GM 19419597
Catalytic Converter

In replacing the catalytic convertor of 6.0l and 8.1l engines one should begin by raising and supporting the vehicle, and then support the transmission by using a correct transmission jack. Remove the transmission mount to transmission support nuts, lift the transmission off of the support, take out the transmission support cross member bolts and the cross member. Depending on which side is to be replaced one removes (the exhaust muffler) nuts on the muffler, or loosens the exhaust pipe clamp. Remove the necessary exhaust system hangers to disengage the pipes and employ a jack stand to hold the exhaust in place. Pull off the connector position assurance (CPA) retainers and oxygen sensor electrical connectors (1, 2). Loosen the right nuts for the exhaust manifold pipes and remove the nuts for the left exhaust manifold pipes. Lower the transmission a little with the use of the transmission jack, take out the Catalytic Converter, and move its hanger out of the bracket of the exhaust pipe hanger. If you are carrying a 6.0l engine with regular production option (RPO) y91, then take the oxygen sensors when restorating the Catalytic Converter (chances are you may have to remove the Catalytic Converter again). When installing, apply anti-seize compound gm p/n 12377953 or type to the old oxygen sensors and install them, tightening them to 42 nm (31 ft. Lbs.). When the vehicle is either equipped with a 6.0l engine, and the engine is rpo y91, then if the exhaust seal is new, it must put that on the exhaust manifold and then the Catalytic Converter must be installed, doing so by sliding the hanger into the exhaust pipe hanger bracket. Restart the replacement of a new exhaust seal to the exhaust manifold and to the Catalytic Converter. Put the left exhaust manifold pipe nuts into place and tighten the right exhaust manifold pipe nuts to 50 nm (39 ft. Lbs.). Aerate the transmission slightly using transmission jack, reconnect oxygen sensor electrical connectors (1,2) and attach the cpa retainers. Mount the exhaust pipe/Catalytic Converter to the vehicle and the exhaust system hangars. Depending on the side being replaced either install the exhaust muffler nuts and tighten to 40nm (30ft. Lbs.), or install a new exhaust pipe clamp and tighten to 44nm (33ft. Lbs.). Reinstall the transmission support coss memberand the bolts tight 95 nm (70 ft. Lbs.), lower the transmission on the support, and install the transmission mount to transmission support nuts, tight 40 nm (30 ft. Lbs.). Lastly, take off the support from the transmission, and lower the car.

The procedure to replace the left Catalytic Converter on a 6.0l cab/chassis begins by raising the vehicle with supports while also using a transmission jack for transmission support. The procedure starts by removing the transmission support nuts at the mount. After lifting the transmission off the support you need to remove its crossmember bolts and crossmember. Start by loosening the exhaust muffler clamp then remove any necessary muffler insulators to disconnect the pipe from the muffler with the help of a jack stand for muffler support. Start by taking off the connector position assurance (CPA) retainer attached to the left front heated Oxygen Sensor (HO2S) then unplug the engine wiring harness electrical connector which provides power to this left front ho2s unit. Begin by taking off the cpa retainer which leads to disconnection of the engine wiring harness electrical connector from the left rear ho2s electrical connector . Use a jack to lower the transmission slightly while removing the left Catalytic Converter to exhaust manifold nuts and then loosen the exhaust manifold pipe to exhaust manifold nuts. Installation of a new left Catalytic Converter requires the removal of ho2s sensors (1 and 4). Before installing, apply gm p/n 12377953 anti-seize compound or its equivalent to the old sensor threads before installing ho2s (1 and 4) and tightening to 42 n.m (31 lb ft). Use a transmitter lift to slightly raise the vehicle then secure the left Catalytic Converter to exhaust manifold nuts following a torque specification of 50 n.m (37 lb ft). Secure the exhaust manifold pipe to exhaust manifold nuts with a torque of 50 n.m (37 lb ft). Next, connect the engine wiring harness electrical connector to the left rear ho2s electrical connector. Finish by installing the cpa retainer to the left rear ho2s. Install the cpa retainer onto the left front ho2s then use the engine wiring harness electrical connector to connect to this ho2s device. Screw the exhaust muffler clamp with a torque of 47 n.m (35 lb ft) then replace any exhaust muffler insulators which were removed. Install the transmission support crossmember while removing the jack stand from beneath the muffler and use a torque wrench to tighten the crossmember bolts to 95 n.m (70 lb ft). Put the transmission onto the support then install the transmission mount to transmission support nuts which require a torque of 95 n.m (70 lb ft). Remove the support from the transmission after that lower the vehicle.

To replace the Catalytic Converter in vehicles with 4.8l, 5.3l, 6.0l or 6.2l engines operators must first support their vehicle in the air then remove all bolts from the oil pan skid plate including the plate if the vehicle contains one before moving to the transmission crossmember. Next disconnect the right front heated Oxygen Sensor (HO2S) electrical connector from the engine wiring harness before removing the right front connector position assurance (CPA) retainer. First disconnect the right rear ho2s electrical connector by removing its clip and then repeat this step for the left rear ho2s. Vehicles with 4l60-e/4l70-e automatic transmission need left front cpa retainer removal and left front ho2s electrical connector disconnection. The Catalytic Converter to Muffler nuts need removal for 1500 series vehicles. Owners of 2500/3500 vehicles should remove Muffler to Catalytic Converter nuts. First remove nuts holding the Catalytic Converter assembly to the Exhaust Manifold and Muffler before severing the assembly from these components. During an assembly replacement ensure you discard the exhaust seals and remove oxygen sensors from the assembly. Before sensor installation smooth the ho2s threads with gm p/n 12377953 anti-seize compound followed by attaching the ho2s to the Catalytic Converter assembly and securing it to 42 n.m (31 lb ft). Attach the Catalytic Converter assembly to the combination of Muffler and exhaust manifolds by torquing both manifold nuts to 50 n.m (37 lb ft) and installing new exhaust seals if needed. For all vehicles except 2500/3500 series reattach the ho2s and tighten the Catalytic Converter to Muffler nuts to 45 n.m (33 lb ft). During 1500 series installment torque the Muffler nuts with same force as the Catalytic Converter. Tell the electrical ho2s connectors to connect and reinstall the cpa retainers. Reinstallation of the transmission crossmember gets followed by positioning the oil pan skid plate before tightening all bolts to 28 n.m (21 lb ft) and lowering the vehicle.