INSPECTION / REPAIR
B-56prose procedurePISTON, PISTON RING, AND PISTON PIN
Piston
CAUTION
If the piston is replaced, the piston rings must also be replaced.
Piston inspection
- 1Inspect the outer circumferences of all pistons for seizure or scoring. Replace the piston if necessary.
- 2Measure the outer diameter of each piston at a right angle (90°) to the piston pin, 16.5 mm (0.650 in) below the oil ring land lower edge.
05U0BX-155
Piston diameter
Standard
Diameter mm (in)77.954—77.974 (3.0690—3.0698)
0.25 (0.010) oversize
Diameter mm (in)78.211—78.217 (3.0792—3.0794)
0.50 (0.020) oversize
Diameter mm (in)78.461—78.467 (3.0890—3.0892)
Piston-to-cylinder clearance
- 3Measure the piston-to-cylinder clearance.
05U0BX-156 - 4If the clearance exceeds the maximum, replace the piston or rebore the cylinders to fit oversize pistons.
| Specification | Value |
|---|---|
| Clearancestandard | 0.039—0.052 mm (0.0015—0.0020 in)mm |
| Maximummaximum | 0.15 mm (0.006 in)mm |
Clearancestandard
0.039—0.052 mm (0.0015—0.0020 in)mm
Maximummaximum
0.15 mm (0.006 in)mm
Piston and Piston Rings
Ring-to-ring land clearance
- 1Measure the piston ring to ring land clearance around the entire circumference using a new piston ring.
05U0BX-157
| Specification | Value |
|---|---|
| Clearance (Top and Second)standard | 0.03—0.07 mm (0.0012—0.0028 in)mm |
| Maximummaximum | 0.15 mm (0.006 in)mm |
Clearance (Top and Second)standard
0.03—0.07 mm (0.0012—0.0028 in)mm
Maximummaximum
0.15 mm (0.006 in)mm
Piston ring further actions
- 2If the clearance exceeds the maximum, replace the piston.
- 3Inspect the piston rings for damage, abnormal wear, or breakage. Replace the piston rings if necessary.
- 4Insert the piston ring into the cylinder by hand and use the piston to push it to the bottom of the ring travel.
05U0BX-287