I have had what I thought was the typical hatch rattle that plagues most crossfire drivers. After proper searching, I have applied every known fix. I'm talking about 4-5 sessions of adjusting bumpers, electrical tape wrapping, velcro padding. I have been fooled several times that the demon rattle was fixed. I would run the car around the block and everything would seem fine. Then it would pop back up the next day.

I don't know if I can fit, but I'm about to have my wife put me in the trunk and drive around with me back there. From the driver seat it seems to be in the hatch lid area. It doesn't seem to be exhaust related. In all my adjusting, I have perceived a difference I think. Sometimes, I can get it to rattle by putting the car in gear and power braking slightly.(a certain resonance rpm just off idle).

Looking for any input.

 

I know you have stated that you don't think it is exhaust related but have you done any modification to the exhaust such a rear resonator removal? Maybe the previous owner if any?

 

I had the resonator removed then put back on. I had the suspicion that something might have came from it but it does not sound like its coming from the exhaust area. I've layed under the car while it was running and can not detect anything wrong.

 

You must be the skinniest man I've ever heard of .......

Seriously, does it rattle right away, or after it warms up ?
( Could be exhaust joints/bolts if the latter )

 

I had a rattle that absolutely sounded like the rear hatch. did all the fixes, nothing.
Didn't think it was exhaust related, but went through and re tightened all the bolts in the exhaust system and sure enough, the rattle was gone.
I'd re-check the exhaust and re-tighten everything.

 

When the car is cold, go take a look at the space between the rear muffler support bracket and the metal exhaust bracket hanging from the body just before the exhaust tips. Then run the car till it's hot and see how much the exhaust expands and moves backward. When it expands, my muffler bracket was making contact with the support bracket and it took me a loooooong time to find my demon rattle. It may not be this but worth a look.

 

I will double check the exhaust. It's hard to believe such a small rattle can drive you crazy. The rattle is not as bad as not being able to figure it out.

 

The exact bolt that SparkieSRT6 mentioned was quite loose on mine, and I suspect it was in fact the bolt that was causing the rattle. (I checked and tightend all my exhaust bolts, but that was the only one obviously loose)
It sounded EXACTLY like the rear hatch was rattling.

 

No BOLTs....the hanger I'm talking about is the rearmost muffler support brackets with rubber AMG donut.

 

Yup, I was unclear in my post, sorry. (one of) The rearmost bolts in the system was quite loose on mine, (the ones bolting the muffler to the rest of the system) allowing the muffler to shift around slightly and causing the same rattle from the hanger that you described.

 

Sparkie,
I went out and took a look at the space between the brackets on the topside of the muffler. With the car cold, the gap looks pretty close. Could close up when hot and make contact. I took some 3/4" heater hose and cut some spacers. Split the hose and wedged them on both sides around the edges. I also added a piece of rubber on top of the existing rubber mount in the center. Hopefully, this might be my rattle point. I'll let yall know. I would rather have bent the mount outward some but there is not a way to get a bar in the right place with the muffler mounted. If this temporarily fixes it, I will drop the muffler and bend the bracket.

Keeping my fingers crossed...

 

If this is it then I'd get the Muffler shop that re-installed the resonator to fix it. Good luck.

 

Have you been able to confirm the cause?

 

Sway bar broken loose?

 

Still rattling.........Got to get a few more ears to help with this one. Does appear to be worse when the car is warm, leading me to believe it is exhaust related. Probably going to run by the muffler shop. They are really good guys and will look and fix for free since they did the work last time.

I will update yall soon, hopefully it will be fixed.

 

Surely youve got it licked by now?

 

Yep, it is mostly fixed. It was the exhaust. The muffler shop bent the bracket slightly above the top of muffler. When hot the exhaust would expand just enought to close the gap to the point of causing the rattle. Sure did sound like the hatch. I do still have a very light rattle on occassion which I really think is on the passenger side of the hatch. I had backed the bumper off a little to much on that side. I just need to tweek it a little and I should be good. Its not very noticeable so I haven't been in a hurry.

One note to everyone, if you have had your exhaust worked on in any way and develope a "demon rattle", it is more than likely right at the top of the muffler and bracket. Very close tolerance from the factory, just a couple of millimeters expansion can get you a rattle.

 

New owner of a 2004 Coupe (30K miles!!). I had the rattle, too. Drove me nuts. Then, somewhere in a thread on the subject, someone mentioned wrapping the hatch latch (the part on the body) loop (hatch latch loop -- say that fast 5 times) with a few turns of electical tape. RATTLE GONE! Drove more than 100 miles today on all types of roads --- blissful, smooth silence. Worked so well I took it a step further --- replaced the electrical tape with a 1/2" piece of the loop side of velcro (softer, fuzzier side). Not only does it look better (tho' I'm the only one who would really notice), it works like a champ. Hope I don't get the muffler rattle syndrome.

 

I've recently developed a rattle, but I do think mine is something in the resonator. At least, that seems to be where the noise is coming from. I'm wondering if some idiot tossed a rock into my exhaust (I'm not the kindest person to bad drivers. especially those who sleep at stop lights or stop at green lights), or if perhaps a piece of the internal cat material. Wondering if it is possible to cut out a section of the resonator bottom, fish out what is in there and weld it back up. As an alternative, I've got a 79" parts grabber on the way, to see if it is possible to snake it down the exhaust into the resonator and grab what is there (I'm not an exhaust knowledgeable guy, or then basics). But, I'll also look into the hanger issue. But this definitely sounds like a rock bouncing around. Quite embarrassing, actually.

 

I had a noise like this once. After going crazy trying to find it, it turned out to be the most unlikely thing. One of the upstream oxygen sensors was loose. One turn with a wrench, and the noise was gone!