GM 19420098
Catalytic Converter

In order to change the Catalytic Converter on engines 4.8l and 5.3l, first lift and fix the vehicle, and hook the transmission with an appropriate transmission jack. Remove the transmission mount to transmission support nuts, lift the transmission off the support, and the remove the transmission support crossmember bots and nuts prior to removing the crossmember itself. Next, unclip the engine harness and oxygen sensor pigtail, slacken the cpa retainers, and remove the oxygen sensor electrical connectors. Unclip these connectors from the hose clip and transmission crossmember and remove the left and right exhaust manifold pipe nuts, the exhaust muffler nuts, and the Catalytic Converter lastly. If replacing the Catalytic Converter, apply anti-seize compound gm p/n 12377953, or equivalent, to the threads of the old oxygen sensors and reinstall them, tightening to 42 nm (31 ft. Lbs.). Replace the old Catalytic Converter with a new one and fit new exhaust manifold pipe seals, then tighten the right and left exhaust manifold nuts sixareally then tighten them to 50 nm (39 ft. Lbs.). Introduce the exhaust muffler nuts then tighten them up to 40 nm (30 ft. Lbs.). Reconnect the electrical connectors of oem o2 sensor & cpa retainers, attach the connectors to the hose clip & transmission crossmember & install the clip of engine harness & o2 sensor pigtail. Replace the transmission support cross member and tighten the bolts to 95 nm (70 ft. Lbs.), lower the transmission to the support and install the transmission mount to transmission support nuts tightening both to 40 nm (30 ft. Lbs.). Lastly, take off the transmission jack and lower the vehicle.

The procedure to change the left Exhaust Pipe of a 6.6l (LLY) engine starts with right wheelhouse panel removal followed by removing Exhaust Heat Shield nuts and heat shield from dash panel. Move on to the second step where you should detach left Exhaust Pipe heat shield bolts along with the heat shield itself. Remove the Exhaust Pipe bolts adhering to proper sequence and then take out the Exhaust Pipe with its gaskets before throwing away the old gaskets. Place the Exhaust Pipe together with its new gasket against the Turbocharger while maintaining the gasket tab toward the inside before installing the bolts loosely. Install the Exhaust Pipe with its new gasket against the Exhaust Manifold while aligning the tab toward the outside and then install the bolts loosely. Secure the Exhaust Pipe bolts in their specified order to 53 nm (39 ft. Lbs.) and fasten the Exhaust Pipe heat shield bolts to 8 nm (71 inch lbs.). After positioning the left side Exhaust Heat Shield at the dash panel you must fasten it with heat shield nuts before tightening each one to 9 nm (80 inch lbs.). Put back the right wheelhouse panel as the final step.

The replacement process for exhaust manifold pipes installed in 6.0l 6.6l and 8.1l engines starts by elevating and stabilizing the vehicle after which transmission support requires a suitable transmission jack. Begin by removing the transmission mount to transmission support nuts before lifting the transmission off its mount and continuing to dispose of the transmission support crossmember bolts along with the crossmember itself. The replacement process for 6.0l or 8.1l engines includes exhaust Muffler removal followed by engine harness clip and Oxygen Sensor pigtail disconnection and then separating the cpa retainer and Oxygen Sensor electrical connector before extracting the Oxygen Sensor. After removing exhaust manifold pipe nuts, users need to shift the transmission slightly downward before completing the exhaust Muffler nut removal step for 6.6l engines and applying the Exhaust Pipe clamp toward the Exhaust Pipe adapter. The exhaust manifold pipe requires removal together with disposal of the utilized seal. New exhaust manifold pipe installation requires water-based lubrication on the hanger bracket for 6.6l engine models. Position the hanger into the bracket while applying a new seal to engines with rpo y91 before installing the exhaust manifold pipe. The exhaust manifold pipe installation requires repeating the lubrication procedure for 6.0l or 8.1l engines with careful alignment of the manifold pipe to the Exhaust Pipe adapter. Secure the Exhaust Pipe clamp at 40 nm torque while the Muffler nuts require 40 nm torque adjustment. When performing work on 6.0l or 8.1l engines you should put on the exhaust manifold pipe nuts then torque them to 50 nm (39 ft. Lbs.). Mount the transmission and apply anti-seize compound gm p/n 12377953 to existing Oxygen Sensor threads. Install the sensor by tightening it to 42 nm (31 ft. Lbs.). The Oxygen Sensor electrical connector and cpa retainer along with the engine harness clip should be reattached if the Exhaust Pipe was not exchanged. For engines with either 6.0l or 8.1l displacement install the exhaust Muffler followed by the transmission support crossmember and its bolts secured at 95 nm (70 ft lbs.). Place the transmission on the support before installing transmission mount support nuts at 40 nm (30 ft. Lbs.) torque and take off the support from the transmission while lowering the vehicle.

Vehicle elevation and correct support must be accomplished as the first step for replacing exhaust manifold pipes on 6.0l and 8.1l engines. A suitable transmission jack will support the transmission for you to remove the transmission mount to transmission support nuts then lift the transmission off its support. Start by removing the transmission support crossmember bolts before taking out the crossmember then you should detach the exhaust Muffler. The removal process starts with disconnecting the clip from both engine harness and Oxygen Sensor pigtail before separating the connector position assurance (CPA) retainer and Oxygen Sensor electrical connector to remove the Oxygen Sensor. Lower the transmission with the jack and remove the exhaust manifold pipe by discarding its old seal while disconnecting the exhaust manifold pipe nuts. A fresh exhaust manifold pipe seal should be positioned onto the exhaust manifold pipe before securing the pipe through installation. After lifting the transmission with the jack, ensure the exhaust manifold pipe nuts reach 50 nm torque (39 ft. Lbs.). Apply gm p/n 12377953 anti-seize compound or equivalent to the threads of a reused Oxygen Sensor before tightening it to 42 nm (31 ft. Lbs.). The Oxygen Sensor electrical connector and cpa retainer must be connected before installing the clip that wraps around the engine harness and Oxygen Sensor pigtail. Begin by installing the transmission support crossmember with its bolts to a torque of 95 nm (70 ft. Lbs.). After installing the exhaust Muffler you can proceed with putting back the transmission support crossmember and tightening its bolts to 95 nm (70 ft. Lbs.). Screw the transmission mount onto the transmission support nuts until they reach 40 nm (30 ft. Lbs.). Follow the last step by taking away the transmission jack before dropping the vehicle to the floor.

To replace 4.3l, 4.8l, and 5.3l engines' Catalytic Converter, first raise and supporting the vehicle. If present, unclip the Oxygen Sensor connection from the floor reinforcement and disconnect the Oxygen Sensor electric connector and unclip the clips from the frame. Pull off the connector position assurance (CPA) retainers and Oxygen Sensor electrics. Unclip the Oxygen Sensor electrical connectors at the hose clip and transmission crossmember, and remove the cpa retainers and the Oxygen Sensor electrical connectors (1, 2). Remove the left and right exhaust manifold pipe nuts, nuts to the exhaust muffler and then remove the Catalytic Converter. If needed, take out the oxygen sensors. For installation, as needed, install the oxygen sensors and apply the anti-seize compound gm p/n 12377953 or equivalent to the threads of the old oxygen sensors before installation and tight to 42 nm (31ft. Lbs.). Replace new exhaust manifold pipe seals to the exhaust manifolds and then replace the right and left exhaust manifold pipe nuts neatly to 50 nm (39 ft. Lbs.). Mount the exhaust muffler nuts and tighten them to 40 nm (30 ft. Lbs.). Connect the Oxygen Sensor electrical connectors (1, 2) and retainers to the cpa retainers and clip the Oxygen Sensor electrical connectors to the hose clip and transmission cross member. Connect the Oxygen Sensor electrical connectors and cpa retainers, as well as install the clip around the engine harness and the Oxygen Sensor pigtail and connect the Oxygen Sensor electrical connector. If available, clip the Oxygen Sensor connection to the floor reinforcement, despite lowering the vehicle.

Apply anti-seize compound GM P/N 12377953 to the threads of the HO2S if reusing old sensors, then install the HO2S to the catalytic converter assembly and tighten to 42 N.m (31 lb ft).

Remove the left and right exhaust manifold pipe nuts, followed by the exhaust muffler nuts, and then remove the catalytic converter.

Remove the left and right exhaust manifold pipe nuts, followed by the exhaust muffler nuts, and then remove the catalytic converter.

Repeat the process of removing the respective CPA retainers and clips.