Exhaust Manifold Cleaning and Inspection

Important: 

• Do not reuse the exhaust manifold-to-cylinder head gaskets. 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.
• Inspect the exhaust manifold for cracks near the mounting holes (1-5).
  Fig 1: Locating Exhaust Manifold Mounting Holes

  Courtesy of GENERAL MOTORS CORP.

1. Clean the exhaust manifold with solvent.
   CAUTION: Refer to SAFETY GLASSES CAUTION .
2. Dry the exhaust manifold with compressed air.
3. Clean the exhaust manifold mating surface.
4. Use a straight edge and a feeler gage and measure the exhaust manifold mounting face for warpage.

   Exhaust Manifold Maximum Warpage 

   0.70 mm (0.0276 in)

5. If the warpage is greater than the maximum, replace the exhaust manifold.
   Fig 2: Inspecting Exhaust Manifold Mating Surface

   Courtesy of GENERAL MOTORS CORP.