Power Steering.

[Silver dude]

Or could be a leaky return line airating the fluid.

Guess I should of explained with more detail. When there is a leak on the return line the "suction hose". The fluid can suck up air thru the leak in the line. When air makes its way into the fluid it forms little air bubbles that suspend within the fluid. When these little air bubbles make it to the compressor they can't be compressed. So the rotors of the pump make a loud RAWRing noise as it crushes the air bubbles.

Other things it could be well worn fluid. A bad power steering pump. A worn or improperly tensioned power steering belt could be admitting noise as well.

 

[Haydenpete]

Power steering

My power steering was leaking so I took it apart and put it back together then when I put new fluid in it I ran it and it's all foamy and I can hear my pump wine also!

 

[Roadwarrior]

If you can hear the pump wine, and its foamy, you need to slowly pour more fluid into the resevoir. It sounds like you didn't burp the system and have a little air in it, causing both the foam and the whine.