Windshield problems of the 2004 Chevrolet 1500

Venture van. On the first day owning the vehicle windshield made a loud whistling sound at highway speeds. The dealer has had it 4 times, and replaced the sealing material, but it still whistles. It is loose, and a safety hazard. The service manager says there is something wrong in the epoxy sealant that was installed at the factory. Some sealant was added to the center top of the windshield, but it still whistles. On the 27th, after the new windshield and sealant was added the windshield blew out at highway speeds.