Yanmar 6LPA-STP2 Service Manual page 136

ENGINE
6. Subtract the piston diameter from the cylinder
bore diameter.
• Standard oil clearance: 0.145 to 0.165 mm
(0.0057 to 0.0065 in.)
• Maximum oil clearance: 0.215 mm (0.0084 in.)
If the measured oil clearance exceeds the
specified maximum, replace all six pistons and
bore all six cylinders. Replace the cylinder block
as needed.
Note: When using a new cylinder block, make
sure the number on the cylinder block
and the number on the pistons are the
same.
7. Measure the clearance of the piston ring.
No. 1 ring (top ring):
Install a new piston ring to the piston. Measure
the clearance (Figure 5-116, (1)) between the
piston ring and ring groove using a thickness
gauge.
Figure 5-116
Figure 5-116
• Standard clearance: 0.050 to 0.095 mm
(0.002 to 0.004 in.)
• Maximum clearance: 0.20 mm (0.008 in.)
If the measured clearance exceeds the specified
maximum, replace the piston.
No. 2 ring (second ring) and oil ring:
Measure the clearance between the new piston
ring and ring groove using a thickness gauge
(Figure 5-117).
5-56
• Standard clearance No. 2 ring:
0.060 to 0.100 mm (0.002 to 0.004 in.)
Figure 5-117
• Standard clearance of oil ring:
0.030 to 0.070 mm (0.001 to 0.003 in).
• Maximum clearance: 0.20 mm (0.008 in.)
If the measured clearance exceeds the specified
maximum, replace the piston.
8. Measure the piston ring end gap.
(a) Insert the piston ring in the cylinder.
(1)
(b) Press in the piston ring to a position 130 mm
(5.118 in.) (Figure 5-118, (1)) from the
cylinder block top surface
(Figure 5-118, (2)), using the piston.
Figure 5-118
0005039
© 2007 Yanmar Marine International
Figure 5-117
(1)
Figure 5-118
6LPA Service Manual
Cylinder Block
0005040
(2)
0005041