cylinder
gasket
in

position

on

cylinder
so
dowel

pins
in
crankcase

go
through
dowel

pin
holes
in

cylinder

gasket

3

Apply
a
thin

film
of
clean

refrig

eration

oil
to

top
and
bottom
valve

plate
areas
to
be
covered

by
gaskets

AC816

Fig
A
C
70
Applying
clean

refrigeration
oil

4
Place
valve

plate
in

position
on

cylinder

gasket
so

discharge
valve
as

semblies
i

e
smaller
diameter
assem

blies
with
restrainer

over
valve
reed

are

facing
up
and

locating
dowel

pins

go
through
dowel

pin
holes
in
valve

plate

Fig
A
C
71
Placing
valve

plate