CYLINDER
BLOCK
INSPECTION
AND
PISTON
CLEARANCE
NUMBERS
INDICATE
THE
SUGGESTED
ORDER
OF
DISASSEMBLY
2DDWEL--_
6
STIJIlS
"01·
n/
.
8
KNOCK
BUSHINGS
6 X
9~
CRINDER
BLOCK
INSPECTION
1. Before inspecting, clean the cylinder block to ensure that
the water and oil holes are not plugged.
If
clogged, clear
with compressed air.
2. Check for cracks and damage.
Use
a flaw detecting com-
pound as needed. Replace the block
if
defective.
3. Inspect the mating surface.
Using a straight edge and
feeler gauge measure the flatness
of
the top surface.
Grind or replace
if
the limit is exceeded.
FLATNESS
STANDARD
VALUE:
0.0020
in
(0.05
mm)
LIMIT:
0.004
in
(0.1
mm)
4. Inspect the cylinder bore. Using a cylinder gauge, mea-
sure the bore at six places (as shown in the diagram).
Calculate the difference between the max. and min.
val-
ues.
If
worn or damaged, rebore
or
replace the cylinder.
CYLINDRICITY
STANDARD
VALUE:
0.0004
in
(0.01
mm)
or
less
CYLINDER
BORE:
2.5591
-
2.5602
in
(65.00
-
65.03
mm)
UPPER
~f+------l~~
CENTER
MEASURING
DIRECTION
MEASURING
POSITION
LOWER
CHECKING
THE
PISTON
CLEARANCE
Calculate the difference between the minimum cylinder bore
in the thrust direction and the piston outer diameter shown in
. the illustration.
If
the difference exceeds the specified range,
replace the piston or cylinder
blo,?k,
or
rebore the cylinder.
PISTON
TO
CYLINDER
CLEARANCE
STANDARD:
0.0008
-
0.0016
in
(0.0
-
0.04
mm)
1"1
SEALING
CAPS
(35)
BORING
THE
CRINDER
1. Select an oversize piston based on the cylinder with the
maximum bore and maximum damage depth.
2.
Using the outer diameter (at the specified measurement
point)
of
the selected oversize piston, calculate the boring
dimension.
Boring
dimension
=
(Piston
0.0.) +
(piston
clearance)
-
(honing
margin:
0.0008in
(0.02mm))
OVERSIZE
PISTON
OUTSIDE
DIAMETER
AND
CYLINDER
(INNER
DIAMETER
FINISH
DIMENSION
(REF))
Size
Mark
Piston
Dia.
Cylinder
Inner
Dia.
0.250.S.
25
2.5677
-
2.5689in
2.5693
-
2.5697in
(65.22
-
65.25mm)
(65.26
-
65.27mm)
0.500.S.
50
2.5776
-
2.5787in
2.5791
-
2.5795in
(65.47
-
65.50mm)
(65.51
-
65.52mm)
0.750.S.
75
2.5874
-
2.58861n
2.5890
-
2.5894in
(65.72
-
65.75mm)
(65.76
-
65.77mm)
1.000.S.
100
2.5972
-
2.5984in
2.5988
-
2.59921n
(65.97
-
66.00m)
(66.01
-
66.02mm)
3. Bore the cylinder to obtain the calculated dimensions.
4. Hone to finish the cylinder inner diameter.
S. Check again for cylindricity and piston clearance .
Engines & Generators
33
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