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Section 8-0il Pan, Oil Filter, and Oil Pump and Pressure Relief Valve
27
With
the engine at normal
operating
temperature
and operating
at
fast idle,
check
for
oil lea ks
past the
housing
gasket
or
around
t
he
center
bolt
gasket.
If
oil
leak"
s
past the
hou
sing
gasket,
check
the
housing
for
proper
seating.
If
oil
leaks
past the
center bolt
gasket,
check
the center bolt
for
proper
t
orque.
c. Oil Pump and Pressure Relief Valve
Remove
and disassemble
the
oil pump
and
pressure
relief
valve.
Wash
all parts in
a solvent and
dry them
thoroughly.
U
se
a brush to clean the
inside of
the
pump housing and the pressure relief
valve
bore.
B
e
s ure
all dirt
a
nd
c hips are
removed.
Rem
ove all
old
gasket material
from
the pump
body
an
d
cover.
Check
the pump
housing for
damage or excessive
wear. Check
the pump
gear
teeth for
damage or wear.
Check
the
compression of the relief valve spring.
Check
the
relief
valve clearance
in the relief
valve
bore.
Check the
driven shaft
cleara
nce.
Replace
a
ny
worn or defective parts.
9. CYLINDER BLOCK, PISTONS, PISTON RINGS, AND CONNECTING RODS
Procedures for
checking
the
cylinder
bloc
k; for
clea
n-
ing, inspecting,
and fitting pistons;
for
fitting piston
rings;
and
for
checking connecting rod
a
lignment
are
given
below.
a. Cylinder Block.
Make
a
thorough
check for cracks.
Minute
cracks
not
visible to the
naked
eye may be detected by coat-
ing the
suspected area with
a mixture
of
25
0/
0
kerosene
and 75%
light motor
oil.
Wipe
the part dry and im-
mediately
apply a coating of zinc
oxide
dissolved
in
wood
alcohol.
If
cracks are
present,
the
coating
will
become discolored
at
the
defective area.
Inspect the
cylinder bores
for
scores.
Check
the
cylinder
bore for taper,
out of
round,
and
wear. Use
a
cylinder
bore
gauge,
telescope
gauge, or
inside micro-
meters. Measuring the
cylinder with
a
cylinder bore
gauge
is
illustrated
in fig. 44. Only
experienced
person-
nel should be permitted
to
take
these measurements.
Rebore the
cylinder when
the
taper and
/
or
out-of-
roundness exceed
the
maximum
allowable
tol erances.
b. Pistons, Piston Pins, and Rings.
Before
removi
ng
a
piston
from the
engine,
remove
any
ridges that
may be present
along the upper part
of
each
cylinder as
follows:
Move the piston to the
bottom of its travel, and
place a cloth
on
the piston head to
collect the cuttings.
Remove the cylinder ridge
as shown
in fig. 45,
accord-
ing to the instructions furnished by the
manufacturer
of the ridge
cutter
being used.
CAUTION:
Never
cut
into the ring travel area in
excess
of
1/
32
inch wlren removing ridges.
Remove the ridge
cutter
from the
cylinder
bore.
Turn the
crankshaft
until the piston is
at the
top of
its
stroke
and
carefully remove the
cloth
with the
cuttings
from the piston h
ead. Remove the
pistons.
(1)
CLEANING
AND INSPECTION.
Clean
the
piston ring
grooves
with a
ring
groove
cleaner
(fig.
46).
Clean the piston
in solvent.
Do not
use a
ca ustic clean-
ing
solution.
Make
sure the oil ring slots
(or holes)
are
clean.
Inspec
t
pistons
for fractures
at
the
ring
lands, skirt,
and
pin
bosses.
Spongy,
eroded areas
near the
edge of
the piston top,
usua
ll
y
on the
side
opposite the valves,
are
ca used
by detonation, or pre-ignition.
Inspect
the piston pins
for
signs
of fracture
or etch-
ing.
Check
the pin
for
proper
fit
in the piston and
rod
bushi
n
g.
(2)
REPAIRS.
R eplace
pistons showing signs of
excessive skirt clearance, wavy
ring
lands,
fractures
or damage from detonation.
Replace
piston pins showing signs of
fracture
or
etching.
Piston pins
that show
wear
or
fit loosely in
the
piston
or rod bushing should
be replaced. Replace
all piston pin retainers.
(3) FITl'lNG PISTONS.
To fit
a
piston in the
cylinder
bore,
attach a
tension
scale
to the
end of a
feeler gauge
ribbon
which is
1
/2-inch wide
and
which
has
the
prope
r
thickness.
Position the feeler
on the
side of the piston 90
°
from the piston pin
hole.
In-
vert
the
piston,
then push the
piston
and
feel er into
the
bore
so the end of the
piston is
approximately
5f8-
inch
below
the
top
of the block.
Keep the piston pin
bore parallel
to
the
crankshaft
axis.
Hold
the
piston
and pull
out
the feeler ribbon,
noting the reading
on
the
pull scale (fig.
47).
If
the scale
reading
is
greater
than the
maximum
•
Fig. 44-Measuring Cylinder Bore
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