My 2007 Mercedes R350 makes a humming noise when I turn my wheel all the way in both direction. The power steering pump was replaced, but it didn't solve the issue. My belts are in good condition. Please help.

either you got a bad pump (ONLY use new ones, not rebuilt) or you need a new super expensive steering rack assembly

I bought a new pump. I did had a power steering leak and it was fixed.

Leave it alone, it’s the rack, not worth fixing