Outer Diameter of Cylinder Head Bolts

WARNING: This page is about a different car, the 2003 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.

Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between d1 and d2 exceeds the limit, replace the bolts with new ones.
1. Limit (d1 - d2) :0.23 mm (0.0091 in) or less
If reduction of outer diameter appears in a position other than d2, use it as d2 point.

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