Exhaust Manifold: Service and Repair

Exhaust Manifold Replacement (4.2L Engine)

Removal Procedure





1. Remove the air cleaner resonator outlet duct.
2. Remove the transmission filler tube stud nut from the A.I.R. adapter and move filler tube out of the way.
3. Remove the oil level indicator tube.
4. Remove the oxygen sensor from the exhaust manifold.





5. Remove 4 manifold heat shield nuts and remove the heat shield.
6. Raise the vehicle.





7. Loosen and remove the exhaust pipe bolts from the exhaust manifold.
8. Lower vehicle.





9. Loosen and remove the exhaust manifold bolts.
10. Remove the exhaust manifold.
11. Remove the exhaust manifold gasket.

Installation Procedure





1. Install a new exhaust manifold gasket.





2. Install the exhaust manifold.

Notice: Refer to Fastener Notice in Service Precautions.

3. With threadlock GM P/N 12345493 (Canadian P/N 10953488) on the manifold bolts, install the bolts onto the manifold.
3.1 Tighten the exhaust manifold bolts first pass in sequence to 25 Nm (18 ft. lbs.).
3.2 Tighten the exhaust manifold bolts second pass in sequence to 25 Nm (18 ft. lbs.).
3.3 Tighten the exhaust manifold bolts final pass in sequence to 25 Nm (18 ft. lbs.).





4. Install the exhaust manifold heat shield studs, if required.
^ Tighten the heat shield studs to 10 Nm (89 inch lbs.).
5. Install the oxygen sensor.





6. Install the exhaust manifold heat shield.
7. Add anti-seize compound GM P/N 12371386 to the exhaust manifold heat shield nuts.
8. Install the exhaust manifold heat shield nuts.
^ Tighten the exhaust manifold heat shield nuts to 5 Nm (44 inch lbs.).
9. Raise the vehicle.





10. Install the exhaust pipe to the manifold with seal and secure the pipe with the nuts.
^ Tighten the exhaust pipe nuts to 50 Nm (37 ft. lbs.).
11. Lower the vehicle.
12. Install the oil level indicator tube.





13. Move the transmission filler tube back onto the A.I.R. adapter block stud and secure the tube with a nut.
^ Tighten the transmission filler tube bracket nut to 10 Nm (89 inch lbs.).
14. Install the air cleaner resonator outlet duct.