I have factory cab lights.
Water intrusion
- Thread starter Cougar281
- Start date
So bringing this back up, I found another leak, both cab vent seals were dry rotted and cracked, allowing water in there. Teplaced them with Dorman replacements and still leaking 
. The Dorman seals don't seem to be 'squished' as much as they should.
But for this upper leak, I removed the visor and center console and ran a camera across to look at the marker and onstar antenna (it's raining now and the corner of the headliner is wet), and both the marker light hole and onstar hole appear to be bone dry. No sign of any moisture or drips.
Probably the only way to find it will be to remove the headliner, which of course is NOT an easy job...
Oh, and I did replace the center brake light assembly because it was all UV damaged and whatnot.
. The Dorman seals don't seem to be 'squished' as much as they should.But for this upper leak, I removed the visor and center console and ran a camera across to look at the marker and onstar antenna (it's raining now and the corner of the headliner is wet), and both the marker light hole and onstar hole appear to be bone dry. No sign of any moisture or drips.
Probably the only way to find it will be to remove the headliner, which of course is NOT an easy job...
Oh, and I did replace the center brake light assembly because it was all UV damaged and whatnot.
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GM still has the cab vents available. I replaced mine about a year ago and they are nice and sealed.
Since it's the same for every truck from 1999 to 2025, I'd hope they still have them! ??
At any rate, for whatever reason, the dormans POUR water in at the bottom. I'll have to try and post a video clip of it. I pulled the trim out, pulled the vents and the vent tube things then reinstalled the vents and ran water down the back of the truck and water POURED in at the bottom. Removed the Dorman and installed the OE one I got from a local dealer and nothing. Dry as can be. The OE and Dorman 'APPEAR' to be identical, so I don't know why the big difference. Maybe the Dorman plastic is a tad more flexible and not quite allowing the seal to seal right? ?
Dorman stuff is usually OE quality or better, but apparently not in this case for some reason.
So one big leak sealed up finally. Next fun project: removing the headliner to find the other one.
Edit: here's a clip of the water pouring in.
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Dorman Sucks!!!! I am SOOOO Tired of there Shitty replacement parts.
I don't recall if the New GM CHMSL comes with a seal or not. If it doesn't, you need to order one. There is a few aftermarket companies offering the foam seal. I recall having mine replaced when they painted the roof. The shop adjuster was surprised that I found it.
I believe I purchased mine from VIPMOTOZ on EBay. It's been more than 5 years since I purchased the so i forget. There are other sellers and I see them on Scamazon too.
I don't recall if the New GM CHMSL comes with a seal or not. If it doesn't, you need to order one. There is a few aftermarket companies offering the foam seal. I recall having mine replaced when they painted the roof. The shop adjuster was surprised that I found it.
I believe I purchased mine from VIPMOTOZ on EBay. It's been more than 5 years since I purchased the so i forget. There are other sellers and I see them on Scamazon too.
WaterProof Foam 3rd Brake Light Seal Gasket For 99-06 Chevy Silverado GMC Sierra | eBay
1999-2006 GMC Sierra 1500 | 2500 | 3500. 2007 GMC Sierra Classic 1500 | 2500 | 3500. DESIGNED TO FIT1999-2006 Chevrolet Silverado 1500 | 2500 | 3500. 2007 Chevrolet Silverado Classic 1500 | 2500 | 3500.
www.ebay.com
That's a bit of a broad brush...this is really the first dorman product that I've had an issue with... And in some cases, what they've created is far superior to the oe part... Take the oil filter/cooler assembly for the 3.6 pentastar... The oe part is all plastic. The dorman part is all metal. Now, the main failure mode is not the plastic cracking as far as I know, but the o rings and other rubber seals drying out, flattening and cracking, but as far as I know, there's no o rings kit and the solution is to replace the entire unit... I'd take dormans metal replacement over the oe plastic one for a similar price any day. The only way that could be made better is if dorman offered an oring kit for the pentastar oil filter/cooler assembly.Dorman Sucks!!!! I am SOOOO Tired of there Shitty replacement parts.
I don't recall if the New GM CHMSL comes with a seal or not. If it doesn't, you need to order one. There is a few aftermarket companies offering the foam seal. I recall having mine replaced when they painted the roof. The shop adjuster was surprised that I found it.
I believe I purchased mine from VIPMOTOZ on EBay. It's been more than 5 years since I purchased the so i forget. There are other sellers and I see them on Scamazon too.
WaterProof Foam 3rd Brake Light Seal Gasket For 99-06 Chevy Silverado GMC Sierra | eBay
1999-2006 GMC Sierra 1500 | 2500 | 3500. 2007 GMC Sierra Classic 1500 | 2500 | 3500. DESIGNED TO FIT1999-2006 Chevrolet Silverado 1500 | 2500 | 3500. 2007 Chevrolet Silverado Classic 1500 | 2500 | 3500.www.ebay.com
And the dorman CHMSL did come with all gaskets.
Weve had the dorman 3.6 oil cooler not seal right out of the box. Kept leaking at the o-ring. After pulling it a 3rd time, we found it was warped just enough. Fuck that bull shit… weve probably done 40-50 coolers in the last couple years. We tried the dorman ones and got to the 3rd one when this happened. All the factory ones never had that issue. Eventually the factory ones will leak but you can atleast get 50k miles out of them lol
Yeah Dorman sucks. Would never consider it OE quality or better lol
There are some things they do good at though, the problem solver shits or whatever they call them sometimes are actually decent
There are some things they do good at though, the problem solver shits or whatever they call them sometimes are actually decent
I just happen to have a Pentistar work van and it had to have that part replaced. Like James mentioned, even that part has it's quality issues as well...
Just had a call on Friday. The heater core fitting wouldn't come off on a Silverado.... Took my removal tool thinking the persons might not be long enough to release the tangs in side. never had an issue with a GM unit. Nope!!! It's a Dorman replacement part... had to cut it off, was replaced with Dmax store units so it could be serviced in the future if ever needed.
I have a 2012 2500HD that had a very similar issue. It caused the front floor to rust and the channel running to back seat.
I found the cab lights were leaking. The lights (including after market ones) are manufactured flat but the roof has a slight curve. I tried replacing them but could not get them to seal properly. The mounting design is horrible and does allow them to tighten properly. I figured out the only way to pull them down would be to use machine screws with a nut and a large washer inside the cab to tighten them down snug. I opted to eliminate them. My roof has Herculiner on it (due to rust several years ago) so I removed the lights and closed off the wire leads. I scraped the Herculiner off around the holes and cut patches out of sheet metal. I installed the patches over the holes using seam sealer under the patch and over the edges. After the seam sealer cured I rolled Herculiner over the patches and it blended in perfectly. No more leaks.