So I have a 2007 s40 AWD type R. It slowly developed this rattle that almost sounds like something is rattling against the bottom of the car on the passengers side floor board. Everything seemed tight on the front end but the bushings on the back of the control arms looked worn out and sounded to be a common source of rattles. So I replaced both lower control arms. Exactly same thing. So then I thought it could be the wheel bearing, replaced if.... same thing. I also left the car in 1st with the engine off and tried to rock the car back and forth to see if the engine is moving. Which it doesn’t appear to be. I currently have it jacked up and only see one exhaust hanger pulled off (near the rear end. None the less here a video of the noise.

 

That sounds like loose exhaust rattle.

 

Is there a common place that the exhaust would rub the body ? Or a cause such as a bad mount?

 

Not necessary a mount but it could be a broken flex piece or a rusted muffler.U would go under and keep tapping the entire system to see if i can reproduce and pinpoint where it comes from.

 

It does sound like an exhaust leak in the video however in real life... It sounds like its hitting the floorboard of the car.

 

You may have already checked this...I found a similar clunk due to the plastic skid plate being loose after an oil change.

 

The main motor mount on the pax side has also been known to split in two which causes a clunking sound as the now loose halves bash each other.

 

 

I once found a rock stuck between an exhaust shield and exhaust. Made the most awful rattle. Lesson for me is look for the simple stuff first.