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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 402 (ENGINE EXHAUST SYSTEM)REPAIR INSTRUCTIONSEXHAUST MANIFOLD PIPE REPLACEMENT - FRONT (L47)INSTALLATION PROCEDURE
1999 GMC Forward Control 5.7 R, Automatic

Installation Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Installation Procedure
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: When inspecting or replacing exhaust system components, make sure there is adequate clearance from all points on underbody to prevent overheating on the floor pan and possible damage to the passenger compartment insulation and trim materials.
  1. Place the retainer and a NEW front exhaust manifold pipe seal over the left exhaust manifold.
  2. Insert the front exhaust manifold pipe (2) around the left exhaust manifold.
    CAUTION: Refer to FASTENER NOTICE .
  3. Install the bolts (1, 3) securing the front exhaust manifold pipe (2) to the engine.

    Tighten 

    Fig 1: Installing Front Exhaust Manifold Pipe
    G01818222Courtesy of GENERAL MOTORS CORP.

    Tighten the front exhaust manifold pipe support bolts to 25 N.m (18 ft lbs).

  4. Install the nut securing the coil cassette ground wire to the cylinder head.

    Tighten 

    Tighten the coil cassette ground wire nut to 17 N.m (13 ft lbs).

  5. Install the two bolts securing the front exhaust manifold pipe to the left exhaust manifold.

    Tighten 

    Tighten the front exhaust manifold pipe bolts to 25 N.m (18 ft lbs).

    6. Fig 2: Installing Left Exhaust Manifold To Front Exhaust Manifold Pipe Bolts
    G01818223Courtesy of GENERAL MOTORS CORP.
  6. Hand start the EGR inlet pipe nut to the front exhaust manifold pipe to prevent crossthreading.

    Tighten 

    Tighten the EGR inlet pipe nut to 60 N.m (44 ft lbs).

  7. Install the transaxle assembly. Refer to TRANSAXLE (4T80-E) .
  8. Install the rear exhaust manifold pipe. Refer to Exhaust Manifold Pipe Replacement - Rear (L47) .
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.