In many older cars the rubber door seals don't seal the way they should. Often the seals have pulled away from the door frame and leave gaps between the frame and the seal, almost always in the corners. This lets in cold or hot air, sometimes water and almost always excess noise. So many older cars have a noisier, drafty ride because the seals are not tight.
Many people think that the reason for the seals not staying in the frame is that they have come unglued. They will often try to glue them back in place but the seals will not stay there. That is because they are not glued in to begin with. The door seals are held in place by simple pressure. When the rubber seals get older the rubber shrinks, the older the seal the greater the shrinking. As it shrinks it pulls away from the door frame almost always at one of the corners. No matter how much glue you use you will not get the seal to stay in place because the seal is now to small to fit the opening. But there is a simple and very cheap fix for the problem that is permanent. You have to make the door seal bigger. Its a lot easier to do than you might think.
Step 1: Find the Seam Where the Seal Is Joined
The first thing to do to fix the problem is find the seam were the seal is joined. This will almost always be located under the plastic sill that protects the bottom of the door frame. Pry the sill up and off to get access. If yours is screwed down then remove the screws. Most have plastic connectors that go into holes in the floor and they are just pressed in place. They should pull up easily.
Once you have that out of the way you should see the place where the deal is joined. It will probable look like it has been glued or fused together. This is the easiest place to cut the seal. Most of these seals have a metal component running through them to make them rigid and cutting it can be hard. The seam has no metal so you can slice it through with a razor knife or a pair of heavy duty scissors.
After you have cut it you can push the seal back into the door frame corners where it is supposed to be. Sometimes it easiest to pull a section off and then start at the top pushing it back tight working your way back to where you cut it. Now you will be able to see how much your seal has shrunk.
Step 2: Add an Extra Piece
Find an extra chunk of door seal, a foot or so will do. You can get this from a junk yard or from another car even. You can also buy seals but they are expensive. I took a piece out of a a minivan that is used as a parts car. The best one to get is one that matches your car. If you can't get that then try and get one that is a close match. Door seals can be difficult to cut because of the metal pieces in it. I used a pair of tin snips to cut mine. Really heavy duty scissors might work also. A knife will only cut the rubber. A hack saw will work but its a little more effort.
After you get your seal material figure out how much to cut to fill the gap. First make sure the seal is pushed completely into the door frame. Next mark on your chunk of seal where to cut. Make it BIGGER than the gap by about a half inch. This way when you put it in place it will push against the rest of the door seal and help to force it to stay in place.
Push the piece you cut into the gap and hammer it down with your hand. You should not have to do it very hard. It goes in pretty easily. You don't need to use any type of glue since the pressure will and the sill cover will keep it in place.
Step 3: All Sealed Up, Now Do the Rest of the Doors.
After you get the filler piece in place put the plastic sill cover back on. Again just a hit with your palm should be enough to snap it in place.
And that is it. Your door seal is now tight and will stay in place for years until it shrinks some more. If, when, that happens just put in a bigger filler piece.
Now how come the car makers don't make seals so you can add spacers to them? It would be an easy source of income for them to sell DIY spacers that people could just pop into place and seal up their doors. Oh, wait, that would mean they would be keeping the cars until they were older and not buying new ones. Never mind.
Do this same procedure for all the doors of your car. If one has shrunk then they all have shrunk.
Enjoy the quieter ride.