To save me chopping one up to have a look does anyone know if there are any moving parts inside one of these?A car I have been working on recently(s4) makes a bizzare sound intermittently and the noise comes from somewhere down that way(bottom of bulkhead/drivers door hinge area).The noise sounds like air passing a valve of similar,if you feather the throttle you can change the pitch of this noise,usually only lasts a second or two.It only happens when the car is moving btw