Exhaust Manifold: Service and Repair

Exhaust Manifold Replacement (L61)

Removal Procedure

Notice: The oxygen sensor uses a permanently attached pigtail and connector. Do not remove the pigtail from the oxygen sensor. Damage to or removal of the pigtail connector could affect proper operation of the oxygen sensor.

Notice: The use of excessive force may damage the threads in the exhaust manifold/pipe.

Important: The in-line connector and louvered end must be kept clear of grease, dirt or other contaminants. Avoid using cleaning solvents of any type. DO NOT drop or roughly handle the HO2S.

Important: The HO2S may be difficult to remove when the engine temperature is less than 48°C (120°F)




1. Remove the connector position assurance (CPA) retainer (1).
2. Disconnect the engine wiring harness electrical connector (4) from the heated oxygen sensor (HO2S) electrical connector (3).
3. Remove the HO2S electrical connector rosebud clip (2) from the thermostat housing.




4. Remove the HO2S (1).




5. Remove the fuel feed pipe clips (2) from the fuel feed pipe bracket.




6. Remove the exhaust manifold heat shield bolts (2).
7. Remove the fuel feed pipe bracket (1).
8. Remove the exhaust manifold heat shield.




9. Remove the exhaust manifold pipe.
10. Remove the upper exhaust manifold brace bolt.




11. Remove and discard the exhaust manifold nuts.
12. Remove the exhaust manifold/catalytic converter assembly.
13. Remove and discard the exhaust manifold gasket.

Installation Procedure




1. Install a NEW exhaust manifold gasket on the studs.
2. Install the exhaust manifold/catalytic converter assembly.
3. Install the NEW exhaust manifold nuts finger tight.





Notice: Refer to Fastener Notice.

4. Install the upper exhaust manifold brace bolt.

Tighten the bolt to 25 N.m (18 lb ft).




5. Tighten the exhaust manifold nuts in the sequence shown.

Tighten the nuts to 14 N.m (10 lb ft).

6. Install the exhaust manifold pipe.




7. Position the exhaust manifold heat shield.
8. Position the fuel feed pipe bracket (1).
9. Install the exhaust manifold heat shield bolts.

Tighten the bolts to 23 N.m (17 lb ft).




10. Install the fuel feed pipe clips (2) to the fuel feed pipe bracket.





Important: A special anti-seize compound is used on the HO2S threads. The compound consists of graphite suspended in fluid and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or service sensors will already have the compound applied to the threads. If a sensor is removed from an engine and is to be reinstalled, the threads must have anti-seize compound applied before the reinstallation.

11. Coat the threads of the HO2S with anti-seize compound GM P/N 12377953 or equivalent, if necessary.
12. Install the HO2S.

Tighten the sensor to 42 N.m (31 lb ft).




13. Connect the engine wiring harness electrical connector (4) to the HO2S electrical connector (3).
14. Install the HO2S electrical connector rosebud clip (2) to the thermostat housing.
15. Install the CPA retainer (1).