Muffler Buzz During Vehicle Operation or Exhaust Popping/Snapping Noise When Vehicle is Hot, at Idle, or Immediately After Vehicle is Shut Off (Replace Straps on Muffler Heat Shield)

This bulletin is being revised to address two common exhaust system concerns. Please discard Corporate Bulletin Number 07-06-05-001A (Section 06 -- Engine/Propulsion System).

Some customers may comment on a popping/snapping noise from underneath the vehicle at idle or immediately after the vehicle is shut off. Some popping/snapping noise from the exhaust system during cool down is a normal condition. The noise may be intermittent depending on the outside temperature and or temperature of the exhaust system at the time of testing.

Some customers may also comment on a buzz noise coming from the muffler during vehicle operation.

Exhaust Popping/Snapping:

As the exhaust system cools, the muffler shell and muffler internals contract at different rates. Some popping/snapping noise from the exhaust system during cool down is a normal condition.

Muffler Buzz:

If the muffler heat shield straps are loose, the heat shield may be free to buzz.

DO NOT REPLACE THE EXHAUST SYSTEM COMPONENTS.

Exhaust Popping/Snapping Noise:

This condition is normal to the muffler design and does not indicate poor quality or part failure.

Muffler Buzz:

Confirm the origin of the buzz by shimming (use metal shims) the straps tight and rerunning the vehicle. If the buzz concern is gone, then it is caused by the loose shield. Using the following procedure, install new straps to secure the heat shield to the muffler.

1. Install three straps, P/N 10391259, so that the strap screw head will be located on top of the muffler.

Tighten
tighten the strap screw to 4 N·m (35 lb in).

2. Cut off the excess strap material and bend the strap over the strap screw head.

For vehicles repaired for a muffler buzz, use the following labor operation: