Insanely loud muffler/exhaust vibration

[fourmotioneer]

On my new 318is, when I hit 65mph, my muffler begins to rattle a lot. The exhaust tip shows wear where it contacts the valence cut-out. When I push up on the muffler, I can hear a metallic contact with the metal shield above.

I've tried replacing the mount right before the muffler. I suspect that replacing the two muffler mounts will just cause the exhaust tip to become closer to the valence. I've also heated and bent the exhaust tip to center it in the cut-out.

Any ideas? I was planning on driving from Indiana to Seattle starting tomorrow but this is almost unbearable.

[bmwman91]

The cat or resonator could also be hitting the heat shield. That 's pretty common if an exhaust shop does a shitty job installing a replacement cat.

[fourmotioneer]

The cat or resonator could also be hitting the heat shield. That 's pretty common if an exhaust shop does a shitty job installing a replacement cat.

Thanks for the input. I can see that. At this point, I'd like to drop it at an exhaust shop to get it over with. What would you expect that they would do to address that? I think the cat/resonator are original. In general, should I hope to be successful in going to an exhaust shop and asking them to stop a vibration/rattle like this? I usually don't take my car places for work, but I'm a bit low on time.

[mr ilia]

Should be none issue for any typical exhaust shop to determine where the noise/vibration is coming from.

[fourmotioneer]

Exhaust shop says that the muffler has internal damage and something inside of it is shaking.

I may remove it for the trip. That, or swap one from the other car. We'll see how it sounds with the muffler off...

[bmwman91]

Yeah way back in the day I had a stock muffler get VERY loud. An internal baffle came loose. And then I went with a Supersprint setup that has no internal baffles and never looked back.

[roguetoaster]

I may remove it for the trip. That, or swap one from the other car. We'll see how it sounds with the muffler off...

Loud, it sounds loud.

[fourmotioneer]

Aaaand I took the 84 GTI instead (2,500 miles so far)

The rear wheel bearing is likely the culprit, as I finally got the car off the ground and was able to check that. Since it's speed dependent, this makes sense.

That is, unless the issue is the muffler (which I inspected and has loose baffles) and the wheels are out of balance such that they excite the muffler in that speed range.

Thanks for the help - with the impending trip, I can take my time on this one.