Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
your issue is not uncommon ... its a weather seal failure, theres "mastic" (sealant) inside the liftgate weather seal, this "sealant" is to fill the seams where the different metal parts come together at the liftgate opening ... best way to fix this is on a warm day, pull back the liftgate weatherstrip and apply a product called "high tech seam sealant",its a product developed by KENT industries #10200 available at many auto parts stores. This product stays flexible and is fluid enough to flow in between the metal seams. Repair procedure ... Pull back the weather seal, apply a bead of high tech sealant on the metal flange edge and push the weatherstrip back on the flange * only do half the liftgate weather seal at a time.
I hope that i have provided the information you were seeking. If you are satisfied with my service please use the required rating for me to receive credit for working with you.