Tools Required

J 43181 Heater Line Quick Connect Release Tool

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the exhaust manifold pipe nuts.
3. Lower the vehicle.
4. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 4.8L, 5.3L and 6.0L.
5. Drain the coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
6. Using the J 43181 , remove the heater core hoses from the heater core. Position aside.
7. Remove the spark plug wires. Refer to Spark Plug Wire Replacement in Engine Controls - 4.8L, 5.3L and 6.0L.
8. Remove the oil level indicator tube. Refer to Oil Level Indicator and Tube Removal in Engine Mechanical - 4.8L, 5.3L and 6.0L.



9. Remove the exhaust manifold bolts, manifold, and manifold gasket.
10. Discard the gasket.



11. Remove the heat shield bolts (1), and shield (2) from the exhaust manifold (1).
12. Clean and inspect the exhaust manifold. Refer to Exhaust Manifold Cleaning and Inspection in Engine Mechanical - 4.8L, 5.3L and 6.0L.

Notice: Refer to Fastener Notice in the Preface section.




1. Install the heat shield (2), and bolts (1) to the exhaust manifold (1), if necessary.

Tighten
Tighten the bolts to 9 N·m (80 lb in).





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.

•	The cylinder head exhaust manifold bolt hole threads must be clean and free of debris or threadlocking material.

•	Do not apply sealant to the first three threads of the bolt.

2. 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.
3. Install the NEW manifold gasket, exhaust manifold, and bolts.

Tighten

1. Tighten the exhaust manifold bolts a first pass to 15 N·m (11 lb ft). Tighten the exhaust manifold bolts beginning with the center two bolts. Alternate from side-to-side, and work 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 two bolts. Alternate from side-to-side, and work toward the outside bolts.
4. Using a flat punch, bend over the exposed edge of the exhaust manifold gasket at the front of the right cylinder head.
5. Install the oil level indicator tube. Refer to Oil Level Indicator and Tube Removal in Engine Mechanical - 4.8L, 5.3L and 6.0L.
6. Install the spark plug wires.
7. Install the inlet heater hose. Refer to Heater Inlet Hose Replacement in Heating, Ventilation and Air Conditioning.
8. Install the outlet heater hose. Refer to Heater Outlet Hose Replacement in Heating, Ventilation and Air Conditioning.
9. Install the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls - 4.8L, 5.3L and 6.0L.
10. Raise the vehicle.



11. Install the exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 50 N·m (37 lb ft).

12. Lower the vehicle.
13. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.