clk mystery rattle

[howardfromsydne]

I have just bought a W209 clk 240 coupe ,2005.
Fabulous, my first MB
But the rattle!
Somewhere in or near the rear parcel shelf.
It's driving me nuts.
Sounds like a small metallic part vibrating quickly on metal or plastic.
And intermittent. Some days not heard, other days always there, but especially on rougher road surfaces.
I thought it might be a speaker retaining screw, a seat belt fastening, a loose clip in the rear parcel shelf or a cable thats come free from a retainer. Can't find it. Anyone had similar?

 

[GP801]

Try checking the warning triangle. This rattled on ours and the noise travels.

 

[BillyW124]

hard to distinguish sound,

i might be way off but could it actually be a subframe mount/bush?

 

[howardfromsydne]

Thanks for the suggestions.
I had a friend ( a professional sound man) sit in the back seat with his directional microphone and headphones and he reckons the sound emanates from the middle of the parcel shelf where the back windscreen meets the boot lid.
So working on the possibility it is the safety triangle, which is only centimetres from there, I have gaffer-taped the whole assembly and it's retaining bracket, and I'm now looking for rough roads to test the repair.
Again thanks for your tips.

 

[x332race]

Had a similar problem with my c-class...tried everything including removing the jack, triangle etc, gaffer taping anything that could possibly move......in the end it turned out to be a rear shock absorber that was on its way out. Had both the rear shock replaced and no more rattle!

May be worth looking at?