GM 12638991
Exhaust Manifold, Driver Side

The powertrain must be removed before starting the left Exhaust Manifold replacement. The pipe attachment to the bell housing relies on a manifold and Catalytic Converter assembly bolt for holding power. Users should first eliminate the connector position assurance (CPA) lock on the oxygen sensors before removing the Oxygen Sensor electrical connectors (1, 2). One must exercise precaution while dealing with Oxygen Sensor procedures. Start by removing the oxygen sensors from their position after which remove the left Exhaust Manifold heat shield bolts alongside the heat shield itself. First remove the bolts and nuts that secure the Exhaust Manifold before taking out the manifold itself along with the left Exhaust Manifold Gasket which should be disposed. The installation requires clean threads inside Exhaust Manifold holes of the Cylinder Head which must be free from debris and threadlocking substances. Embed a 5 mm (0.2 in) width threadlock gm p/n 12345493 (Canadian P/N 10953489) adhesive material along the threads of the Exhaust Manifold bolts and studs. Position the Exhaust Manifold along with its new gasket in its correct position. Extreme care must be taken because of fastener safety concerns. Start by installing the center Exhaust Manifold bolts and nuts first before moving toward the outer hardware while alternating the bolt direction from one side to the other. Tighten all hardware to 25 nm (18 lb ft). Position the Exhaust Manifold Catalytic Converter hanger bolt to the bell housing before tightening it to 50 nm (37 lb ft). Install the left Exhaust Manifold heat shield followed by its bolts while tightening each bolt to 10 nm (89 lb in). The threads of the oxygen sensors require application of anti-seize compound gm p/n 12377953 or equivalent before installation. When mounting sensors apply 42 nm (30 lb ft) force to the threads. Connect the Oxygen Sensor electrical wires while using cpa locks for installation. Finally, reinstall the powertrain.

Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493 or equivalent.

Connect the oxygen sensor electrical connectors and install the CPA locks.

Apply anti-sieze compound GM P/N 12377953 or equivalent.

First, remove the powertrain and the bolt securing the catalytic converter pipe to the bell housing.