A noisy power steering pump can be caused by many things. Power steering pumps operate at very high pressure and should be serviced in accordance with the manufacturer's recommendations. A failing power steering pump can present various noises, from squealing to groaning. Also, you may experience steering that is stiff or slow to respond. If you're experiencing any of these symptoms, call S And S Inland Star Mercedes in Highland at 909-864-4701, or schedule an appointment online.