23. Piston, Connecting Rod, and Bearing Clean and Inspect

Piston, Connecting Rod, and Bearing Cleaning and Inspection




1. Inspect the piston.
2. Using a gasket scraper, remove the carbon from the top of the piston.




3. Using a groove cleaning tool or broken ring, clean the piston ring grooves.





Note: Do not use a wire brush.

4. Using a brush and solvent, thoroughly clean the piston.
5. Using a micrometer, measure the piston diameter at right angles to the piston pin hole, and at a point 12.6 mm (0.4961 in) from the piston head.

Standard piston diameter: 80.461-80.471 mm (3.1677-3.1681 in)

6. If the diameter is not as specified, replace the piston.
7. Inspect piston oil clearance.
8. Subtract the piston diameter measurement from the cylinder bore diameter measurement.

* Standard oil clearance: 0.029-0.052 mm (0.0011-0.0020 in)
* Maximum oil clearance: 0.09 mm (0.0035 in)

9. If the oil clearance is greater than the maximum, replace all the pistons. If necessary, replace the cylinder block.




10. Using a feeler gauge, measure the clearance between a new piston ring and the wall of the ring groove.
11. If the groove clearance is not as specified, replace the piston.




12. Using a piston, push the piston ring a little beyond the bottom of the ring travel, 50 mm (1.97 in) from the top of the cylinder block.




13. Using a feeler gauge, measure the end gap.
14. If the end gap is greater than the maximum, replace the piston ring. If the end gap is greater than the maximum, even with a new piston ring, replace the cylinder block.




15. Using a caliper gauge, measure the piston pin bore diameter.

Standard piston pin bore diameter: 20.006-20.015 mm (0.7876-0.7880 in)

16. If the diameter is not as specified, replace the piston.




17. Using a micrometer, measure the piston pin diameter in three places (a,b,c).

Standard piston pin diameter: 20.004-20.013 mm (0.7876-0.7879 in)

18. If the diameter is not as specified, replace the piston pin.




19. Using a caliper gauge, measure the connecting rod small end bore diameter.

Standard connecting rod small end bore diameter: 20.012-20.021 mm (0.7879-0.7882 in)

20. If the diameter is not as specified, replace the connecting rod.
21. Subtract the piston pin diameter measurement from the piston pin bore diameter measurement.

* Standard oil clearance: -0.001 to +0.005 mm (-0.00004 to +0.0002 in)
* Maximum oil clearance: 0.010 mm (0.0004 in)

22. If the oil clearance is greater than the maximum, replace the connecting rod. If necessary, replace the piston and piston pin as a set.
23. Subtract the piston pin diameter measurement from the connecting rod small end bore diameter measurement.

* Standard oil clearance: 0.00-0.011 mm (0.0002-0.0004 in)
* Maximum oil clearance: 0.014 mm (0.0006 in)

24. If the oil clearance is greater than the maximum, replace the connecting rod. If necessary, replace the connecting rod and piston pin as a set.




25. Using a connecting rod aligner and feeler gauge, check the connecting rod alignment.
26. Check for misalignment.

Maximum misalignment: 0.05 mm (0.0020 in) per 100 mm (3.94 in)

27. If the misalignment is greater than the maximum, replace the connecting rod.




28. Check for twist.

Maximum twist: 0.15 mm (0.0059 in) per 100 mm (3.94 in)

29. If the twist is greater than the maximum, replace the connecting rod.