HELP! What's this? It's making noise...
 

http://lh6.ggpht.com/_Bezc4KNud5Y/TB...ompartment.jpgHi all,
So when I turn of my s40, this thing (circled in red in the picture) continues to make an unhealthy sounding winding down noise for awhile and then stops. Is it related to the fan?....should I replace? Expensive?
Thanks all!

It is related to the brakes, an aux. pump.

does it run continously? it should run when you hit the brakes, even with engine off. pos 2.


let me know if it runs continuously.

First of all, thanks for the quick response, much appreciated. Unfortunately the car is in NY right now and I'm in DC but basically I got in the car, pressed on the brake and turned the car on. Then I decided to look under the hood (not for any particular reason, sound etc just to look under the hood). I turned the car off, popped the hood and heard that thing winding down in a smooth manner, not on and off. After maybe 20-30 seconds the sound came to a stop....perhaps that's normal? I guess it just surprised me because I thought that only the fan would be winding down (it was silent, I guess because I had only just turned the car on)
Thanks again

It probably is normal, but if it has a problem, it will set a check engine light because it will burn up running too long. keep an eye out, there is a switch, in the hose connected to it behind the battery that fails. In the pic., the hose is to the left of the master cylinder.