I bought an 87 535is that was not running due to a broken clutch pedal bracket so I don’t know if it was doing this before it was parked 3 or 4 years ago. I have it running now but I have no power steering and the pump is whining severely when you turn the wheel or press on the brakes, I got a pump from pick-a-part and had the same result so I bought a remanufactured pump from advanced Auto and I still have the same problem. As per the service manual I filled the reservoir and had some one start it and turn the wheels and pump the brakes while I added fluid to the reservoir until it was full and kept it up until the air was gone. The air bubbles never went away. The brakes seem to be getting a boost but not the steering. I’m thinking it may be the pressure switch, any way to test the switch or if the switch is getting a signal?