My power steering pump has just started to make a faint rumbling noise and the fluid is brown and foamy. I changed the fluid and the new fluid became brown and foamy also. I also feel a slight difference in the steering wheel power assistance. The pump and the steering box have no leaks and the belts are at the proper tension. It appears that it's sucking air. Has anyone had this problem? I think I may have to replace the pump but I'm also looking for some input.

Ben