Inspection After Removal

Cylinder Head Bolts Outer Diameter

Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between "d1" and "d2" exceeds the limit, replace them with a new one.
Limit ("d1"-"d2"): 0.15 mm (0.0059 in)
If reduction of outer diameter appears in a position other than "d2", use it as "d2" point.

Fig 1: Identifying Cylinder Head Bolts Outer Diameter
Courtesy of NISSAN MOTOR CO., U.S.A.

Cylinder Head Distortion

NOTE: When performing this inspection, cylinder block distortion should be also checked. Refer to "INSPECTION AFTER DISASSEMBLY ".

Wipe off engine oil and remove water scale (like deposit), gasket, sealant, carbon, etc. with a scraper.
CAUTION: Use utmost care not to allow gasket debris to enter passages for engine oil or water.
At each of several locations on bottom surface of cylinder head, measure the distortion in six directions using straightedge (A) and feeler gauge (B).
Limit: 0.1 mm (0.004 in)
- If it exceeds the limit, replace cylinder head.
  
  Fig 2: Measuring Cylinder Head Distortion
  Courtesy of NISSAN MOTOR CO., U.S.A.