Special service tools required:
Reamer set KM-515, reamer set KM-664, reamer set KM-805, reamer set KM-831, reamer set KM-961, reamer set KM-6022.
Measure
Preconditions: The valve guide and valve are measured. Valve stem play is determined. See "Valve stem play, determine".
Caution
Valve oversizes may already be fitted in production.
Inspect
Oversize identification:
Markings (code numbers/letters) are located on valve guide and valve stem end.
The oversize identifications (1) can be found in the "Technical Data".
Survey of relevant reamers:
| Valve guide diameter in mm | 5 mm | 6 mm | 7 mm | 8 mm |
|---|---|---|---|---|
| 0.012 | KM-6022 | |||
| 0.053 | KM-831-1 | |||
| X 25 DT only | ||||
| 0.068 | KM-831-2 | |||
| X 25 DT only | ||||
| 0.075 | KM-961 | KM-805 | KM-664-1 | KM-515-1 |
| 0.150 | KM-664-2 | KM-515-2 | ||
| 0.250 | KM-515-3 |
Caution
Reamers have a left-hand twist and must always be screwed both in and out clockwise. Never turn the reamers backwards (anti-clockwise). The shavings produced during material removal would become trapped and destroy the cutting edges.
Procedure
Ream valve guide from upper side of cylinder head to next oversize.
Screw reamer evenly into the valve guide exerting light pressure. Visually inspect the valve guide after reaming (chatter marks). The old identification must be obliterated (if present), and a new identification must be embossed.
Clean
Residual material must be removed from the valve guides and cylinder head after working.
