Rattling noise
 

When driving on rough roads, if I open the passenger window on my C30 I hear an annoying rattle.
I think it might be the heat shield, but when I look, it isn’t hanging off and the noise is more like a one time “tinny” bang, as though the heat shield is banging on the underside of the car.
I’ve taken it to my mechanic but he said he can’t find anything.
I can’t hear it if the windows are closed and it isn’t causing any issues with the running of the car and Volvo have done a vehicle health check and I’ve just had the rear suspension arms replaced as they were rotten but the sound persists and it just drives me crazy knowing its there and cannot pin it down.

Anyone know what it might be or experienced this before?

could well be the stabilizer end links. Really cheap to replace, however, this should also be pretty obvious for a mechanic, so I'm surprised they have not caught it if it would be the stabilizer links.

you can easily check them by getting off the wheel and wiggle the end links.

maybe a bad tierod end or ball joint in the front control arms?

Does the rattle stop when you brake? Worth checking it's not rear brake pad chatter.

Checked today, no noise when I apply the brakes no matter how rough the road is.

Stone trapped in the disc cover ?
Something in the engine under tray?
Broken front coil spring ?

Dunno what calipers you have, but on my V70 I can hear rattling with windows down, its the rear caliper anti-rattle spring (of all things!) which is past its best and is not snug against carrier, allowing caliper to jiggle about as it sees fit.