I am searching the archives now, but have yet to find an answer to this one, and i am hoping that i can get some help.

My 06 MCS (stock aside from ALTA CAI) has just turned about 1850 miles, and has developed this evil buzzing from the rear hatch area when passing through 3900-4200 RPMs. It is a thin rattle, like sheet metal or something. Sounds almost like an electrical short sounds...

Sounds like it is from the inside, but not 100% sure. I took everything out of the hatch, including the plastic panels to the sides, and it is now louder then ever (of course). I am going to go try the electrical tape around the hatch latch, but this sounds much more tinny - not as solid as i assume that would sound. I am also going to poke my head underneath & see if the exhaust battery shield is touching anything...

Any ideas?

thanks!

-jac

 

Our 06 MCS is at about 2500 and we haven't had this so far. The first things I'd do are:

--check the storage pockets, something in there might be rattling
--if you have the H/K audio set up, open the right cubby in the boot where the amp is and check that it is mounted tightly
--check that the license plate screws are not loose
--check where the rear seatbelts buckles are resting along the strap--at some locations they may vibrate against stuff and that might be inflenced by RPM

GOOD LUCK!

 

if you lay on your back and look up behind the bumper, you will see a nicely made heat wrap that surrounds the upper exhaust area to protect the interior from exh. heat. sometimes this touches the bumper/floor.what have you where it shouldnt and can set up a vibration and noise like you describe. it is soft and easily formed with your hands, no tools needed. you can just slide your fingertips in between it and the bumper (make sure car/exhaust is cold!!) and gently push it around to clear anything it might be touching. good luck, hope this helps.

 

Yep, sounds like a heat shield buzz. Mine does the same at 3000-3500 RPM.

 

Another possible culprit is the seatbelt adjusters for the front seats or rear (where the seatbelt mounts to the pillar there is a slide adjustment). I'm pretty certain that is the source of the occasional buzz i hear but I haven't bothered to check it out yet

 

thanks for all the help guys. it is 100% the heat shield under the car. It's coming from right above the drivers side "ball" I was able to make it a little better, but I don't think i can fix it without dropping the exhaust down a little.

Just going to have to keep the Pearl Jam cranked on the HK until i can get it in to Ottos next week.

thanks!

 

OK, apparently what I thought was a heat shield buzz, isn't. Played with the shields yesterday, found that the muffler shield was tucked under the bumper on one side, and hanging below on the other, so I made everything the same; still making noise. Tried the header shield, same thing. Noticed that the noise only comes on when I let off the gas and coast down thru the noted RPM range. Does not make the noise when I attempt to duplicate while stationary. Also getting some noise (halfway between a whirr and a grind) with clutch released, but in neutral; goes away when the clutch pedal is depressed.
Sound like a throw out bearing? Or something else transmission related?

 

mine turned out to be a crack in a weld on the exhaust. Dealership threw a new one on there - all fixed!

thanks again for the input!

-jac