Manual:HUMMER H3 Alpha 2010Page:00373319 / 37163

Exhaust Manifold Cleaning and Inspection

WARNING: This page is about a different variant/trim than selected.
    Fig 1: Exhaust Manifold, Heat Shield & Bolts
    GM1876567Courtesy of GENERAL MOTORS CORP.
    NOTE: 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 affect on-board diagnostics (OBD) II system performance.
  1. Clean the exhaust manifold (600) and heat shield (603) in solvent.
    2. WARNING: Refer to Safety Glasses Warning .
  2. Dry the exhaust manifold with compressed air.
  3. Inspect the exhaust manifold-to-cylinder head gasket surface for excessive scratches or gouging.
  4. Inspect for a loose, damaged, or cracked heat shield (603).
  5. Inspect the studs (605) for damaged threads.
    6. Fig 2: Measuring Exhaust Manifold To Cylinder Head Surface For Warpage
    GM66607Courtesy of GENERAL MOTORS CORP.
  6. Use a straight edge and a feeler gauge 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 2 front or 2 rear runners or 0.5 mm (0.02 in) overall, may cause an exhaust leak and may affect OBD II system performance. Exhaust manifolds not within specifications must be replaced.