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Home >> GMC >> 2003 >> Yukon Denali >> Repair and Diagnosis >> External Pages >> Different car >> Section 521 (Engine Mechanical (Repair Instructions -- 2 Of 3) -- 4.8L, 5.3L & 6.0L) >> Repair Instructions (Off-Vehicle - Part 2) >> Exhaust Manifold Cleaning and Inspection

Exhaust Manifold Cleaning and Inspection

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    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. 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 or damaged heat shield (603).
  5. Inspect the take down studs for damaged threads.
    6. Fig 1: View Of Manifold, Heat Shield & Bolts
    GM1277089Courtesy 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.

    7. Fig 2: Measuring Exhaust Manifold To Cylinder Head Surface For Warpage
    GM66607Courtesy of GENERAL MOTORS CORP.
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