Rear Window Leak (with fix)

[UltimateToolReviews]

Yeah, so just like my other 4 rams and Tacoma, another truck gets the rear window leak. Seems no brand is safe. Ram and GM are both using these garbage plastic rear window frames that crack super easy. Took about 2 hours to figure out how to remove the rear headliner, back spoiler and light assembly and clean the glass channel and seal it up good. Both GM and Ram want to just replace the entire rear back glass, but it will just crack again and leak again. Super annoying, but if you fix any truck with the rear window leak, you can fix any of them. 2 hours and $17 will fix it for good. Don't pay the dealer thousands to band aid it.

 

One tip, once you apply a few beads of silicone, run a paper towel and create a trough like dip in the channel, than apply one more bead and use a blower to push the sealant in more. It helps really seal up any cracks and also if new cracks appear, they can't leak.



I used this video and sealant to fix it (not my video, found on reddit)

video I found

window sealant used Need at least 2x

[EXSlider400]

https://www.gm-trucks.com/forums/topic/255000-diy-sliding-window-leak-permanent-repair/#google_vignette

 

I did the repair above to a 2019 1500 and it lasted, but just got a 2025 2500… is this still an issue with the new trucks…I assume yes.  
 

 

Edited June 23, 2025 by EXSlider400

[Pryme]

I’m glad my rear window doesn’t have a slider and no roof lights to leak. I’ve had rear sliders and never used them anyway. 

[UltimateToolReviews]

10 hours ago, EXSlider400 said:

https://www.gm-trucks.com/forums/topic/255000-diy-sliding-window-leak-permanent-repair/#google_vignette

 

I did the repair above to a 2019 1500 and it lasted, but just got a 2025 2500… is this still an issue with the new trucks…I assume yes.  
 

 

Don't know about the 25s, but if you have a back slider with a plastic frame, it will crack and leak. Not if, but when.

[carkhz316]

Silicone is junk for the exterior of your vehicle, regardless if its indicated to be for glass/ windshields. It'll eventually haze and start drying up. The better choice is urethane which is what is actually used for gluing glass in. You can get a tube large enough to glue the whole back glass for $20.

[UltimateToolReviews]

9 hours ago, carkhz316 said:

Silicone is junk for the exterior of your vehicle, regardless if its indicated to be for glass/ windshields. It'll eventually haze and start drying up. The better choice is urethane which is what is actually used for gluing glass in. You can get a tube large enough to glue the whole back glass for $20.

Urethane won't flow into the cracks were the water is getting in, if Urethane worked we wouldn't need to be fixing the back windows since that's what's already on there. You need silicone because it has some flex to it and wont crack. 

[Pryme]

Good silicone will last 15-20 years easy. Seems these trucks are sold off after 1-2 years. Flowable silicone is best for fixing water intrusion issues. It is after all what aquarium manufacturers use. 

[carkhz316]

On 6/24/2025 at 4:09 PM, UltimateToolReviews said:

Urethane won't flow into the cracks were the water is getting in, if Urethane worked we wouldn't need to be fixing the back windows since that's what's already on there. You need silicone because it has some flex to it and wont crack. 

The rear window leak is not because of the bead of urethane thats used to install the glass. Its the plastic frame that cracks and leaks. Water then wicks along the inner channel of the sliding glass frame, and seeps in around the corner to the interior side. Thats why you see water dripping in the same spot of most of the trucks in the upper outboard corner of the window frame where the track ends.

 

 

Quote

Good silicone will last 15-20 years easy. Seems these trucks are sold off after 1-2 years. Flowable silicone is best for fixing water intrusion issues. It is after all what aquarium manufacturers use. 

It won't. The reason why the "fix" is silicone is because its the cheapest solution, which is always the case for warranties and the like. Its always that way otherwise the OEMs would fix it the right way and replace the glass; hence why many report repeated failures of the sealant, only for GM to cave and replace the glass anyway. Further, aquariums are not a car and they don't sit outside in the elements.

Edited June 29, 2025 by carkhz316