GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1996 🢒 GMC G Van 🢒 Engine 🢒 Engine Exhaust 🢒 Catalytic Converter Replacement

Removal Procedure
  1. Raise the vehicle.
  2. Support the vehicle with safety stands.

    3. Object Number: 21585 Size: SH
  3. Remove the oxygen sensor electrical connection.

    4. Object Number: 78428 Size: SH
  4. Remove the nuts and the seals from the exhaust manifold pipes. (Gasoline Engine)

    5. Object Number: 78429 Size: SH
  5. Remove the nuts and the seals from the exhaust manifold pipes. (Diesel Engine)

    6. Object Number: 72788 Size: SH
  6. Remove the clamp from the front of the muffler.

    7. Object Number: 72774 Size: SH
  7. Remove the catalytic converter assembly.

Installation Procedure
  1. Apply the GM P/N 9985020 sealer, or equivalent, to the slip-joint connections.

    2. Object Number: 72774 Size: SH
  2. Install the new catalytic converter assembly into the front muffler pipe.

    3. Object Number: 72788 Size: SH
  3. Install the new clamp at the front of the muffler.

    4. Object Number: 78428 Size: SH
  4. Install the new seals and nuts to the exhaust manifold pipes. (Gasoline Engines)

    5. Object Number: 78429 Size: SH
  5. Install the new seals and nuts to the exhaust manifold pipes. (Diesel Engines)

    6. Tighten

       • 

    Tighten the clamps to support 48 N·m (35 lb ft).

       • 

    Tighten the exhaust manifold nuts to 65 N·m (48 lb ft).

    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.


    Object Number: 21585 Size: SH
  6. Install the oxygen sensor electrical connection.
  7. Check the system for clearance and alignment.
  8. Lower the vehicle.