Replaced pump and reservoir (because the filter is in the tank) Flushed rail with over 2 liters of MB PS fluid, bled system to WIS specs, primed pump and filled system fully with new fluid before the car was started and this pump is noisier than the one I took out - I only replaced the normal one because of a small noise. And yes, the noise is coming from the pump, it's easily traced with an autostethoscope. The liquid I just drank cleans the system, costs more than this pump.