Have a bit of a steering problem. Car steering works fine, except that when I turn the wheel to the right or left, a buzzing sound can be heard, possibly a running pump.not sure. Its not there all the time. When it is there it gets lounder if the car is stopped and I turn the wheel to one side or another.
Have you checked your power steering fluid?
beyond that, its one of those noises you have to either hear, or have previous experience with.