Surface Distortion

WARNING: This page is about a different car, the 2005 Infiniti QX56. However, it is still accessible from the selected car via links, so may be relevant.

Check the flatness of each exhaust manifold flange surface using suitable tools.
1. Flatness limit: 0.3 mm (0.012 in)
If measurement exceeds the limit, replace the exhaust manifold.

Fig 1: Checking Flatness Of Each Exhaust Manifold Flange Surface Using Suitable Tools
Courtesy of NISSAN MOTOR CO., U.S.A.