Cylinder Head Ceramic Liners - Cracks or Breaks

9222porsche01

June 8, 1990


Model
911C2/C4


Group
1


Number
9015


Part Identifier
1570


Subject:
Cylinder Head Ceramic Liners





ATTENTION:
Service Manager/Service Technician

Models Affected:
911 Carrera 2 and 911 Carrera 4

Concern:
Cracks or breaks in ceramic exhaust port liners.

Repair Information:
Small cracks and/or breaks in the ceramic port liners in the area of the valve guides are sometimes visible even on new cylinder heads (See Figure 1). They do not influence the function of the port liners.

Cylinder heads must not be replaced for the above mentioned symptoms unless 1) breaks go down to the base material of the cylinder head, 2) broken surface area is larger than 1 sq.cm (0.155 sq.in.) or 3) the cracks extend from valve guide to the edge of the ceramic liner (on the valve seat or exhaust flange area).