Mitsubishi S3Q2, Руководство по обслуживанию

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INSPECTION AND REPAIR OF BASIC ENGINE
6-13
4. Inspecting and repairing piston, connecting rod, crankshaft and crankcase
4.1 Measuring piston outside diameter
Using a micrometer, measure the piston outside diameter at
the skirt perpendicular to the piston pins as shown in the
illustration.
The piston weight is stamped on the top of piston head.
Measuring piston outside diameter
Piston weight stamp location
4.2 Measuring piston ring groove
&$87,21
Remove carbon deposits from pistons and check the
entire circumference of the piston.
(1)
Remove deposits such as carbon from each ring groove.
(2)
Check each ring groove for wear or damage. If it is
worn or damaged, replace the piston with a new one.
(3)
Insert the piston ring into the piston ring groove. Apply
a straight edge and insert thickness gauges to measure
the clearance between ring and ring groove.
If the limit is exceeded, replace the piston ring with a
new one.
Measuring piston ring groove
Item Nominal Standard Limit
Piston
outside
diameter
STD
87.970 mm
[3.4634 in.]
87.955 to 87.985 mm
[3.4628 to 3.4640 in.]
87.770 mm
[3.4555 in.]
0.25 OS
88.220 mm
[3.4732 in.]
88.205 to 88.235 mm
[3.4726 to 3.4738 in.]
88.020 mm
[3.4653 in.]
0.50 OS
88.470 mm
[3.4831 in.]
88.455 to 88.485 mm
[3.4825 to 3.4837 in.]
88.270 mm
[3.4752 in.]
Weight difference per piston 5g [0.20 oz.] or less -
14 mm [0.55 in.]
Direction at
right angles
to piston pin
S3Q2 S3Q2-T
Engine front
Front
mark
Identification
mark B
Symbol
size
Piston
weight mark
Engine front
Front
mark
Identification
mark T
Symbol
size
Piston
weight mark
Item Standard Limit
Clearance
between
piston ring
and
ring groove
No.1
compression ring 0.060 to 0.100 mm
[0.0024 to 0.0039 in.]
0.200 mm
[0.0079 in.]
No.2
compression ring 0.045 to 0.080 mm
[0.0018 to 0.0031 in.]
0.150 mm
[0.0059 in.]
Oil ring
0.025 to 0.065 mm
[0.0010 to 0.0026 in.]
0.150 mm
[0.0059 in.]
No.1 compression ring
No.2 compression ring