During the service of 6.2L diesel cylinder heads, the observance of hairline cracks may be noted in the pre-chamber area.
Cracks on the face of the pre-chamber start at the edge of the fire slot. From the edge, the cracks proceed toward the circular impression of the head gasket bead.
These cracks are a form of stress relief and are completely harmless up to a length of 5mm (3/16″)- Cracks longer than this are approaching the head gasket sealing bead and should be replaced with the proper part number.
See Figure 3-8. This illustration of a pre-chamber displays both acceptable and nonacceptable cracks.
