BMW: Water Leak, rust hole, 325is

Question
Recently had a thunderstorm. Found that the passenger side of my 325is ('90) was full of water. I know it's coming from the outside vent just below the windshield. What can I do?

Answer
Albert,
 If you are talking about the vent beside the wiper arm, then this is a common problem.  It's obvious that water can get in this vent when it rains, so BMW designed a drain in this vent.  Most of the time the leak is because of the drain getting clogged.  Those vent covers just "pop" off, so you could take a water hose and spray out this vent to possibly dislodge the blockage.  Sometimes when this drain gets blocked, water will sit in the cowl and finally rust away, leaving a hole(s).  If you clear the blockage and are still getting leaks, you probably have a small rust hole that is letting the water run down that way.  Try to locate the hole and close it.  if it's a small hole you could use silicone or some other sealant for a good fix.  If it's a large hole, you might have to replace some metal to fix it right.
 Good Luck!
 Josh