G18 Engine Camshaft And Camshaft Bearings; G18 Engine Cylinder Block Inspection And Overhaul; G18 Engine Pistons Checking/G18 Engine Connecting Rods Checking; G18 Engine Crankshaft Inspection And Overhaul - Datsun 510 series Workshop Manual

CAMSHAFT AND CAMSHAFT BEARINGS
Check the camshaft bearing and journals for
signs of
wear
Plastigage should be used
to
check the clearance between bear
ing and journal which should be 0 025 0 075
mm
O OOl
0 0030
in
The cylinder head
assembly
must
be renewed if the
wear
limit of 0
mm
0 0039 in is exceeded
Place the camshaft in V blocks and apply
a
dial
gauge
to
the
centre
journal
to
check the
amount
of camshaft bend
The
run
out
of the camshaft
must not
exceed 0 03
mm
0 0012
in It should be noted that the actual
run
out
will be half the
value indicated
on
the dial gauge when the camshaft is turned
one
full revolution Check the camshaft end play which should
be within 0 07 0 148
mm
0 0028 0 0058 in
Check the
earn
contacting surfaces of the valve rocker and
the
earn
heels of the camshaft Slight damage
can
be corrected
using
a
fine oil
stone
It is advisable
at
this
stage to check the
clearance of the rocker shaft and rocker bushes which should be
0 016 0 052
mm
0 0006 0 0020 in The parts
must
be renewed
if the
wear limit of 0 07
mm
0 0028 in is exceeded
CYLINDER BLOCK
Inspection
and Overhaul
Check the block for signs of cracks
or
flaws Measure the
joint face for distortion using
a
straight edge
and feeler
gauge
as
described for the L14
Ll6 and L18
engines
The surface
must be
reground
if the maximum limit of 0 10
mm
0 0039 in
is exceeded
Check the
cylinder
bores for
wear
out of round and
excessive taper Use
a
bore
gauge to
take
readings
at
the top
middle and bottom positions of the bore
as
previously described
The standard bore diameters
are
85 000
mm
0 035 0
mm
3 3 47 0 00140 in
with
a wear
limit of 0 2
mm
0 0079 in
Out of round and taper
must
not
exceed 0 02
mm
0 0008 in
If
any
of the bores
are worn or
in
excess
of the specified limi
t
then all bores
must
be rebored
at
the
same
time
Pistons
are
available in five oversizes and should be selected
in accordance with the
amount
of
wear
of the cylinder Refer
to
the instructions given for the Ll4 L16 and L18 engines and
select
pistons
from the table below
PISTON SIZE
Standard
250 5
500 5
750 S
1000 S
1250 S
OUTER DIAMETER
84 958 84 990
mm
3 3 45 3 3 46
in
85 220 85 240
mm
3 355 3 3 56 in
85 470 85 490
mm
3 3 65 3 3 66
in
85720 85 740
mm
3 3 75 3 3 76 in
85 970 85 990
mm
3 3 846 3 3 854
in
86 22086 240
mm
3 3 94 3 3 95 in
Cylinder liners
can
be fitted if the bores
areworn
beyond
the maximum limit Undersize liners
are
available
with
outer
diam
ters
of 89 091 89 126
mm
3 507 3 509 in and inner
diameters of 83 5 84 5
mm
3 287 3 3 27
in The liners are
an interference fit in the block and
must
be rebored after
fitting
PISTONS
Checking
Oteck the pistons for signs
of seizure and wear
measure
the side clearance of the
rings in the ring
grooves
and check the
piston ring
gaps
as
previously described for the L14 Ll6 and
Ll8
engines
Compare the
figures
obtained with those
given in
the tables
opposite
Side clearance in grooves
Top ring
Second
ring
Oil ring
Standard
0 04 0 08
mm
0 0016 0031 in
0 02 0 06
mm
0 0008 0 0024 in
0 02 0 06
mm
0 0008 0 0024 in
Limit
LO
mm
0 0039
in
LO
mm
0 0039 in
LO
mm
0 0039 in
Piston ring
gap
Top ring
Second
ring
Oil
ring
Top ring
Second ring
Oil
ring
Standard
0 3 5 0 5 5
mm
0 01
38 D 021 7 in
0 3 5
mm
0 0138 0 0197 in
0 3 5 55
mm
O o J38
0217 in
Limit
LO
mm 0 0394 in
LO
mm
0 0394 in
LO
mm
0 0394 in
Top ring
Second
ring
Oil ring
Measure the
outer
diameter of the gudgeon pin in relation
to
the hole diameter
in the
piston Compare
the
figures
obtained
with those
given
in Technical Data and
replace
the
piston
and
pin
if the
wear
limit is exceeded
CONNECTING RODS
Checking
Check the connecting rods for bends
or
twists
using a
suit
able connecting
rod
aligner
The maximum deviation should
not
exceed 0 05
mm
0 0020 in
per
100
mm
3 94 in
of rod
Straighten
or
replace
any
rod which does
not
comply with the
specified limit When renewing
a
rod make
sure
that the weight
difference between
new
and old rods in within 6
gr
212
oz
Install the
connecting
rods with
bearings
to the
correspond
ing crank
pins
and check that the end
play of the big ends is
between 0 100 246
mm
0 0043 0 0097 in Replace
the
appropriate
rod if the maximum limit of 0 3
mm
0 0118 in
is exceeded
CRANKSHAFT
Inspection
and Overhaul
Clean the crankshaft
thoroughly and check the journals
and crank pins for taper and
out
of round Use
a micrometer
to
measure
the journals and crankpins
at
the
positions shown in
Fig A 7 It will be necessary
to
regrind the crankshaft if the
specified limit of 0 03
mm
0 0012 in is exceeded and then
fit the
appropriate
undersize
bearings
Place the crankshaft in
V blocks
as
described for the L14 L16 and LIB
engines and
apply
a
dial gauge
to
the
centre
journal
to
check that the bend
limit of 0 05
mm 0 0020 in is
not
exceeded The actual bend
value will be half the reading obtained
on
the
gauge
Install the
crankshaft in the
cylinder
block and check the crankshaft end
float which should be 0 060 0 192
mm
0 00240 0076 in
Replace the centre shims if the specified figure is exceeded
Make
sure
that the main drive shaft
pilot bearing
at
the
rear
of
the crankshaft is
not
worn or
damaged in
any way
Remove the
bearing if necessary
using
the
special
tool ST49700000
as
shown in
Fig
A 8 Clean the
bearing hole oil the outer side of
the
new
bearing and
use a
drift
as
shown in Fig A 9
to
drive
it into the hole Insert 2 grams 0 07
oz of multi purpose
grease
into the hole
as
illustrated
Main bearing clearance
Check the main bearing clearances
as
described for the
Ll4 Ll6 and Ll8
engines
The
Plastigage
should be
placed
so
57