GM 12587310
Exhaust Manifold

The vehicle requires support during elevation while you remove the nuts that connect the Catalytic Converter to the left Exhaust Manifold. Lower the vehicle then remove spark plugs from their location. The heat shield bolts then the shield from the Exhaust Manifold must be removed prior to taking out the Exhaust Manifold bolts and the manifold itself. Discard the old gasket. Exhaust Manifold needs both cleaning steps and an inspection process. Make sure to check the threads in the Exhaust Manifold bolt holes on the Cylinder Head for clean condition without any presence of threadlocking materials or debris. Threadlock gm p/n 12345493 (Canadian P/N 10953488) should be applied as a 5 mm (0.2 inch) wide band to the Exhaust Manifold bolts' threads while keeping sealant off the initial 3 threads. Windward 12345493 (Canadian 10953488) as threadlocker on the bolts before installing the gasket and new bolts at 15 nm (11 ft. Lbs.) while beginning with the middle two bolts and proceeding with alternate side-to-side torques before finishing with 25 nm (18 ft. Lbs.) torques. Fit the heat shield followed by the bolts which should be torqued to 9 nm with an 80 inch lb torque setting then use a flat punch to fold over the Exhaust Manifold gasket at the rear of the left Cylinder Head. After reinstalling the spark plugs you should raise the vehicle to attach the Catalytic Converter securely to the left Exhaust Manifold by tightening its nuts to 50 nm (37 ft. Lbs.).

Start by placing a new exhaust manifold gasket and then install the exhaust manifold.

They should be clean and free of debris or threadlocking material.

Install a new exhaust manifold gasket.