DIY sliding window leak permanent repair

Leevon · January 15, 2022

This is my 2nd Trail Boss with a leaking slider, both of them I bought new. The first one I fixed myself by replacing the slider with a solid window (details are somewhere in the massive leak thread). The second one I wanted to keep the slider and permanently seal before it ever leaked. I've had the truck over a year and finally got around to it. Since I was dropping the headliner I also added the camera rearview mirror and hard-wired my radar detector.

I dropped the headliner and removed the spoiler. I cleaned the top of the window channel with all purpose cleaner and a detail brush and dried it. I taped the top of the glass and back of the cab with some little tape ball dams at the ends. I warmed the area up with a heat gun so it would flow then I applied self-leveling sealer SEM 39387 then I hit it with the gun a little more to draw out air bubbles. After that cured, I put 3m strip caulk on all of the spoiler bolts and nuts and re-installed the spoiler. The self-leveling sealer had the exact effect I wanted, it bridged from the glass to the body and covered up the plastic slider frame that cracks and leaks. There were no cracks in the frame this time. I also noticed they are putting a little sealer on the nuts that hold the spoiler on, but it's not adequate. The way I did this it should never leak from the glass or the spoiler holes.

The mirror upgrade was easy, swap the brake light, add the cable and swap the mirror. Plug-and-play.

reeseb · January 15, 2022

Nice work and great detailed pics!

DaggerEnterprises · January 15, 2022

Very nice work and detail, I am planning to do the same on my 2nd truck since the 1st one was destroyed by the dealer and GM did not care one bit...your detail makes it that much better!!!

rbdjr · January 16, 2022

I have my fingers crossed, 2021 RST 4x4 crew, slider no leak yet? all good, manufactured 6/21

fatwhiteboy · January 16, 2022

Thank you for the detailed description and pics. That headliner looks like a real pain in the backside to drop.

smit303 · January 17, 2022

Nice job. Still can't believe we have to do this stuff to make it right. My 19 Denali leaked shortly after I got it. The dealer did the repair It it hasn't leaked since. I just ordered a 22 Denali. Hopefully, they have fixed the issue.

Jay P · January 17, 2022

Great work/write up. Someone needs to pin this so it's easy to find/see.

Jay

newdude · January 17, 2022

On 1/15/2022 at 5:22 PM, Leevon said:

I also noticed they are putting a little sealer on the nuts that hold the spoiler on, but it's not adequate. The way I did this it should never leak from the glass or the spoiler holes.

The mirror upgrade was easy, swap the brake light, add the cable and swap the mirror. Plug-and-play.

I hope you got new nuts before you put it all back together.

Quote

18-NA-383: Water Found in Rear Interior of Cab, Water Leak at Rear Sliding Window - (Oct 23, 2020)

Important: The 8 central roof spoiler nuts are NOT reusable fasteners. The original fasteners must be discarded and replaced.

Allow a short time for the sealer to develop a skim coat, then reinstall the spoiler and headliner. Refer to Roof Rear Spoiler Replacement, in SI.

Allow at least 24 hours before running the truck through any car wash.

Leevon · January 18, 2022

On 1/16/2022 at 1:06 PM, fatwhiteboy said:

Thank you for the detailed description and pics. That headliner looks like a real pain in the backside to drop.

You know what it's not too bad, I probably had it dropped in about 30 minutes. It re-installs in 10 minutes. It is the second time I have done it so that was a huge help. And there is a video from infotainment.com that is outstanding I used as a refresher. I promise something WILL break though, you just have to accept that, there are too many plastic pieces being touched. I'd rather be the one doing the breaking though. The "A" clips that hold plastic trim on are always terrible. For me this time it was one of the clips that secure the headliner around sunroof. No biggie.

Leevon · January 18, 2022

20 hours ago, newdude said:

I hope you got new nuts before you put it all back together.

NO, unnecessary. The bulletin is BS. The reason why they want that is because the updated nuts come with a "teflon-ish" type thin seal (see the white stuff in my photo). The seal is completely ineffective. First off it's on the inside of the cab and second they don't make an adequate seal. Third they're $37 for new nuts lol. If the engineers had their heads screwed on they would be recommending something like what I did. I wrapped each spoiler bolt (8) in 3m strip caulk at the base and each of the spoiler nuts (4) on their flange. When the spoiler is installed this sandwiches the strip caulk through the holes, creating a permanent seal 100x better than the factory. Another fault with the design is that there are supposed to be thin seals on the spoiler side of the holes on the posts. I found (1) total on my first truck and (2) on the second. There should be 8, they simply don't get installed at the factory. I take them off before installing the strip caulk.

Edited January 18, 2022 by Leevon

Leevon · January 18, 2022

Since this is now a sticky, I hope the mods don't mind me posting the video you can use to get comfortable dropping the headliner. It's from a vendor that sells the camera mirror upgrade as a kit, I have no affiliation with them but I think the video is a great help.

Leevon · January 18, 2022

Also, here is what you're trying to fix, small cracks in the plastic slider frame that allow water to pass through:

dgoins816 · January 22, 2022

Very cool and detailed account of how to remedy. My 19 had this issue as well - of course it cropped up right when we were getting very heavy rain here in Indiana.

Mad Max · January 29, 2022

On 1/17/2022 at 12:40 PM, smit303 said:

Nice job. Still can't believe we have to do this stuff to make it right. My 19 Denali leaked shortly after I got it. The dealer did the repair It it hasn't leaked since. I just ordered a 22 Denali. Hopefully, they have fixed the issue.

I just purchased a new 2022 Denali Limited and was checking out this thread for insights should I have a leak. Is it just me because I can’t find a forum for my 2022 truck here? Did you get a 2022 limited?