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1999 Corvette: Service Bulletin: Left Fuel Tank to Underbody Contact/Rattle Noise

Subject: Left Fuel Tank to Underbody Contact/Rattle Noise (Install Foam Insulator Pad)
Source: Chevrolet Service Bulletin
Number: 99-06-04-052
Models: 1999 Chevrolet Corvette


Some customers may comment on a rattle type noise that appears to be coming from behind the driver’s seat area. This noise typically can be generated when the vehicle is operated in a manner that results in a body twisting motion, such as turning into a steep driveway.


The forward vertical face of the left fuel tank may contact the vehicle underbody in the kick-up area rearward of the driver’s seat during certain driving maneuvers.


Install fuel tank foam insulator pad, P/N 12493728, between the vertical forward face of the left fuel tank and the vehicle’s underbody following the service procedure below.

    1. Raise the vehicle and suitably support.
    2. Remove fuel tank shield from left fuel tank.
    3. Support left fuel tank strap and tank assembly.
    4. Remove fuel tank strap bolts.
    5. Lower fuel tank strap and tank assembly to gain access between the front surface of the fuel tank assembly and the underbody, approximately 25 mm (1 in).
    6. Remove the backing paper from the foam insulator pad, P/N 12493728.
    7. With the wide side of the pad facing downward and the sticky side facing towards the tank, carefully slide the pad between the tank and the underbody. With the pad positioned centrally cross-car on the vertical face of the tank and approximately 50 mm (2 in) from the bottom surface of the tank, press on the pad securing it to the tank.
    8. Raise the fuel tank strap and the tank assembly up into position and hand start the fuel tank strap bolts.
    9. Tighten the fuel tank strap bolts in the following order: Tighten

      Tighten the fuel tank strap bolts to 25 N·m (18 lb ft).
  • Front inboard bolt
  • Middle inboard bolt
  • Two outboard bolts


  1. Install the fuel tank shield and hand start the attaching bolt and nut.
  2. Tighten the fuel tank shield attaching bolt and nut. Tighten

    Tighten the attaching bolt and nut to 25 N·m (18 lb ft).

  3. Remove the supports and lower the vehicle

Parts Information

Part Number



Tank Insulator Pad


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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