NOTE The intake manifold, throttle body, fuel injection rail, and fuel injectors may be removed as an assembly. If not servicing the individual components, remove the manifold as a complete assembly.
Fig. EVAP solenoid removal-4.8L, 5.3L and 6.0L engines
Remove or disconnect the following:
Positive Crankcase Ventilation (PCV) hose and valve Manifold Absolute Pressure (MAP) sensor, if required Engine coolant air bleed clamp and hose from the throttle body Knock sensor connector, if required. Accelerator control cable bracket and bolts, if required Fuel rail with injectors EVAP solenoid, bolt, and isolator Intake manifold bolts Intake manifold with gaskets Intake manifold-to-cylinder head gaskets from the manifold. Discard the intake manifold gaskets. Throttle body and gasket
Fig. Throttle body removal-4.8L, 5.3L and 6.0L engines
Clean the intake manifold in solvent.
Dry the intake manifold with compressed air.
Inspect the throttle body and wire harness studs and stud inserts for looseness or damaged threads.
Inspect the fuel rail bolt inserts for looseness or damaged threads.
Inspect the intake manifold vacuum passages for debris or restrictions.
Inspect for damaged or broken vacuum fittings, damaged MAP sensor mounting bore, or broken MAP sensor retaining tabs.
Inspect the composite intake manifold assembly for cracks or other damage.
Inspect the areas between the intake runners. Inspect all the gasket sealing surfaces for damage.
Inspect the fuel injector bores for excessive scoring or damage. Inspect the intake manifold cylinder head deck for warpage.
Locate a straight edge across the intake manifold cylinder head deck surface. Position the straight edge across a minimum of two runner port openings.
Insert a feeler gauge between the intake manifold and the straight edge. A intake manifold with warpage in excess of 0.118 in. (3mm) over a 7.87 in. (200mm) area is warped and should be replaced.
Install or connect the following:
MAP sensor EVAP solenoid, bolt, and isolator. Tighten the bolt to 89 inch lbs. (10 Nm). NEW intake manifold-to-cylinder head gaskets Intake manifold
Apply a 0.20 in. (5mm) band of threadlock GM P/N 12345382 or equivalent to the threads of the intake manifold bolts.
Intake manifold bolts. Tighten intake manifold bolts first pass in sequence to 44 inch lbs. (5 Nm). Tighten intake manifold bolts final pass in sequence to 89 inch lbs. (10 Nm). PCV valve and hose Coolant air bleed hose and clamp onto the throttle body Accelerator control cable bracket and bolts. Tighten the bolts to 89 inch lbs. (10 Nm).
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