Have you cycled it a few times? Fill the tank, start the engine and turn the wheel back and forth a number of times, turn off the engine, refill the tank and turn the wheel a few more times. Repeat until the system is filled to the proper level with fluid. The pump will be noisy until you do this. If it is still noisy, make sure the belt is on properly and that the pump itself is not mounted crooked (pullys allinged). If the noise persists then you have a bad pump.