Inspection Of Pistons And Piston Rings - Yanmar BY Series Service Manual

Pistons and Cylinders
IMPORTANT
Do not allow the connecting rod to bump the
crankshaft journal during piston removal.
Damage to the bearing journal may result.
10. Push the piston and connecting rod out of the
cylinder. Use a wooden dowel against the
connecting rod if necessary.
Figure 5-47
11. Remove the wrist pin retaining rings
(Figure 5-47).
IMPORTANT
Pistons and wrist pins are matched. NEVER
mix parts.
12. Push out the wrist pin. Keep piston and
matched wrist pin together.
Figure 5-48
BY Service Manual
13. Use a piston ring expander (Figure 5-48, (1)) to
remove the piston rings, taking care not to
scratch the surface of the piston.
Inspection of Pistons and Piston
Rings
Figure 5-49
Note: Measure cylinder bore to ensure it is
within specifications before measuring
piston ring end gap. See Inspection of
Cylinder Block on page 5-66.
1. Insert each piston ring, one at a time, into the
cylinder. Use a piston with the piston rings
removed to slide the ring squarely into the
cylinder bore. Measure the end gap of each
piston ring (Figure 5-49).
Specifications
Inspection Item
Side
Clearance
Top Piston
Ring
End Gap
Side
Second
Clearance
Piston
Ring
End Gap
Side
Clearance
Oil Ring
End Gap
Piston-to-
Clearance
Cylinder
ENGINE
Standard Limit
0.12 - 0.16 mm
-
(0.005 - 0.006 in.)
0.20 - 0.35 mm
-
(0.008 - 0.014 in.)
0.07 - 0.11 mm
-
(0.003 - 0.004 in.)
0.30 - 0.45 mm
-
(0.012 - 0.018 in.)
Cannot be measured
0.15 mm
(0.006 in.)
5-37