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).

1. Clean the exhaust manifold with solvent.
   CAUTION: Refer to SAFETY GLASSES CAUTION .
2. Dry the exhaust manifold with compressed air.
   Fig 1: Inspecting Exhaust Manifold

   Courtesy of GENERAL MOTORS CORP.
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: Measuring Exhaust Manifold Mounting Face For Warpage

   Courtesy of GENERAL MOTORS CORP.