Originally Posted by Mstr2u
Thank you for the excellent post and discussion! Unfortunately, I have yet to isolate the root cause of my leak. As you will see from the pictures, the sunroof area on my truck is leakproof and I have opened it after a good rain and checked all rail areas...all dry. The pictures will show where my leaks originate, and also where I suspect the intrusion is coming from. Also note that the drips occur after the vehicle has been sitting on a level surface after rather substantial rain (we get a bit of it here in Germany). Also note that this problem did not occur until approximately 12 months ago (even in the torrential rains of Florida).
Any help is appreciated!
The best method to find a leak is to take the headliner corner where the leak is coming from down, and keep it down (you can use zip ties to hold in place) and wait for the rain. I had no trouble with the headliner assembly, but other members have had a rough time re-attaching the sun visor support. There are many threads on that. I believe I posted some pics on that in at least one thread out there. You can use a water hose instead of waiting for the rain.
My truck is the poster child for water leaks. The leak path I show in post 1 of this thread was not the only leak path I found on my truck. I also had a leak from where you suspect yours is coming from - under the top corner of the driver's side of the windshield. Mine, however, happened shortly after I had the windshield replaced. This leak path will cause water to puddle under the A Pillar’s plastic trim piece. The back of the trim piece has ribs, and the water will collect on it. This leak on mine never made it to the carpet of the truck. The water was not much and it would stay on the A pillar trim piece ribs until it dried. This possible leak path however will not explain the water dripping from the tiny hole in the sunvisor support on your truck (your pic #4), since your leak happens while the truck is parked on level ground, and even the highest point on the wind shield is still lower than the visor support, and the headliner at the front edge curves down. Gravity would rule out your suspect leak path as the culprit. For my truck, I removed the molding on the side of the winsdshield – The one that goes up and down on one side of the truck, not the one that goes across from the driver to the passenger side. The vertical one is screwed on. If you carefully move the weatherstrip out of the way, you should see the screws. I ran silicone on the top corner of the windshield (between glass and sheet metal) and that leak path to the A Pillar was fixed. It’s easy to remove the A Pillar trim to check for water on the ribs. The piece is only held on with clips. You can start from the top side and carefully pull it away with your hand – don’t use a lot of force.
My next guess would be the roof rail screws, specially the front one or two on the side your visor mount is dripping. Remove the screw and see if the screws are rusted at the tip. There are 6 screws holding each rail down to the roof, and thanks to a ‘brilliant’ design direction approved by GM, the holes in the sheet metal for the screws go all the way through, or atleast they do on 2002MY. You can take a screw out and look right down at the headliner. Atleast two of my screws were rusted all the way through to the tip. In my case, they were the rear ones, and the rear end of my truck also leaked water. So, all of my 12 roof rail screws now have white plumping tape on them, a tiny dab of silicone on the threads over the plumping tape, and generous amounts of black silicone covering the entire exposed screw head areas.
Another leak I found - and this is the one I am yet to forgive GM for putting me through – I discovered after I thought my work on roof rail screws was enough and I still had a leak that appeared to be coming from the rail screw openings – the rear right one in my case. So, I took the rails off, used masking tape to cover the screw holes, had the rear half of the headliner hanging down, and waited for the rain – this was during a rainy season in Detroit, I only waited less than 24 hours for Mother Nature. I laid down in my truck in the rain with the headliner pulled down and gazed in awe and endless amusement as the drips came down roughly 10 seconds apart from the dimple caused by an aggressive spot weld between the quarter panel and roof sheet metals. I have to admit I laid there for about 10 minutes staring at the drips, as I pondered the whole chain of events that led me to purchase a GM product to begin with. It’s one thing for gummy seal to wear around a sunroof rail or even for an engineer to sign off on open ended screw holes on the roof, but how do you screw up a spot welds? How many years now have the auto industry been spot welding? So long story short, I used more silicone on the bad weld spot in the trough area under the roof rail. You can see what I mean in the two graphics attached.
Oh and I had another leak from around the third brake light – chimzel? Is that what they are called? So I have silicone around and in the top gap between the light and plastic trim piece it goes in.
All in all, I used about 5 oz. worth of silicone on this truck to cover up leak paths. But hey, not a drip for more than a year now, so at least this story had a happy ending.