Measuring Piston Ring Groove; Measuring Piston Ring End Gap - Mitsubishi Heavy Industries SL Series Service Manual

INSPECTION AND REPAIR OF BASIC ENGINE

4.3 Measuring piston ring groove

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.
Item
No.1
compression ring
Clearance
between
No.2
piston ring
compression ring
and ring
groove
Oil ring

4.4 Measuring piston ring end gap

(a) When replacing rings without boring (honing),
measure the end gap at the bottom of the cylinder
where the wear is minimum.
(b) When replacing the ring, use the ring of the same
size as the piston.
Insert the piston ring into the cylinder bore and push it with
the piston to achieve squareness. Then measure the end gap
with feeler gauges. Replace the piston ring if the limit is
exceeded.
Item
No.1
compression ring
Piston ring No.2
end gap compression ring
Oil ring
6-12
Standard Limit
0.09 to 0.11 mm 0.30 mm
[0.0035 to 0.0043 in.] [0.0118 in.]
0.07 to 0.11 mm 0.20 mm
[0.0028 to 0.0043 in.] [0.0079 in.]
0.03 to 0.07 mm 0.20 mm
[0.0012 to 0.0028 in.] [0.0079 in.]
Standard Limit
0.15 to 0.30 mm
[0.0059 to 0.0118 in.]
0.15 to 0.35 mm 1.50 mm
[0.0059 to 0.0138 in.] [0.0591 in.]
0.20 to 0.40 mm
[0.0079 to 0.0157 in.]
No.1 compression ring
Measuring piston ring groove
Thickness gauge
Measuring piston ring end gap
No.2 compression ring