If the sunroof is leaking in your vehicle, the only way to properly seal it is to replace the faulty seals. After you have inspected the car's sunroof seals to locate where the seals might have deteriorated, you can begin. Purchase the appropriate seals for your car model's sunroof at a local or online auto parts dealer prior to starting this job.
Draw lines with a permanent marker at the inner and outer edges of the corners and a dot where the seal begins and ends to mark the location of the old seal. This method will ensure you install the new seal in the correct location for a tight seal.
Start at where the two ends meet to remove the old seal. Gently pull up on the seal with your hands to remove it. Be careful if the seal is deteriorated and wear gloves or your hands.
Rub a non-abrasive adhesive remover to clean off any remaining glue residue from the old seal with a soft cloth. Thoroughly clean the area where the old seal was located and dry it with a soft cloth prior to proceeding to ensure the seal adheres correctly.
Peel back 1 to 2 inches of the paper backing from the new seal. Align the seal with the mark you drew where the old seal began firm press it down. Slowly continue working around the sunroof, peeling back the paper backing 1 to 2 inches at a time, to ensure correct alignment. Make sure the seal aligns correctly with the corner marks so it seals properly.
Trim off any excess seal, so that there is not a space and the two end pieces fit snugly together to keep out any moisture.
Carefully trim the seal so you do not accidentally scratch the car's paint.