Front Exhaust Pipe And Catalytic Converter: Installation

NOTE: When installing a replacement front exhaust pipe and catalytic converter assembly, three bolts and three nuts will be required to make the installation to the intermediate pipe. The replacement front exhaust pipe has a 6-hole flange at the outlet of the converter (vs. three studs on the production assembly).

Install a new gasket on exhaust manifold studs.
Install two rubber isolators supporting the front exhaust pipe to hanger rod on pipe.
Install front exhaust pipe-to-manifold nuts.
Torque:

Exhaust Pipe-to-Manifold: 31 N.m (23 ft-lbs)

Fig 1: Installing Front Exhaust Pipe To Manifold
Courtesy of GENERAL MOTORS CORP.

NOTE: When installing a replacement front exhaust pipe, procure an exhaust pipe hanger clamp for installation on the pipe.
Slide front exhaust pipe clamp over engine block bracket and tighten clamp.
Torque:

Exhaust Pipe Clamp-to-Support

Bracket: 60 N.m (44 ft-lbs)
Install catalytic converter outlet gasket and fasten outlet to intermediate pipe with nuts.
Torque:

Catalytic Convertor-to-Isolator: 25 N.m (19 ft-lbs)

Fig 2: OS2 Sensor Harness
Courtesy of GENERAL MOTORS CORP.

NOTE: Always use a nickle-based anti-seize compound Saturn P/N 21485279 (or equivalent) on the threads of the Heated Oxygen Sensor (HO2S-2). If the HO2S-2 is replaced, do not apply anti-seize to the new sensor. New sensors have anti-seize pre-applied. Never use silicone products; silicone products will damage the sensor.
Install Heated Oxygen Sensor (HO2S-2) using Oxygen Sensor Wrench Remover/Installer SA9603E.
Torque:

Sensor - Oxygen-to-Exhaust Manifold: 45 N.m (33 ft-lbs)
Attach the HO2S-2 harness to the clips on the converter heat shield.
Connect HO2S-2 harness to connectors and install connector position assurance clip.
Install tab on harness connector to the hole in engine cradle.
Lower vehicle to ground, start engine, and check for exhaust leaks.