JAC J2 - Page 80



Maintenance Manual for J2 Sedan
Mechanical Part of Engine
79
piston diam
eter should
be mea
sured at the positio
n shown in Figure
.
c.
Calculate
the
boring
size
based
on
the
piston
diameter.
[Boring size]
＝

[outer diameter
of
piston]
＋

[clearance between
piston and
cylinder (0.02-0.0
4mm)]
－

[grinding
margin
(0.02mm)]
d.
Boring each
cylinder till
it
obtains
the
calculated
boring
size.
Attention:
■ To avoid the distortion due
to
heat
during the
boring course, bore
the cylinders in following
sequence
: Cylinder 2 →
Cylinder 4 → Cylinder 1 →
Cylinder 3
e. Grind the cylinder till it
meets
the final
processing size
(outer diameter
of
piston
＋
 clearance
between piston and cylinder)
⑩

Diameter of Main Crankshaft Journal
Measure the main crankshaft journal by the outside micrometer.
Standard value: 48.0mm
If it exceeds the standard, please follow the rules of selection to replace.
⑪

Diameter of Main Journal of Connecting Rod
Measure the diameter of main journal of
connecting rod by using outside micrometer.
Standard values:43.0mm
Replace the connecting rod bearing shell if
measurement exceeds standard value.
⑫

Gap of Connecting Rod Bearing Shell
Note: Use
the
plastic
divider
to
perform
the
measurement.
a.
Clean
any
engine
oil
from
the
connecting
rod
journal and
connect
ing rod bear
ing shell.
b.
Put
the
plastic
divider
on
the
connecting
rod
journal,
and
asset
it
to
a
length
equal
to
bearing shell width. The plastic divider must
be placed at the center of connecting rod
journal
and
be parallel
with
the axial line of
connectin
g
rod.
c.
Lightl
y
put
the
connecting
rod
cover
to
specified place, and screw the bolt to
specified torque.
d.
Dismount the
bolt,
then
take
off the connecting rod
cover
slowly.
e.
Measure the
pressed portion of
plastic divider
at the
widest point
by the
scale which
is printed
on
the plastic divider bag.
Fig.1.1.066
Fig.1.1.065
Dial Indicator
