W126 380SE Rear Window Leak
 

Car is in great shape, no rust around window or anywhere else for that matter (southern car). When purchased, it came with a used window and brand new seal sitting in the trunk. There was no leak at the time, but the rear window was hazy in the corners, so the PO had purchased these but never got around to installing them. I called in the phone book and located a guy who would install the window and new seal for $85.

I drove the 300E to work and the auto glass guy came out that day to do the work at my house. When I got home, my wife said the glass was replaced, only problem is the guy did not change the seal!!! I was miffed, but according to him he does this for a living and in his experience the existing seal was in perfect condition and did not need to be replaced so he didn't replace it. The problem now is that with all the rain we have been getting here I now see visible seeping of moisture on the driver's side. It's not exactly running, but it's definitely there and it's on the inside.

I called the auto glass guy and told him about the seepage. I also reminded him how I asked to have the seal replaced but he didn't replace it. He told me replacing the seal will not help the leak, that it needs to be sealed with a sealant which he will do for me. Despite my contention that the old rubber has been in there for 21 years, he insists there is no need to replace the seal.

Experts please chime in, as I have done a search and none of the threads address age of seals causing leaks, especially when there is no rust present.

Should the seal be replaced? Is the job way easier or quicker if you leave the seal intact or something? I can't figure out why he wouldn't just replace the seal like I asked him to. Is this guy just yanking my chain? What about using a "sealant" to stop leaks? How is that different from me using a tube of silicone caulk?

I have heard there are replacement seals of varying quality, and a bad one will leak more than the one it replaced. I would check on the source of your new seal before insisting it be installed.

You can also run a bead of black marine grade sealant around the whole perimeter, glass side and metal side, but leave a section of rubber-to-metal unsealed along the bottom to allow for drainage.

If your aluminum trim around the window is still in good shape after the job, I would say he knows his stuff. But I would still question his decision, since its the same amount of work to reuse the old seal.

Thanks for the input. I'll have to check again when I get home, but I think the seal was OEM. It is brand new and unopened. It seemed to me that if someone was going through all the trouble to remove the window then they might as well replace the seal too. All the trim is still in great shape, for what it's worth. I'm supposed to swing by his shop on my way home Wednesday to get this resolved; I'll report back.