Exhaust Manifold Cleaning and Inspection L98

Important: Do not use the exhaust manifold-to-cylinder head gaskets again. Upon installation of the exhaust manifold, install a NEW gasket. An incorrectly installed gasket or leaking exhaust system may effect on-board diagnostics (OBD)  II system performance.

1. Clean the exhaust manifold and heat shield in solvent.

Caution: Refer to Safety Glasses Caution in the Preface section.

2. Dry the exhaust manifold with compressed air.
3. Visually inspect the exhaust manifolds for the following conditions:

•	Damage to the gasket sealing surfaces.

•	Distortion of exhaust manifold mating surface.

•	Damage to the exhaust mounting holes.




4. Check for distortion on the mating surface of the exhaust manifold (3) by using a straight edge (1) and a feeler gauge (2).

An exhaust manifold deck with warpage in excess of 0.25 mm (0.01 in) within the 2 front or 2 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.

Exhaust Manifold Cleaning and Inspection LS2

Notice: Refer to Exhaust Service Caution in the Preface section.

1. Before installation inspect for the following:

•	Damage to the gasket sealing surfaces.

•	Distortion of exhaust manifold mating surface.

•	Damage to the exhaust mounting holes.




2. Check for distortion on the mating surface of the exhaust manifold (1) by using a straight edge (2) and a feeler gauge (3).

An exhaust manifold deck with warpage in excess of 0.25 mm (0.01 in) within the 2 front or 2 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.

3. Clean the exhaust manifold and catalytic converter flange mating surfaces.