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Check to be sure the drive belt is still on there, but typically these have issues with the powersteering pumps. You would need to take a fluid pressure test to further verify this, however, you can use a turkey baster to remove most of the fluid out of the pump. When the fluid is low the pump should make a girgling sound, indicating it is trying to pump fluid. If no sound is heard, the pump is not pumping. Also, if the fluid is low, add some and see if the power steering comes back in, if so, then the problem is due to a leak, possibly behind the pump or the high pressure hose.
Lead Technician
BMW Factory Training, ASE Master Techinician, Advanced engine performance.
The resevoir looks like the one below, the pump is run by the drive belt and is mounted to the front of the engine.
Yes, both components are under the hood.The resevoir is not attatched to the pump, it is mounted to the side and on top of the enigne. The pump may be difficult to see, but the pulley is the most noticable part under the belt. Below is another pic to better help you.