Following are my experiences with removing and replacing the rubber seal on the rear window. This is a common problem with the W126. If water is collecting in the trunk, look under the glass for any rust spots. If there is water leaking from the corners of the glass, the seal is leaking. A second sign is a "foggy" appearance in the corners of the first-generation back glass. This is the result of the glass delaminating. You can use this as a companion to the FSM.

Gen 1 or Gen 2 backglasses may be used. I got one from a junkyard from a 1991 W126. BEFORE REMOVAL, DISCONNECT THE BACK GLASS HEATER STRIP!

With a utility knife, I removed my back glass from the inside. The glass should pop out easily. What I found was severe rust.

Fix the rusty channels as necessary. Mine was wirewheeled and treated with POR15 rust remover. I chose the composite approach. It was coated with POR15 and reinforced with fiberglass cloth and thickened POR15. Then, it was primed with POR15 primer, and smoothed with Bondo fiberglass strand filler. It was sanded down, bondoed with bondo gold filler, spot filler, primer, basecoat and then 2k clear urethane spray.

Under the window, I brushed on Loctite rust reformer. I then sprayed the underside with CRC Marine corrosion wax.

Attached Thumbnails

         

__________________
Theseus

Instragram: doss_project
1984 300SD - 930 Blue, OM 617
Murfreesboro, TN

Theseus owned a ship in Greek mythology, and when a part of the ship needed replacing, it was replaced. Eventually, everything was replaced. Is it the same ship? (I own the car of Theseus. )