How do I troubleshoot water pump? With tension, serpentine runs off pulley. on 1997 BMW 740iL

Wife got stranded when she heard loud rattling noise and noticed coolant from under front of engine. Then we saw that serpentine belt runs off of water pump-fan pulley. When I put belt back on and re-tension, it runs 1-2 way off as soon as I start the engine. Possible for pulley to come loose and tilt down under pressure?

by in Potwin, KS on June 25, 2013
2 answers
ANSWER by on June 26, 2013
take to a shop an have it pressure tested to find the leak
ANSWER by on September 30, 2013
Replace Belt an Pully