ing
be
red
ice
the
rn,
ore
or
lin-
ing
the
air,
ler)
Ig
(3) Clean the water jackets
of
the cylinder
block, removing water scales and rust,
if
any.
(4)
Check each cylinder bore for wear and
inspect the bore wall for scoring, scuffing
and
other
types
of
surface flaw,
to
deter-
mine whether repair by reboring
or
honing
is
necessary
or
not.
To
take micrometer
readings for wear determination, be sure
to
measure
at
three levels, I, 2 and 3, in two
directions, A and
B,
as
shown, thereby
producing a total
of
six readings.
(5)
If
the piston rings are
the
only parts
to
be
renewed, there being
no
need
of
reboring
or honing the cylinder bores, check the
amount
of
"ridge" formed
of
the top
portion
of
the bore and,
as
necessary,
remove the ridge by reaming. The bore
should be honed after this reaming.
Measuring cylinder bore diameter
Pistons, piston pins and piston rings
(1)
Burnt, grooved
or
badly scuffed pistons
must be replaced.
(2) Measure
the
piston diameter
at
its skirt in
the direction perpendicular
to
the piston
pin
to
determine its radial clearance in the
cylinder.
If
the
piston
is found excessively
worn, replace it.
ENGINE
Measuring
the
piston outside diameter
(3)
Check the side clearance
of
each ring in
the groove and,
as
neceSS31Y,
replace the
ring.
To
measure the side clearance
of
No. I ring,
which
is
taper, hold
the
ring face flush with
the land face, and insert a feeler gauge
between the piston and the
bottom
(flat)
side
of
the ring.
O~O,2
mm
(O~O,008
In)
Empty
weight
of
ring
Checking ring side clearance
(4) Piston rings whose
joint
gap
is
too large
must be replaced.
To
check the gap, place
the ring in the cylinder bore and push
it
down with the piston inserted upside down.
2-19
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