fix for rear vent noise
 

I have an '87 coupe (non sunroof) that I had alot of traffic noise in the cabin. I searched this board and found that the cause of this was missing foam pads in the rear roof vent. I came up with the solution of inserting an inflated 1" bicycle tube into the vent. The vent is 25 3/4" long and is about 3/4" high inside the cavity. The 11 vents are about 1/4" high. The first picture shows some of the materials I used.http://forums.pelicanparts.com/uploa...1275881123.jpg After you cut the tube to length clean it with laquer thinner. Clean and sand at least 1/2" of the inside ends so that the hot glue will adhere. Glue and clamp one end of the tube shut. Next, blow up the tube with your mouth then clamp it shut close to your lips (go on start laughing). With the tube inflated apply glue to the inside of this end and clamp with a second clamp. Release both clamps after a few minutes and the tube should be holding air. Tie 4-5 pieces of string around it. These will help you control it when you slide into the vent. Try to space them so that none are behind the vent uprights.
The finished tube is shown in this shot.http://forums.pelicanparts.com/uploa...1275881717.jpgNext thread a length of string through the rear vent as is shown here.http://forums.pelicanparts.com/uploa...1275881868.jpg
Tie one end of the tube to this string and have a helper pull it into a slot at one end of the vent as you feed it in. Once it gets going it slides in pretty easily. Use tweezers to draw the string through the slots and pull the tube to the rear of the car. You can use thin dowels to move the tube a little laterally.http://forums.pelicanparts.com/uploa...1275882192.jpgOnce you're happy with the position use tweezer and a razor knife to carefully cut the strings and pull them out of the vent. I was thinking about gluing the tube to the vent uprights but decided that I may want to remove it later should it fail. The finished product is shown below.http://forums.pelicanparts.com/uploa...1275882437.jpg
Before I started I checked the source of the traffic noise by taping over the vent with 1/2" x 1/8" foam tape and decided that this was in fact he problem. The tube I inserted is almost as effective at reducing the traffic noise and looks a lot better. Thanks for the guys an this board that identified the problem in the first place (I was about to start replacing door and window seals.

I read somewhere that there is high airflow in a Porsche to keep fresh air in the cab if the heated air is contaminated by carbon monoxide caused by leaking headers. so be careful on how sealed you make the cab. I know mine leaks and I keep the windows cracked when the heat is on.

I have seen pictures of 993s that appear to have a piece of something or a spoiler of sorts at the top of the rear window that looks like it might block off that vent or at least clean up the air flow from the top of the window/back or roof area. Does anyone know what I'm talking about?

Yes it covers the vent on the top but the bottom is open. you can get a brake light in there also.

like one of these?
http://forums.pelicanparts.com/uploa...1275892684.jpg