Replaced Rear Window Gasket
 

Yesterday I bit the bullet and replaced the rear window gasket myself on my 300D. I had found someone to do the job for $75 but with no guarantee against breaking the glass. So, having done two windshields (on little Triumphs) I decided to attempt it.

Well, I did it without breaking it, but I must have bent the aluminum trim taking the old rubber out because it doesn't sit quite right. I'm not sure I got rid of the leak, but I feel a lot better because the old gasket was a mess! And I understand the concern about that glass because it is real thin. I thought several times I was going to break it but I was lucky.

The good (?)part in doing it myself was that I caught some rust starting under the gasket before it rusted through. Other than that, it wasn't worth the effort, as it took me ( I am slow) about 7 hours of not-so-fun work. But if you do have someone else replace it, my advice is to ask up front what they will do if rust is encountered. You want to be sure it will be fixed, and have some idea what that might add to the cost.

I suppose there are a lot of methods for removing the old glass, but when I watched an installer replace my windshield I saw something very interesting in his method. He actually took a knife and cut the old gasket in half before he ever removed anything. This prevented the bending of the moulding and allowed him to easily pry the cracked glass out without damaging it anymore than it was, even though it was no longer usable. I think the latter was more "show" for me than it was anything else. He could have just as easily gotten inside the car and kicked the glass out after cutting away the gasket and lifting off the moulding.

On the install, he completely assembled it with moulding and everything outside the car, sprayed the gasket down with silicon, laid it over the opening and "slipped it back in". The latter was pretty neat because he'd taken some parachute cord and made a couple "wraps" on the inside of the gasket, laying the end of the cord inside the car. After laying the assembly over the opening he took the cord and started "unwrapping the cord" which pulled the rubber inside the window opening. A couple jiggles here and there and it was a perfect fit.

All-in-all a pretty nice technique.

I think I bent the moulding because the gasket was just SO rotten looking I figured it would slip right off. Well, it took a little pulling and, although the side/top pieces are pretty beefy, the bottom rail is wimpy. I rebent the bottom piece before the install to follow the curve of the bottom channel. I guess I just thought I didn't warp the side/top pieces but I was wrong on the right side anyway. Probably should have cut the gasket from the inside and popped the whole assembly out. Well, next time..

Cutting the gasket is by far the best. The trim is aluminum and very easily bent.

The cord "trick" is actually the proper method of installation. A little practice and is really quick. Not a one man job, though, much easier with two.

The paint needs to be in good shape under the seal -- sand any rust you find, coat with coversion primer, then standard primer and finish coat to match paint, then let is stand at least 48 hrs if you can before installing the gasket. If you have any rough spots, the gasket will usually leak, and any bare metal will soon rust.

Peter