I have a scorpion exhaust installed in my 05 MCS that I have had for a few months. I just recently installed a rear seat delete panel that I have made. I can hear an exhaust vibration at idle and only at idle that gets kind of annoying. I checked to make sure nothing is hitting under the car and all seems ok, I even checked the bolts and everything is tight. Any ideas? I even removed the battery protective cover to check to see if that was the problem, but no luck. I also checked the heat shields. Also I installed a rear seat delete panel not to long ago. well just today I am starting to get this tapping noise in the back of the car that almost sounds like a seat belt hitting the plastic. But i made sure that was not the problem. I even removed the panel to see if that was maybe causing the problem and the noise still accord. This happends when you hit a bump in the road or drive on a bumby road. Does anyone have any suggestions?

Garrett

 

It's not listed in your mod's list. But do you have any suspension work done? Or have you undone the swaybar links for any reason? That bolt when not fully tightened makes the noise you are describing.

And your exhaust may not be contacting the heat shield when the car is parked, but you might want to check if its "close" anywhere. Mine doesnt actually touch when parked, but when driving i know its making contact which makes the vibration feeling.

I will try thinking about this more and will let you know what i come up with. :smile:

 

suspension is stock. And the sway bar is also stock. I really cant do anything right now to try and solve this problem as the car will be at the dealer for a week or so. But I wanted to get a head start on ideas that I can look into to get rid of this problems. May have someone sit in the back and listen for the noise while I drive.

Garrett

 

I have the same noise.......Im narrowing it down to the hatch or trunk side panels which will get some dynamat soon. I know on prior year MC the catch on the trunk was no good but those should be updated on your year.

 

I have read some where that some people had to tighten the latch and the noise went away. I guess I am noticing more noises as I do not have the rear seat in the car anymore. it does not bother me to much as I have the music on most of the time. But do not want others who drive in the car think anything different! I will miss my car for the next week as it is getting some paint work fixed. So I really can not be productive on it when its not with me :(. Keep me informed if you have found the solution!

Thanks,

Garrett

 

I have had a few tapping noises with regard to the exhaust. One which I haven't fully fixed is where the resonator pipe touches the plate which holds it up. This happens on idle sometimes and under hard accelartion. I find it works well that while under the car, grab the exhaust and pull it from side to side. See where it can hit and move to. Then make appropriate adjustments.

 

I have tried that and saw nothing that can hit the car. The exhaust that I have does not come with a resinator so I do not have that issue by the plate. When you try to move the exhaust it is pretty tight to move it. Also when the car is cold and I start it up, it does not make the vibration noise, it only starts when the car warms up at idle and then begins and continues when only at idle and not at accelaration.

Garrett

 

I wonder if its an internal problem with the exhaust Magnaflow had problems with resonators for a while. I know you said yours doesn't have a resonator but it could be something else.

I have just learned quickly how even the slightest rub or touching of the car creates a vibration or annoying noise. Ahh the aftermarket installed by me

 

The vibration is deff. a noise that is vibration from the back of the car. I guess the exhaust is putting out more and causing it to vibrate what ever is in the back of the car and making the vibration noise. As for the knocking noise I get when going over small bumps or a rough road. It could be the hatch latch. It amlost sounds like the seat belt is hitting the plastic, but I have them so they do not bump into the side when I am driving.

Garrett

 

You dont say! jk

 

That (a problem with something internal to the new exhaust) would be my vote. To conclusively prove it, you would need to remove the aftermarket exhaust and replace it with the factory exhaust. It does happen. GM had a huge problem with the exhaust systems on the 2003 Yukon Denalis. (May have also had the problem on the base Yukons as well - same exhaust.) The exhaust would make a noise just like you have described.

If you have a problem with the muffler internals, I tend to doubt that dynamat will solve the problem.

 

Our 05 MCSa had a vibration related sound at idle that went away when accelerating but would reoccur on certain bumpy surfaces. Checked seat belts and rear tray but they were O.K. Finally lucked into touching that little box on the ceiling above rear seat and holding pressure on it and the rattle went away. Removed the box and found unused (unplugged) connector and velcroed it to the box cover and the rattle is GONE. I love simple fixes and hope this might help someone else.

Multum in parvo

 

I will have to give that a shot! Thanks for the heads up. :smile:

Garrett