81 240D 315k miles
well i lost p/s about 2 weeks ago. sudden stop - pump was clearly not loading up when the wheel was turned. i removed the p/s pump cleaned and re-sealed it. no obvious problems in the pump, but lots of carb cleaner to remove the gunk - clearly neglected over the years. when i reinstalled the pump i routed the return line into a gallon bucket, jacked the front end off the ground, and had the wife turn from center to lock to lock while I added 3q of fluid. At the first lock i had a big gush of fluid into the catch bottle. the fluid was very airated - pink and frothy. once I stopped, topped off and test drove, no problem - p/s back as strong and silent as before. must have dislodged something in the box or unstuck a valve. now I have a nice clean pump and fresh fluid in the system.

if the p/s quits I would recommend a flush like this first before going any deeper. I might have saved myself a lot of hours. The flush only takes 10 minutes and you only need a phillips head, a gallon bucket and 3q of fluid.
happy motoring to me...