I too have a 2007 E63 and I replaced my pump when I had the heads off ( much easier with Head off! ). Months later when I finally had her all back together, I couldn’t help but notice a loud whining sound whenever I would turn the wheel. Mind you, I refilled the Fluid after having removed the HP Hose to get that rebuilt. I did the prescribed (engine off) lock to lock 30+ times, but the didn’t seem to work!

What did work was getting 4 bottles of fluid, disconnecting the return hose, attaching a clear drain hose to it attached by clamp to a bucket (having a small 6-8 mm socket served as a joiner to both hoses with stay ties wrapped around each side). You’ll have to attach a nipple end fastener to the end which connected to the return hose to keep fluid from spilling out. Then you fill up the reservoir and then turn lock to lock, as you do this the fluid will be expelled from the steering rack while new fluid from reservoir is being sucked into the rack. Be sure to constantly fill up the reservoir while you are doing this being sure to allow the air bubbles from pouring the fluid into the reservoir to dissipate before turning the wheel lock to lock. You don’t want those bubbles being sucked into the rack! While turning the wheel lock to lock notice the color of the fluid. Mine was pretty dark until I I saw it turn lighter. I also noticed that bubbles appeared in the hose towards the end after 3 bottles of fluid! I kept bleeding until I saw no bubbles. After doing this, mine turned out much quieter. You’ll then have to reconnect the return hose ideally using the proper Oedecker Clamps.