1. Remove the engine sight cover Refer to Upper Intake Manifold Sight Shield Replacement in Engine Mechanical - 6.0L.
2. Remove the spark plugs. Refer to Spark Plug Replacement in Engine Controls - 6.0L.
3. Remove the bank 2, sensor 1 oxygen sensor. Refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 in Engine Controls - 6.0L.
4. Remove the oil level indicator and tube assembly. Refer to Oil Level Indicator and Tube Replacement in Engine Mechanical - 6.0L.
5. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
6. Remove the catalytic convertor. Refer to Catalytic Converter Replacement in Engine Exhaust.
7. Lower the vehicle.
8. Remove the mounting nuts for the exhaust manifold.




Important: In the following service procedure, it may be necessary to remove the heat shield from the exhaust manifold.

9. Remove the exhaust manifold and gasket.

Important: Tighten the exhaust manifold bolts as specified in the service procedure. Improperly installed and/or leaking exhaust manifold gaskets may affect vehicle emissions and/or On-Board Diagnostics (OBD) II system performance.

Notice: Refer to Fastener Notice in the Preface section.

1. If necessary, install the exhaust manifold heat shield and bolts.

Tighten
Tighten the exhaust manifold heat shield bolts to 9 N·m (80 lb in).

2. Raise the vehicle.

Important: In the following service procedure, DO NOT tighten the exhaust clamp. Leave it loosened so that the exhaust manifold and gasket can be aligned on the cylinder head.

3. Install the catalytic convertor on the intermediate pipe.
4. Lower the vessel.




Important: Use one or two bolts to hold the manifold and gasket in place.

5. Install the exhaust manifold and gasket.
6. Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493 (Canadian P/N 10953488) or equivalent to the threads of the exhaust manifold bolts.
7. Install the exhaust manifold bolts.

Tighten

1. Tighten the exhaust manifold bolts at first pass to 15 N·m (11 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side to side, working toward the outside bolts.
2. Tighten the exhaust manifold bolts a final pass to 25 N·m (18 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side to side, working toward the outside bolts.
8. Install the oil level indicator and tube assembly. Refer to Oil Level Indicator and Tube Removal in Engine Mechanical - 6.0L.
9. Install the spark plugs. Refer to Spark Plug Replacement in Engine Controls - 6.0L.
10. Install the engine sight cover Refer to Upper Intake Manifold Sight Shield Replacement in Engine Mechanical - 6.0L.
11. Install the bank 2, sensor 1 oxygen sensor. Refer to Catalytic Converter Replacement in Engine Controls - 6.0L.
12. Raise the vehicle.
13. Install the catalytic convertor to the exhaust manifold nuts.

Tighten
Tighten the exhaust manifold nuts to 20 N·m (15 lb ft).

14. Tighten the exhaust clamp for the catalytic convertor.

Tighten
Tighten the exhaust clamp to 20 N·m (15 lb ft).

15. Lower the vehicle.