There is some noise in all of the power steering systems. The most common noise is a hissing sound. The hissing sound is noticeable when you turn the steering wheel and the car is not moving. This noise will be most evident when turning the wheel while you apply the brakes. There is no relationship between the hissing noise and the steering performance. Do not replace the gear or the pump unless the hissing noise is greater than a similar vehicle that is operating correctly. A new gear and a new pump will also have a slight noise. A replacement is not always the solution for the condition.