Rubber window seals on a car generally receive little consideration, at least until they begin to crack and break. They’re vital for keeping wind and water out of your interior, so if there’s a problem, they need to be replaced. It might seem daunting, but it’s actually quite an easy job, although it does require patience to do it properly.
Step 1 - Remove Old Seal
Start by opening the car door, as this will give you more freedom of movement around the window. Locate the spot on the seals where there’s damage and gently ease the head of a flathead screwdriver under it. Very carefully, move the screwdriver along to separate the rubber from the metal. Once you’ve loosen enough of it, you should be able to peel off the trim. It might break as you do this if it's especially brittle; in this case, begin again with the screwdriver until you’ve removed all the seals.
Step 2 - Clean
There will be residue of rubber and adhesive where you’ve removed the seals. Before putting in new ones, you’ll need to clean all this off. Start by applying solvent to get rid of most of the debris, and then rub hard with a rag to take off as much as possible.
Once the cleaned area has dried, use automotive cleaner for anything that remains, scrubbing all the way down to the metal. Dry afterward with paper towels.
Step 3 - Sand
Now you need to sand the metal so the new adhesive will stick. Be very careful here. Use very fine-grit sandpaper, rubbing in circles, but don’t sand the area beyond where the seals will lay or you’ll ruin the appearance of your car. Once you’ve completed this task, dampen a paper towel and wash off all the dust thoroughly.
Step 4 - Apply New Adhesive
You’ll need to put down weather stripping adhesive in order for the rubber seals to remain in place. First, however, you will need to cut them to size and dry fit them to the window. Only after can you apply your glue. Put a thin layer where the seals will sit on the metal, and while it begins to dry, apply a bead to the inside of the rubber itself.
Step 5 - Put New Seals in Place
Give the weather stripping adhesive about 10 minutes to become properly tacky, and then begin to fit the new window seals in place. Go slowly, pushing down firmly as you go. This will ensure a firm bond and also expel any air trapped between the rubber and the metal. Squeeze along as you move.
Once the new seal is firmly in place, go around once more, pressing down on the rubber. This will not only take out the remainder of the air, but also ensure that the seal between rubber and metal is tight and remains that way.