Exhaust Manifold Cleaning and Inspection

WARNING: This page is about a different car, the 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 Chevrolet TrailBlazer, and 2004 Buick Rainier. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: View Of Manifold, Heat Shield & Bolts

Courtesy of GENERAL MOTORS CORP.

IMPORTANT: Do not use the exhaust manifold-to-cylinder head gaskets again. Upon installation of the exhaust manifold, install a NEW gasket. An improperly installed gasket or leaking exhaust system may effect On-Board Diagnostics (OBD) II system performance.

Clean the exhaust manifold (600) and heat shield (603) in solvent.
Dry the exhaust manifold with compressed air.
Inspect the exhaust manifold-to-cylinder head gasket surface for excessive scratches or gouging.
Inspect for a loose or damaged heat shield (603).
Inspect the take down studs for damaged threads.

Fig 2: Measuring Exhaust Manifold To Cylinder Head Surface For Warpage

Courtesy of GENERAL MOTORS CORP.

Use a straight edge and a feeler gage and measure the exhaust manifold cylinder head deck for warpage.
An exhaust manifold deck with warpage in excess of 0.25 mm (0.01 in) within the two front or two rear runners or 0.5 mm (0.02 in) overall, may cause an exhaust leak and may effect OBD II system performance. Exhaust manifolds not within specifications must be replaced.