Leak in back of cab

[memheli]

I posted awhile back on this, but did a terrible job of providing useful info, and humor.
I've found significant moisture/water in the tub under the rear seat/driver side. Items in there were soaked. I can also see some rust on the back of the seat structure.

I've since decided that my third brake light gasket might be the culprit. I'm headed towards replacing the gasket. Two questions.

Is the gasket a compress fit to the fixture, adhesive to the body, or do I also need some type of sealant to be back to or better than factory?

Should I also be considering a light replacement. I've seen some in a quick search that were roughly twice the price of the gasket.

 

[FN-2187]

I used a factory gasket along with a bead of clear sealant along the outside perimeter. It fixed my leak I was finding in my passenger side footwell area.

 

[CoronaRaptor]

There is no factory sealant and there is a small opening in the bottom of the lens to allow moisture to get out. Don't seal that up or condensation will have to way of getting out.

 

[FN-2187]

There is no factory sealant and there is a small opening in the bottom of the lens to allow moisture to get out. Don't seal that up or condensation will have to way of getting out.

welp, learned something new. i guess I'll have to go check mine now.

 

[nec9]

I just went through a carwash and noticed some water droplets on the back seat headrests looking like it came from the sliding rear window. Now I'm wondering if its this...

 

[Jakenbake]

Funny, I have noticed my sliding rear window is leaking as well. Supposedly TSB 13-5-15 is supposed to address this.
I saw a screenshot of some directions and it is called “F150 center slide glass modifications”.

Supposedly part number for the seal kit is AL3Z-15262A80-A. You also use some sealant in one area too.

I have not verified any of this yet myself, but I did remove my lower seal strip and noticed it was about 1-4” to 3/8” shorter than the opening it was sealing. So I am also going to look into if a new seal is available.

I did find that the aluminum channel that the window rides in has a weep hole and is intended to drain some water that makes it past the seal. The weep hole drains outside the cab.

 

[RaptorFun]

Water intrusion could be coming from the third brake light...defective gasket. Had it happen to me. Found water droplets in the same area.

 

[Jakenbake]

Can anyone confirm that their lower seal strip for the sliding window looks like this? I have about 3/16” on each side that allows water in.

 

[Jakenbake]

Nobody wants to take a photo of their back glass?

 

[nec9]

I can confirm i dont have those gaps.