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

Piston, Connecting Rod, and Bearings Cleaning and Inspection

Caution: Refer to Safety Glasses Caution in Service Precautions.

Important: Measurement of all the components should be taken with the components at room temperature. Do not use a wire brush in order to clean any part of the piston.





1. Clean the piston and connecting rod in cleaning solvent.
2. Dry the components with compressed air.





3. Clean the piston ring grooves with a suitable ring groove cleaning tool.





4. Clean the piston oil lubrication holes and slots.
5. Inspect the piston for the following:
^ Eroded areas (1) on the top of the piston
^ Scuffed or damaged skirt (2)
^ Damage to the piston pin bore (3)
^ Cracks in the piston ring lands, the piston skirt, or the piston pin bosses
^ Piston ring grooves for nicks, burrs, or other warpage, which may cause the piston ring to bind.
6. Inspect the piston pin for scoring, wear or other damage.





7. Measure the piston ring-to-piston ring groove side clearance.
7.1. Insert the edge of the piston ring into the piston ring groove.
7.2. Roll the piston ring completely around the piston.
^ If binding is caused by a distorted piston ring groove, MINOR imperfections may be removed with a fine file.
^ If binding is caused by a distorted piston ring, then replace the piston ring.





8. Measure the piston ring side clearance with a feeler gage.
^ If the piston ring side clearance is too small, try another piston ring set.
^ If the proper piston ring-to-piston ring groove clearance cannot be achieved, replace the piston and pin assembly.
9. To determine the proper piston ring side clearance, refer to Specifications.





10. Inspect the connecting rod for an out-of-round bearing bore.





11. Inspect the connecting rod for twisting.
12. Inspect the connecting rod for damage to the connecting rod bolt threads.





13. Measure the piston compression ring end gap.

Important: Fit each piston compression ring to the cylinder in which it will be used.

13.1. Place the piston compression ring into the cylinder bore.
13.2. Push the piston compression ring into the cylinder bore to approximately 6.5 mm (0.25 inch) above the piston ring travel.
The piston ring must be square to the cylinder wall.
13.3. Use a feeler gage in order to measure the piston ring end gap.
Select another size piston ring set if the piston ring end gap exceeds specifications.