The muffler heat shield may become loose on the muffler causing a rattle or popping noise. Our technicians tell us there is a kit available from GM to correct this problem.
Average mileage: 141,792 (115,000–206,757)
Exhaust & Emissions affected: V8
14 people reported this problem
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Loud rattling noise coming from under the rear of the car. Have not had it diagnosed yet, but souinds like this may be the cause. The noise is not constant. Usually at slow speeds. Independent of whether the car is warm or not.
Loud Vibration/Humming Noise coming from under truck when accelerating from very slow speeds - up driveways, etc or in parking lots. Sounds like vibrating plate or heat shield "tinny" vibration short lived for a few seconds and disappears. Occurs at least once daily.
Heat shield cracked. Had a muffler shop to weld it. But, after about 10k miles it has cracked again.
upon accelaration, I hear the vibration of the muffler.