Caution: If the piston is replaced with a new one, replace the piston, piston pin and snap rings as a set.
1. Using a micrometer, measure the outside diameter of the piston at 8 mm from the edge of the piston skirt (uncoated piston skirt area) in the direction of the stop.
Note: Standard piston outside diameter: 88.965-88.995mm.
2. Measure the diameter of the cylinder bore.
3. Calculate the clearance between the piston and the cylinder by subtracting the piston diameter from the cylinder diameter. If the resulting clearance exceeds the maximum permissible value, replace the piston or cylinder block.
Note:
- Standard clearance between piston and cylinder: 0.025-0.045 mm.
- Maximum permissible clearance between piston and cylinder: 0.066 mm.
4. Using a set of flat feeler gauges, measure the side clearance of the piston rings in the grooves around the circumference of the piston. If the measured clearance is not within the norm, replace the piston or piston ring.
Note:
Standard side clearance of piston rings in piston grooves:
- Upper compression ring: 0.04-0.08 mm.
- Second compression ring: 0.03-0.07 mm.
- Oil scraper ring: 0.04-0.12 mm.
Maximum permissible lateral clearance of piston rings in piston grooves:
- Upper compression ring: 0.12 mm.
- Second compression ring: 0.10 mm.
- Oil scraper ring: 0.17 mm.