I have water leaking in to my hatch on the passenger side. The weatherstrip is new GM replacement. The leak is occuring right where there is a plastic "tab" of sorts bridging a gap on the underside of the decklid. I tried taking off the tab and filling the area with weatherstrip adhesive, but it got worse.

Has anyone fixed this? I can't imagine how water is getting up there to begin with, and the shop manual is not much help with this area. Is water getting in between the hatch glass and the decklid on top?

 

Yes, the water will be coming inbetween your decklid and back window.

 

Best way to fix is by lifting the deck away from the glass.Apply some RTV silicone or ?.Just make sure you have a good thick bead across the width of the glass.