Hey guys, I keep hearing this 'hum' noise in my car...it sems to happen a lot when I turn the wheel, usually to the right, and sometimes if I pop it into neutral it will go away, sometimes not, and sometimes it will come on at random, as I'm going down the road...it didn't used to happen as much as it does now that it's colder outside; I don't know if that has anything to do with it or not. One of the guys I work with was riding in my car and I was telling him about it and he heard it and said that in his old Contour (a 95) he had a very similar noise. Took it to the dealer and got it and something else fixed. He thinks it might have been a vacuum pump of some kind, but he's not sure. (He isn't a real car guy, he's a computer geek like me...hehe). If this is the problem, is it difficult/expensive to fix? Is it going to require a dealer visit??

Thanks!