GM 19418950
Exhaust Manifold

The right Torsion Bar removal step and heating Oxygen Sensor (HO2S) unplug at sensor pigtail must happen before beginning the Catalytic Converter replacement process. If necessary, remove the ho2s. Secure the Muffler to the Catalytic Converter by removing all nuts then slide the Muffler backward to create pipe flange clearance. The process starts by removing three nuts that connect the Catalytic Converter to the Exhaust Manifold followed by lowering the converter out of the vehicle. Remove the old Exhaust Manifold seal from the flange before installing a brand new seal. Place the Catalytic Converter in position next to the Exhaust Manifold before use the 3 nuts without torquing them. Secure the Catalytic Converter properly to its front studs using two Muffler nuts. First use your hands to tighten the Muffler nuts until they touch the metal flange and then apply torque to 45 n.m (33 lb ft). Tighten each Catalytic Converter nut to 50 n.m (37 lb ft). You need to replace and connect the ho2s sensor at the sensor pigtail before reinstalling the right Torsion Bar .

Tighten the exhaust manifold bolts in sequence to 20 N.m (15 lb ft) three times, ensuring proper torque.

Take out the exhaust manifold bolts and then remove the exhaust manifold along with the gasket, discarding the old gasket.

Apply threadlock GM P/N 12345493 (Canadian P/N 10953488).

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

Tighten the muffler nuts by hand until they contact the metal flange, then tighten them to 45 N.m (33 lb ft).