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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 78 (ENGINE EXHAUST SYSTEM)REPAIR INSTRUCTIONSEXHAUST MANIFOLD REPLACEMENT - LEFT SIDEINSTALLATION PROCEDURE
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Installation Procedure

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Installation Procedure
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
  • Tighten the exhaust manifold bolts as specified in the service procedure. Improperly installed and/or leaking exhaust manifold gaskets may affect vehicle emissions and/or On-Board Diagnostic (OBD) II system performance.
  • The cylinder head exhaust manifold bolt hole threads must be clean and free of debris or threadlocking material.
  • Do not apply sealant to the first 3 threads of the bolt.
    Fig 1: View Of Exhaust Manifold, Manifold Bolts & Gasket
    GM1708615Courtesy of GENERAL MOTORS CORP.
  1. Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493 (Canadian P/N 10953488), or equivalent to the threads of the exhaust manifold bolts.
  2. Position the NEW exhaust manifold gasket and exhaust manifold to the cylinder head.
    3. NOTE: Refer to Fastener Notice .
  3. Install the exhaust manifold bolts.

    Tighten: 

    1. Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.
    2. Tighten the bolts a final pass to 20 N.m (15 lb ft). Tighten the exhaust manifold bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.

  4. Using a flat punch, bend the gasket tab at the rear of the gasket around the cylinder head edge.
  5. Raise the vehicle.
    6. Fig 2: View Of Exhaust Manifold, Gasket & Catalytic Converter
    GM1708614Courtesy of GENERAL MOTORS CORP.
  6. Ensure that the exhaust seal is seated in the catalytic converter.
  7. Install the catalytic converter to exhaust manifold nuts. (1500 series shown, 2500 series similar).

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

  8. Lower the vehicle.
  9. Install the spark plugs. Refer to Spark Plug Replacement .
  10. Install the ignition coils. Refer to Ignition Coil Replacement .
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.