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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 161 (Engine Mechanical - 4.8L, 5.3L, 6.0L And 6.2L (4 Of 5)) >> Off-Vehicle Repair Instructions (2 Of 3) >> Exhaust Manifold Cleaning and Inspection

Exhaust Manifold Cleaning and Inspection

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    Fig 1: View Of Exhaust Manifold & Heat Shield
    GM1401959Courtesy 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.
  1. Clean the exhaust manifold (600) and heat shield (603) in solvent.
    2. CAUTION: Refer to Safety Glasses Caution in Cautions and Notices.
  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 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.

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