Exhaust Manifold Clean And Inspect (Unit Repair)

IMPORTANT:  Do not reuse exhaust manifold-to-cylinder head gaskets. Upon installation of exhaust manifold, install a NEW gasket. An improperly installed gasket or leaking exhaust system may effect On-Board Diagnostics (OBD) II system performance.

IMPORTANT:  Remove oxygen sensor prior to cleaning manifold, do not submerge oxygen sensor in cleaning solvent.

1. Remove heated oxygen sensor from manifold.
2. Clean exhaust manifold in solvent.
   CAUTION: WEAR SAFETY GLASSES IN ORDER TO AVOID EYE DAMAGE.
   Fig 1: Removing Exhaust Manifold Heat Shield

   Courtesy of GENERAL MOTORS CORP.
3. Dry the exhaust manifold with compressed air.
4. Inspect heat shield for damage.
5. Use a straight edge and a feeler gauge and measure the exhaust manifold mounting face for warpage.
6. An exhaust manifold face with warpage in excess of 0.25 mm (0.010 in.), may cause an exhaust leak and may effect OBD II system performance. Exhaust manifolds not within specifications must be replaced.
   Fig 2: Measure The Exhaust Manifold Mounting Face For Warpage

   Courtesy of GENERAL MOTORS CORP.