Reworking Cylinder Head: Notes

1. Carefully clean the removed cylinder head (parts washing machine, solvent naphtha). Remove residual sealant from the sealing surface, e.g. with (commercially available) foil eraser or acetone.
2. Check sealing surface of cylinder head for distortion using a straight-edge.

   Permissible unevenness of the parting plane: 0.05 mm 

3. Cylinder heads with distorted sealing surface can be repaired by surface milling.
   NOTE:

   • The permissible peak-to-valley surface roughness for machining the sealing surface is 0.015 mm.
   • Rework sealing surface of the cylinder head only until a flat surface has been achieved.

Permissible unevenness of parting plane: 0.03 mm 

The permissible wear -X- for the cylinder head height is be taken from the following table. 

Fig 1: Measuring Cylinder Head Height "X"

Courtesy of PORSCHE OF NORTH AMERICA, INC.