The situation is most likely this, the drain in the
bottom of the wing window frame got plugged and the
frame is rusted out.  With the frame rusted out the
bottom pivot doesn't have any support and won't allow
for enough pressure to seal the wing window to the
seal.  The fix is to replace the frame/ pivot/ seal as
a unit.  The frame is a shade over a $100.00, the
pivot is around $50.00 and the seal is around $30.00.
Also, if you chose to get a new frame you will need to
buy the correct rivots to reattach your upper wing
window pivot to and find the correct tool to get this
rivot squished (or just find a not rusted out junk
yard frame with this pivot attached).

Since I am facing the same issue I have found that a
strip of foam weather strip in the 1/8 thickness
applies enough pressure to the seal to stop the
whistle and the rain from coming in.  The draw back of
course is that you can't open the wing window or the
seal will come loose.

I will let you know how it goes since I have all the
above listed parts and have been too busy to finish
the job.

Brian from Salem, Or

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