GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 2WD 🢒 General Information 🢒 General Information 🢒 Exhaust Manifold Replacement - Left Side

Removal Procedure

    Object Number: 444792 Size: SH
  1. Disconnect the breather tube at the air cleaner outlet duct.

    2. Object Number: 312278 Size: SH
  2. Remove the air cleaner outlet duct retaining wingnut.

    3. Object Number: 10940 Size: SH
  3. Disconnect the IAT sensor harness connector.

    4. Object Number: 424556 Size: SH
  4. Remove the air cleaner outlet duct from the throttle body.
  5. Remove the intermediate steering shaft. Refer to Lower Intermediate Steering Shaft Replacement in Steering Wheel and Column.

    6. Object Number: 246797 Size: SH
  6. Disconnect the engine coolant temperature (ECT) sensor electrical connector.

    7. Object Number: 341247 Size: SH
  7. Remove the radiator inlet hose support bracket and nut.
  8. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  9. Disconnect the exhaust pipe from the exhaust manifold. Refer to Exhaust Manifold Pipe Replacement .

  10. Lower vehicle.
  11. Remove the front tire to gain access to the rear exhaust manifold bolts. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.

    12. Object Number: 303008 Size: SH
  12. Remove the fender wheelhouse extension.
  13. Working through the wheel house opening disconnect the spark plug wires from the spark plugs.
    14. 13.1. Rotate the spark plug wire boot one half turn.
    13.2. Pull outward on the spark plug wire boot to release from the spark plug.

    Object Number: 341362 Size: SH
  14. Remove the exhaust manifold bolts and the stud.
  15. Lower the vehicle.
  16. From under the hood remove the exhaust manifold and the spark plug wire shields from the engine.

    17. Object Number: 328540 Size: SH
  17. Remove and discard the exhaust manifold gaskets.
  18. Clean all gasket surfaces. Refer to Exhaust Manifold Cleaning and Inspection in Engine Mechanical - 4.3L Unit Repair.

Installation Procedure

    Object Number: 476818 Size: SH

    Important: To assist in installing the exhaust manifold to the engine, the tabs on a NEW exhaust manifold gasket will hold the gasket and bolts in place.

  1. Sub-assemble the bolts, spark plug wire shields, and NEW gaskets to the exhaust manifold.

    2. The stud installs in the front hole.

  2. Ensure that the exhaust manifold bolts are held in place by the tabs on the exhaust manifold gaskets.
  3. From under the hood position the exhaust manifold by the engine.
  4. Raise the vehicle to the proper height.

    5. Object Number: 188045 Size: SH
  5. Working the wheelhouse opening, install the exhaust manifold.
  6. Install the spark plug wire shields.
  7. If reusing the fasteners, apply threadlock GM P/N 12345493 (Canadian P/N 10953488) or equivalent to the threads of the exhaust manifold bolts and stud.

    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.

  8. Install the exhaust manifold bolts and stud.

    9. Tighten

    1. Tighten the exhaust manifold bolts and stud on the first pass to 15 N·m (11 lb ft).
    2. Tighten the exhaust manifold bolts and stud on the final pass to 30 N·m (22 lb ft).
  9. Install the spark plug wires to the spark plug wire retainers.
  10. Install the spark plug wires onto the spark plugs.

    11. Object Number: 303008 Size: SH
  11. Install the fender wheelhouse extension.
  12. Install the front tire to. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
  13. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  14. Connect the exhaust pipe to the exhaust manifold. Refer to Exhaust Manifold Pipe Replacement .
  15. Lower the vehicle.

    16. Object Number: 246797 Size: SH
  16. Connect the ECT sensor electrical connector.

    17. Object Number: 341247 Size: SH
  17. Install the radiator inlet hose support bracket and nut.

    18. Tighten
    Tighten the radiator inlet hose support bracket nut to 36 N·m (27 lb ft).

  18. Install the intermediate steering shaft. Refer to Lower Intermediate Steering Shaft Replacement in Steering Wheel and Column.

    19. Notice: 

       • Handle the MAF sensor carefully.
       • Do not drop the MAF sensor in order to prevent damage to the MAF sensor.
       • Do not damage the screen located on the air inlet end of the MAF.
       • Do not touch the sensing elements.
       • Do not allow solvents and lubricants to come in contact with the sensing elements.
       • Use a small amount of a soap based solution in order to aid in the installation.


    Object Number: 424556 Size: SH
  19. Install air cleaner outlet duct to throttle body.
  20. Install air cleaner outlet duct to MAF sensor.

    21. Object Number: 10940 Size: SH
  21. Connect the IAT sensor harness connector.

    22. Object Number: 312278 Size: SH
  22. Install the air cleaner outlet duct retaining wingnut.

    23. Object Number: 444792 Size: SH
  23. Connect the breather tube to the air cleaner outlet duct.