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.
Scheme 770
Note. The piston must be replaced if the wear limit is exceeded!
The maximum permissible wear at the specified measurement point is 100 $$m (= 0.1 mm). The piston must be replaced if this dimension is exceeded! The reference dimensions for the piston groups are to be taken from the following table.
Note. Original pistons from the Porsche spare parts catalogue are available in the dimension group X only. Note the different weight groups!
| Dimensional group (mm) | 2.5L engine | 2.7L engine | 3.2L engine | Wear in mm |
|---|---|---|---|---|
| I | 85.468 - 85.486 | 85.468 - 85.486 | 92.968 - 92.986 | Max. 0.1 |
| X | 85.478 - 85.486 | 85.478 - 85.486 | 92.978 - 92.986 | Max. 0.1 |
| II | 85.478 - 85.496 | 85.478 - 85.496 | 92.978 - 92.996 | Max. 0.1 |
DIMENSION SPECIFICATION - PISTONS
Scheme 771
| Item | Designation | Explanation |
|---|---|---|
| A (1) | Shaft ($$ 20 x 450 mm) | Art. No. 6024515 |
| B (1) | Aluminum supports (1 pair) | Art. No. 6023620 |
| C (1) | Lever arm | Art. No. 6023530 |
| D (1) | Joint with screw | Art. No. 6024520 |
| E (1) | Magnetic disassembly head | Art. No. 6024650 |
| F (1) | Assembly head 1b for valve keys | Art. No. 6000102 |
| G (1) | Pressure piece 6e (3 ea.) | Art. No. 6006015 |
| H (1) | Pad for valve discs (3 ea.) | Art.-No. 6025665 (Items A to H) |
| I (1) | Screws for aluminum supports (4 ea.) | Commercially available, M6 x 40 |
| (1) For explanation see scheme 552 | ||
| (1) | For explanation see scheme 552 |
SPECIAL TOOLS (1 OF 2)
Scheme 772
| Item | Designation | Special tool | Explanation |
|---|---|---|---|
| A (1) | Extractor for valve stem seal | 3364 | VW special tool |
| B (1) | Press-on tool for valve stem seal | 3365 | VW special tool |
| C (1) | Pressure piece, for fitting the oil protection tubes | 9605 | |
| C1 (1) | Pressure piece, for fitting the oil protection tubes (engine installed) | 9605/1 | |
| D (1) | Hand pressure piece | 9604 | |
| E (1) | Tensioning screw for relieving the tensioning elements (VarioCam) | 9632 | Use tensioning screw 9632/1 as of engine number 65X19696. |
| (1) For explanation (Scheme 773) | |||
| (1) | For explanation (Scheme 773) |
SPECIAL TOOLS (1 OF 2)