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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1732 (ENGINE EXHAUST SYSTEM)REPAIR INSTRUCTIONSEXHAUST MANIFOLD REPLACEMENT - LEFT (4.3L ENGINE)INSTALLATION PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Installation Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation Procedure
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
  1. Install the exhaust manifold heat shield and bolts, if required.

    Tighten 

    Tighten the bolts to 9 N.m (80 lb in).

    Fig 1: Installing Exhaust Manifold Heat Shield & Bolts - Left (4.3L)
    G02133442Courtesy of GENERAL MOTORS CORP.

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

  2. Install NEW exhaust manifold gaskets to the exhaust manifold.
  3. Ensure that the exhaust manifold bolts/stud, and plug wire shields are held in place by the tabs on the exhaust manifold gaskets.
    Fig 2: Installing Exhaust Manifold Gaskets - Left (4.3L)
    G02133443Courtesy of GENERAL MOTORS CORP.
  4. Install the exhaust manifold and plug wire shields.
  5. If reusing the old fasteners, apply threadlock GM P/N 12345493 (Canadian P/N 10953488), or equivalent to the threads of the exhaust manifold bolts/stud.
  6. Tighten the exhaust manifold bolts/stud.

    Tighten 

    Tighten the bolts/stud to 30 N.m (22 lb ft).

    Fig 3: Installing Exhaust Manifold & Plug Wire Shields - Left (4.3L)
    G02133444Courtesy of GENERAL MOTORS CORP.
  7. Connect the ECT sensor electrical connector (5).
    Fig 4: Connecting ECT Sensor Electrical Connector (4.3L)
    G02133445Courtesy of GENERAL MOTORS CORP.
  8. Install the spark plugs.

    Tighten 

    Tighten the plugs to 15 N.m (11 lb ft).

    Fig 5: Installing Spark Plugs - Left (4.3L)
    G02133446Courtesy of GENERAL MOTORS CORP.
  9. Position the wire harness to the engine.
  10. Install the spark plug wire retainer bolts.

    Tighten 

    Tighten the bolts to 12 N.m (106 lb in).

  11. Connect the spark plug wires to the spark plugs.
  12. Raise the vehicle.
    Fig 6: Installing Spark Plug Wires & Retainer Bolts - Left (4.3L)
    G02133447Courtesy of GENERAL MOTORS CORP.
  13. Install the exhaust manifold pipe nuts.

    Tighten 

    Tighten the nuts to 50 N.m (37 lb ft).

  14. Lower the vehicle.
    Fig 7: Installing Exhaust Manifold Pipe Nuts - Left (4.3L)
    G02133448Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.