According to the power steering pump instructions, the system must be flushed and bled. After doing both of those things, the new pump whined on startup. According to the instructions, it may howl a little after installation. Two months later it's still the same. Very disappointed. Surprised that the pump return period for a brand new car part was only 1 month as most new parts have a 90 day minimum return period and most have a 1 year return period and higher quality parts are lifetime. I would not recommend or buy this brand of power steering pump again. I'm giving one star because you can't put zero stars.