Rear window leak

Jrodpic · November 22, 2020

On 11/11/2020 at 5:27 PM, Jrodpic said:

Found something that works to seal up the top gap of the spoiler. I just got done installing it. Just need something thin and plastic to work it into the gap. Can’t guarantee it will fix the leak, but for $15 is worth a shot. Will report back.

https://www.amazon.com/gp/aw/d/B00NL4D2T8?psc=1&ref=ppx_pop_mob_b_asin_title

This is the gap I sealed and what I used

SilveradoRST · November 22, 2020

6 hours ago, Jrodpic said:

Hard to tell from the picture but that strip doesn’t look waterproof. I could see water getting in from the slant as well. My next move was to try and get some stripping in on top of the window.

It's not. I pressed down on it and it was saturate with water. If it rains long enough, that thing will be saturated and useless. GM should have used rubber instead.

In my opinion, short of GM using a new plastic for the frame of the window, sealant across the top of the frame is the best bet.

When I took my spoiler off, I notice the sealant that the dealer put across was great on the corners but very thin and almost non-existent in the areas near the middle, where the sliding window is. I still had water leaking on the driver side corner. I sealed the middle of the rear window on the outside with Kent sealant and now my corner leak has stopped. Not only is the plastic frame fragile and cracks, but the adhesive they used to adhere to the glass is also bad quality. Water was travelling from the middle of the top of the rear window, along the inside of the frame and finally leaking to the corner of the driver side inside. So the leak is not necessarily right above where the water is dripping from. It travels along the glass and the frame because of the poor adhesive.

No leaks for now. YMMV.

Edited November 23, 2020 by SilveradoRST

polarys425 · November 23, 2020

14 hours ago, SilveradoRST said:

There is some sort of spongy strip along that gap. It is adhere underneath the spoiler itself and sits in front of the body seam when the spoiler is on.

When I water tested my leak, I notice water would flow over the top of the spoiler and then drip along the slant that slants back towards the rear window. They end up on top of the rear window itself. Weather stripping the gap would definitely stop a lot of the water, but it won't stop those drips sliding along the slant especially in a long rain. Just my observation.

I'd say that spongy strip explains why long soaking rains are when most people notice leaks.

ShotgunZ71 · November 23, 2020

On 11/20/2020 at 7:38 PM, SilveradoRST said:

Bummer. I just sealed mine in a few areas the tech missed the first time around. Let's us know what you find when you get your spoiler off again.

Same here. We had a downpour recently and I found 2 smaller leaks this time. Much better than before, but I wanted to try again. Yesterday, I added more sealant to a few places and we will see if it helps. I'd just as soon do it myself until GM finds a true solution for it, or deal with it until I trade it.

Dali555 · November 23, 2020

19 hours ago, Jrodpic said:

This is the gap I sealed and what I used

Yep, that's the stuff I just requested a sample box of from the company itself. If after GMC "puts in a new window" it leaks again I'm going to put some just above the window in the gap between it and the wing.

Transient · November 24, 2020

I want to update and say mine is still not leaking, but I'm afraid I'll jinx myself.

So I will not say anything.

That's why I haven't posted in this thread for awhile. Crew cab trail boss

Sent from my SM-N960U using Tapatalk

Jac365 · November 24, 2020

5 hours ago, Transient said:

That's why I haven't posted in this thread for awhile. Crew cab trail boss

Sent from my SM-N960U using Tapatalk

Smart move. I asked if double cabs were having the issue also. The very next time it rained.......I find a leak! This after a whole year of no leaking issue. Already had taken back to dealership. Rear window removed and resealed. And it leaked again. To be continued....

ShotgunZ71 · November 24, 2020

When I noticed mine leaking again, I took the headliner down and poured water over the spoiler to see where it was coming from. There was no intrusion from any bolt holes, wire grommet, alignment pins, etc during that test. However, water was still coming in. From where, you ask? The dang, cheap-a$$, cracked window frame. Again! These window frames are developing hairline cracks that keep allowing the water intrusion. I sealed it up again to see if that helps. Time (and rain) will tell.

Are the solid windows leaking as well? Unless something has drastically changed with the design and production, all the sliding windows will leak. Whether the owner notices or not, they will leak at some point. It's sad to think someone buying a 2021 GM full-size truck will still have a crappy sliding window design. I'm sorry, the rest of the truck being trouble-free does not balance out the leaking rear window issues.

OnTheReel · November 25, 2020

Yup. And no, solid windows don’t leak, and neither do the spoilers on solid window trucks, oddly enough. Almost like it’s never the spoiler even when the dealer says it is.

Haven’t looked too hard at the solid window but I doubt it even has a frame. There would be no reason to have one.

I will maintain that there needs to be a bigger change than just the window frame or they would have done it by now.

Grey3liter4x4 · November 25, 2020

I had the dealer apply sealant per the TSB to my 2020 leaker. So far so good but from the sound of it it will most likely leak again as a crack develops in the window frame.

If it leaks again I'm going to apply https://www.grainger.com/product/3M-Black-Marine-Adhesive-Sealant-4YDL2?opr=APPD&analytics=altItems_2JBH1.

I used to do boat repair and 3M 5200 is about as bullet proof as you can get for an adhesive sealant. If applied properly it will be almost impossible for the window to leak. We used to attach boat cabs to hulls with this stuff. The only problem is it's basically permanent.

Jac365 · November 26, 2020

Has anyone with the rear slider been leak free?? Has anyone who had a leaker had a successful repair?

OnTheReel · November 26, 2020

49 minutes ago, Grey3liter4x4 said:

I had the dealer apply sealant per the TSB to my 2020 leaker. So far so good but from the sound of it it will most likely leak again as a crack develops in the window frame.

If it leaks again I'm going to apply https://www.grainger.com/product/3M-Black-Marine-Adhesive-Sealant-4YDL2?opr=APPD&analytics=altItems_2JBH1.

I used to do boat repair and 3M 5200 is about as bullet proof as you can get for an adhesive sealant. If applied properly it will be almost impossible for the window to leak. We used to attach boat cabs to hulls with this stuff. The only problem is it's basically permanent.

I was gonna say, god forbid you would ever have replace the window after using that stuff. It takes the gelcoat and fiberglass with it when you finally break it free on boats. 4200 might be a better option.

The seam sealer they use per the TSB is actually a fairly stout product. Think the main issue is the person applying it. A janky, broken substrate doesn’t help either.

ShotgunZ71 · November 26, 2020

1 hour ago, OnTheReel said:

I was gonna say, god forbid you would ever have replace the window after using that stuff. It takes the gelcoat and fiberglass with it when you finally break it free on boats. 4200 might be a better option.

The seam sealer they use per the TSB is actually a fairly stout product. Think the main issue is the person applying it. A janky, broken substrate doesn’t help either.

I used the 3M Flexiclear Body Seam Sealer on mine. The first round helped, we’ll see if the 2nd stops the leaks completely, at least for a while. May take it off if it doesn’t help and try the 4200 or 5200 mentioned.

Comscan · November 26, 2020

2 hours ago, Jac365 said:

Has anyone with the rear slider been leak free?? Has anyone who had a leaker had a successful repair?

I had mine done in August last year and i said at the time i believe it's mainly down to the quality of work done by the tech applying it, since then it has been in both gentle and torrential rain numerous high pressure wand and touchless washes and so far has been good no issues.

Ranger522vx · November 26, 2020

Has anyone actually had their slider replaced with a solid rear window? I was quoted $630 from a glass company to have it replaced and was told it would be able to be swapped. Just looking for any advice before I decide to go ahead and do it. I haven’t had the dealership try and fix it because from what I’ve heard there is no permanent fix and I don’t want to risk the damage when they try the repairs. What do y’all recommend?