Checking Piston Wear
- Clean the removed pistons with solvent naphtha. To identify the dimensional group (punched on the piston crown), carbon deposits must be carefully removed, e.g. with a brass brush.
- Check the piston diameter -D- at the piston skirt using an external micrometer. The measurement -X- is made at 16 mm from the bottom edge of the skirt.
NOTE:
- The piston must be replaced if the wear limit is exceeded!
The maximum permissible wear at the specified measurement point is 100 $$m (= 0.1 mm). The piston must be replaced if this dimension is exceeded! The reference dimensions for the piston groups are to be taken from the following table.
NOTE:
- Original pistons from the Porsche spare parts catalogue are available in the dimension group X only.
- Note the different weight groups!
DIMENSION SPECIFICATION - PISTONS
| Dimensional group (mm) | 2.5L engine | 2.7L engine | 3.2L engine | Wear in mm |
|---|---|---|---|---|
| I | 85.468 - 85.486 | 85.468 - 85.486 | 92.968 - 92.986 | max. 0.1 |
| X | 85.478 - 85.486 | 85.478 - 85.486 | 92.978 - 92.986 | max. 0.1 |
| II | 85.478 - 85.496 | 85.478 - 85.496 | 92.978 - 92.996 | max. 0.1 |