High pitched rattling/ringing at idle

[TheBigUnit]

Hello all,

When I started my 2007 Cooper S this morning there was a low rattling from the below the car, that sounded like the flywheel. Before too long it passed, but since then, when ever the engine drops to an idle it emits a high pitched rattling/ringing noise, that is very noticeable inside and outside of the car.

Has anyone else experienced this? The car is booked to go in on Thursday, and they have scheduled a drive with the master technician, but fore-warned is fore-armed and all that.

Thank you in advance.

[TheBigUnit]

It was actually the water pump. When the engine was warm it was working harder and that is why the noise became higher and more audible.