Do you have fluid in the resevoir? Have you changed it? If it is making alot of noise, then it maybe the pump. My wife's e46 325 went out and it wasn't too hard to change.

The drive belts connect to the water pump, alternator, and power steering pump. The AC belt connects to the compressor.

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95 M3
03 X5 3.0
06 X3 3.0 Sport