Inspection Procedure

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Inspect the manifold for the following conditions:
- Damaged gasket or sealing surfaces
- Loose threaded inserts or studs
- Debris or restrictions within the passages of the manifold
- Damaged or broken vacuum fittings
- Inspect the composite intake manifold assembly for cracks or other damage.

Fig 1: Inspecting Intake Manifold Cylinder Head Deck For Warpage

Courtesy of GENERAL MOTORS CORP.

Inspect the intake manifold cylinder head deck for warpage.
1. Locate a straight edge across the intake manifold cylinder head deck surface.
  Position the straight edge across a minimum of two runner port openings.
2. Insert a feeler gage between the intake manifold and the straight edge.
  An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area is warped and should be replaced.