Noisy exhaust on 96

[sgbuick]

I am having a similar problem on my 96 Caprice that I had on a prev. 96 Roadmaster: Instead of being completely quiet, the exhaust has a deep sound reminiscient of Dynomax Super Turbo mufflers, without having any obvious leaks anywhere. When standing outside, the sound mostly seems to come out the back by the exhaust pipe, and only when you rev the engine. It is the original factory muffler/exhaust, 70K miles. You hear it mainly when about halfway into the gas pedal. Did they have some kind of internal baffle problem or something? It is not really loud, but still very noticeable in such a quiet car. Anyone else have the same problem?

[sgbuick]

Anyone?

[Blue Bowtie]

The original exhaust consisted of converters, baffled mufflers, and screen/ceramic wool resonators at the rear. If the muffler baffles have eroded away, you can get the drone you describe.

[sgbuick]

Yeah, I thought it might be the internal baffles, since there doesn't seem to be any external leaking. I guess the resonator wouldn't be the issue, it doesn't control the deeper bass sound from the exhaust, right? Thus it is probably not a resonator issue. It is really not that loud, just a very noticable hum under the car when accelerating, almost sounds like one of those Dynomax Super Turbo mufflers even though it is the original factory muffler system.

[silicon212]

Originally Posted by sgbuick

Yeah, I thought it might be the internal baffles, since there doesn't seem to be any external leaking. I guess the resonator wouldn't be the issue, it doesn't control the deeper bass sound from the exhaust, right? Thus it is probably not a resonator issue. It is really not that loud, just a very noticable hum under the car when accelerating, almost sounds like one of those Dynomax Super Turbo mufflers even though it is the original factory muffler system.

The resonators tend to give the system a noticeable 'growl' under acceleration (I have a mostly LT1 setup under my '88), but shouldn't cause the drone. I would also suspect muffler baffling as the culprit here. However, loose or worn exhaust system hanging equipment can also cause a drone.

GM sells (sold) a part, designed for the Roadmaster (but can be used under any '77-'96 B-body), that addresses this exhaust drone. It is GM P/N 10225142 and has a nice side effect of strengthening the frame, helping out your cars' handling capability.