GM Service Manual Online
For 1990-2009 cars only

Front Pipe Replacement W/ TWC

Removal Procedure

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

  2. Object Number: 185746  Size: SH
  3. Remove two bolts and the front pipe/TWC assembly (2) from the exhaust manifold (1).

  4. Object Number: 185751  Size: MH
  5. Remove the electrical connector at the heated oxygen sensor (H02S2) (3).

  6. Object Number: 166026  Size: SH
  7. Remove two nuts and the front pipe/TWC assembly from the resonator/muffler/tail pipe assembly.
  8. Remove the hanger supporting the TWC.
  9. Remove the front pipe/TWC assembly from the vehicle.
  10. Clean the gasket and the seal mating surfaces.

Installation Procedure

Important: When installing a new exhaust system component, always use new gaskets and seals.

  1. Install the front pipe/TWC assembly to the vehicle.
  2. Support the TWC with a hanger.
  3. Attach the front pipe/TWC assembly with a new gasket to the resonator/muffler/tail pipe assembly.
  4. Secure the resonator/muffler/tail pipe assembly with two nuts. Do not fully tighten the nuts.

  5. Object Number: 185751  Size: MH
  6. Attach the electrical connector to the heated oxygen sensor (H02S2) (3).
  7. Connect the front pipe/TWC assembly, with a new seal, to the exhaust manifold and secure with two bolts. Do not fully tighten the bolts.
  8. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  9. Align all system components before tightening the fasteners, in order to prevent noise or vibrations.
  10. Tighten

        • Tighten the front pipe/TWC assembly-to-exhaust manifold bolts to 50 N·m (37 lb ft).
        • Tighten the front pipe/TWC assembly-to-resonator/muffler/tail pipe assembly nuts to 35 N·m (26 lb ft).
  11. Lower the vehicle.