Intake Manifold Cleaning and Inspection L98, LS2

1. Remove the fuel rail with injectors. Refer to Fuel Rail and Injectors Removal.
2. Remove the evaporative emission hoses/pipes. Refer to Evaporative Emission Hoses/Pipes Replacement - Engine.
3. Remove the evaporative emission (EVAP) canister vent solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
4. Remove the throttle body and gasket. Refer to Throttle Body Removal.
5. Clean the intake manifold in solvent.

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

6. Dry the intake manifold with compressed air.

1. Inspect the manifold for the following conditions:

•	Loose threaded inserts or studs.

•	Damaged gasket or sealing surfaces.

•	Damaged or broken vacuum fittings.

•	Debris or restrictions within the passages of the manifold.

•	Inspect the composite intake manifold assembly for cracks or other damage.

2. Inspect the intake manifold cylinder head deck for warpage.

2.1.	Locate a straight edge across the intake manifold cylinder head deck surface.

Position the straight edge across a minimum of two runner port openings.

2.2.	Insert a feeler gage between the intake manifold and the straight edge.

An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area is warped and should be replaced.

Intake Manifold Cleaning and Inspection LS3

1. Remove and discard the intake manifold-to-cylinder head gaskets (514).
2. Remove the manifold absolute pressure (MAP) sensor. Refer to Intake Manifold Removal.
3. Remove the evaporative emission (EVAP) canister purge solenoid valve, EVAP tubes, and fuel rail with injectors. Refer to Fuel Rail and Injectors Removal.
4. Remove the throttle body and gasket. Refer to Throttle Body Removal.
5. Clean the intake manifold in solvent.

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

6. Dry the intake manifold with compressed air.

1. Inspect the manifold for the following conditions:

•	Lose threaded inserts (1)

•	Damaged MAP sensor bore (2)

•	Damaged fuel injector bore (3)

•	Damaged gasket or sealing surfaces (4)

•	Damaged or broken vacuum fittings (5)

•	Debris or restrictions within the passages of the manifold

•	Inspect the composite intake manifold assembly for cracks or other damage.

2. Inspect the intake manifold cylinder head deck for warpage.

2.1.	Locate a straight edge across the intake manifold cylinder head deck surface.

Position the straight edge across a minimum of 2 runner port openings.

2.2.	Insert a feeler gage between the intake manifold and the straight edge.

An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area is warped and should be replaced.