Valve Guide: Service and Repair

Checking





1 Clean valve guide.
2 Measure bore by means of a plug gage or an internal measuring instrument 5 mm above bottom edge of valve guide.

If the not go end of plug gage can be easily and completely inserted, replace valve guide.


Renewing





3 Force-out valve guide by means of knock-out mandrel.
4 Check basic bore in cylinder head for score marks.
Normally dimensioned valve guides can be inserted without machining basic bore, if the specified overlap is still available (refer to step 6).






5 When using repair stage valve guides, press respective manual broach through basic bore in cylinder head.
Pressing of manual broach through basic bore can be performed on a column-type drilling machine or a hydraulic press. An important requirement is that the hand broach is inserted vertically in relation to base of cylinder head. The spindle of the columntype drilling machine or of the hydraulic press should be free of play.






6 Coat valve guides with tallow and press-in by means of knocking-in mandrel until the dimension between cylinder head parting surface and valve guide underside named on table has been attained.






7 Check tight fit of valve guide with cylinder head cooled down only.
Test pressure of tight fit 3500 N.






8 Check ID of valve guide with plug gage.
The go end should still slip in.
The not go end should merely touch.






9 Slide valve into valve guide.
If the valve can be slipped in with difficulty only or not at all. ream valve guide by means of reamer.

10 Machine (refinish) valve seats. Valve Seat