Exhaust Manifold Replacement - Left Side

Exhaust Manifold Replacement - Left Side (LZ9) (3.9L)

Special Tools

J 39194-B Heated Oxygen Sensor Wrench

Removal Procedure




1. Remove the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement (Air Cleaner Outlet Duct Replacement).
2. Remove the connector position assurance (CPA) retainer (5).
3. Disconnect the heated oxygen sensor (HO2S) electrical connector (4).
4. Remove the HO2S clip (3) from the oil level indicator tube bracket.





Note: The HO2S uses a permanently attached pigtail and connector. This pigtail should not be removed from the sensor. Damage or removal of the pigtail or connector will affect proper operation of the sensor.

5. Remove the HO2S using the J 39194-B .




6. Remove the exhaust manifold heat shield bolts.
7. Remove the exhaust manifold heat shield.




8. Remove the upper exhaust manifold bolts.
9. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle (Service and Repair).
10. Remove the left catalytic converter. Refer to Catalytic Converter Replacement - Left Side (LY7) (Service and Repair)Catalytic Converter Replacement - Left Side (LZ4) (Service and Repair)Catalytic Converter Replacement - Left Side (LZ9) (Service and Repair).
11. Remove the lower exhaust manifold bolts.
12. Remove the exhaust manifold.
13. Remove and discard the exhaust manifold gasket.

Installation Procedure




1. Install a NEW exhaust manifold gasket onto the cylinder head studs.
2. Install the exhaust manifold.

Caution: Refer to Fastener Caution (Fastener Caution).

3. Install the exhaust manifold bolts.

Tighten the bolts to 20 Nm (15 lb ft).

4. Install the left catalytic converter. Refer to Catalytic Converter Replacement - Left Side (LY7) (Service and Repair)Catalytic Converter Replacement - Left Side (LZ4) (Service and Repair)Catalytic Converter Replacement - Left Side (LZ9) (Service and Repair).
5. Lower the vehicle.




6. Install the exhaust manifold heat shield.
7. Install the exhaust manifold heat shield bolts.

Tighten the bolts to 10 Nm (89 lb in).





Note: Whenever the oxygen sensor is removed, coat the threads with nickel-based anti-seize compound, such as GM P/N 5613695, or equivalent.

8. Install the HO2S using J 39194-B .

Tighten the sensor to 42 Nm (31 lb ft).




9. Connect the HO2S electrical connector (1).
10. Install the CPA retainer (2).
11. Install the HO2S clip (3) to the oil level indicator tube bracket.
12. Install the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement (Air Cleaner Outlet Duct Replacement).