Hi,

My 2004 S Type has an incredibly irritating intermittent interior rattle. It's not the bushes or anything like that, it is just an interior rattle that is ruining an otherwise perfectly silent driving experience! It sounds like it's coming from the rear shelf behind the back seats but after smacking, applying pressure and all the usual tricks it doesn't help.

HOWEVER... there is a twist in the tail!!

If I drive at motorway speeds with all windows and the sunroof open, the rattle seems to go away temporarily after I've closed all the windows, then after around 50ish miles it'll come back.

If anyone could point me in the right direction I would be eternally grateful!

 

Have someone (a SO or friend) sit in the back and go for a drive(?).

 

Only "moveable" items are the fold-down rear seat backs, which could latch loosely; the 3rd brake light assembly rattling against the window, and possibly one or more of the plastic child seat clip covers on the rear deck.

You might consider removing the back seat bottom and inspect. It is NOT fully carpeted, and there are 2 fuel pump wells that could have a metal object laying in there just waiting to annoy you.

Also check the rear fender wells. Are they secure? My front ones were missing the lowest screw, which would rattle on a mild speed bump.

 

Interesting observation. I wonder if the rattle has anything to do with normal ventilation through the cabin. When the AC or heater is running, you're pumping air (at a very low pressure) into the cabin. If there was no exit vent, airflow would quickly slow way down and the cabin air would get very stuffy. Here's a very vague description from a student guide:





Based on that, it seems the rear doors (or jambs) have some sort of exit vents in them. Look those over carefully for evidence of blockage. If blocked, perhaps the lightly pressurized air is finding some other way to escape, perhaps into the trunk and then out past a loose trunk seal or via the battery vent.

To test this idea, unlatch one of the rear seat backs and prop it forward a couple of inches. Now any airflow will have unrestricted access to the trunk. If the rattling ceases, I'd suspect the rear parcel shelf was part of the rattle equation, such as a loose speaker.

 

One thing I forgot to mention....when the vent system is blowing air, some is routed through the console, and to plastic vents in front of the rear seat. I had one disengage from the vertical control knob, which would on occasion, give me that plastic on plastic rattle. Pried the assembly out, and corrected the knob control problem.

 

the actual vent exit is behind the audio stack , it exits to under the left rear pumper panel .

i had an annoying rattle a while ago that went away by putting the peasant blocker/sun blind
up.
one of the motors was rubbing against the parcel shelf . some underlay had bunched on refitting .
and was an easy fix .
does this car have a peasant blocker ?