A leaky windshield is a symptom of a poor contact seal at the windshield glass edge. Over time, anything from severe elements to an automobile accident can cause the glass to shift, breaking the seal. When this happens, water leaks into the cabin. The only way to fix this is to remove the molding around the windshield and reseal the glass edge.
Wedge the tip of the trim molding removal tool underneath the trim around the windshield. Pry up on the molding to remove it.2
Inspect the molding for any damage or wear. Try to locate the source of the leak. You may need to run a water hose over the surface of the glass near the glass edge to find out exactly where it is leaking inside the cabin.3
Trim back the existing urethane molding on the windshield with an automotive cutting knife. These are knives designed to cut urethane molding. (Your local auto parts store will carry them.) You'll want to make sure that you expose the area where the seal has broken and clean it up with the knife.4
Apply a fresh bead of urethane sealant to the affected area and allow it to dry. Drying times may vary depending on weather conditions, humidity and other factors.5
Insert the window molding. You'll need to force the trim back into place around the glass edge, pushing it down with the tip of the trim tool.