A rusted windshield frame is dangerous because the integrity of the frame is compromised by the rust leading to corrosion and structural damage. The sooner you deal with a rust problem, the easier the job will be. Rust develops gradually, and, the more severe the rust, the more difficult the problem. The major headache in dealing with a rusted windshield frame is the windshield itself. To thoroughly remove all the rust on a windshield frame, it is necessary to remove the rubber seal and the windshield.
Determine if you want to remove the windshield yourself or have it professionally removed. Removing it yourself is more cost-effective, but it is a delicate procedure. Removing the windshield is an essential step in dealing with the rust around the window frame. Remove the windshield wiper arms. Pry the rubber seal loose with a pry tool, and pull it free from the windshield. Cut the urethane seal around the perimeter of the windshield with a utility knife. Push the windshield out of the frame, and store it in a safe place.
Clean the windshield frame with detergent and warm water.
Scrape the loose rust off the frame with a wire brush. Sand the rusted areas on the frame with an oscillating sander. Use 60 to 80-grit sandpaper for heavily rusted areas and 120 grit for less severe rust spots. Continue sanding, until the bare metal is exposed.
Wipe the frame with a clean cloth and denatured alcohol to remove all traces of grease and other contaminants.
Repair minor holes and damaged areas with Bondo. Apply the Bondo with a putty knife, and allow it to dry and harden for 45 minutes. Sand the repaired area with 120-grit sandpaper, until it is smooth and even.
Apply several light coats of automotive self-etching primer to the frame. Hold the nozzle eight inches above the frame as you spray the primer. Allow drying time in between coats.
Apply several light coats of rust-inhibiting automotive paint to the windshield frame. Rust inhibiting paint is available at local auto parts stores.
Replace the windshield and rubber gasket on the window frame.
