High Mount Brake Light - Where does the water go?

[slovcan]

Hi folks,

I am sure my 1997 K2500 Extended Cab high mount brake light seal is leaking. It must be since it is 24 years old and looks pretty cracked up. Add to that the white water line stains in the headliner from the back to halfway along over the driver's door and around the passenger side overhead grab handle. A couple of weeks ago I saw the white water line stain on the headliner in front of the passenger side sun visor. About the same time I saw a bit of pooled water on the passenger side rubber floor mat.

So far all that stuff seems to be down to snow and ice standing on the roof for a week while it slowly melted away.

TODAY, however, I saw something new - water running down in front of my eyes from the top of the windshield onto the top of the steering column cover. It was actually a sustained fast dripping almost enough to call flowing as if a kitchen tap was turned on to a dribble. It did that a couple or three times for a second or so each time. I had just driven through a moderate rain and stopped at a red light when it happened.

I HATE leaks. What do you all think? High mount brake light seal? Maybe that plus the windshield suddenly starting to leak across the top? The windshield was replaced 5 years ago, but I am not so confident about that job - especially since the windshield they put in must have been Chinese since it seems to have been pre-sandblasted. Cracked now so due for replacement, anyway.

I have some closed cell weather stripping tape to make a new High Mount Brake Light gasket with - when it stops raining.

Thanks,
Glenn

 

[geeeee89]

I filled the crack between the windshield and the roof with clear silicone. Tape it off so once you squirt it in there you can mash it down with your finger and spread it without it getting on the paint. I got drips on the cab during hard rains or the car wash before that

 

[slovcan]

I filled the crack between the windshield and the roof with clear silicone. Tape it off so once you squirt it in there you can mash it down with your finger and spread it without it getting on the paint. I got drips on the cab during hard rains or the car wash before that

Thanks for that. I can see that being a solution for the "new" leak that seems to be from the top of the windshield. Sounds like the adhesive/sealant that holds it in (mine and yours) may have failed. We'll see what happens with a new windshield. By that time I should have the new brake light gasket done.

 

[slovcan]

Thanks for that. I can see that being a solution for the "new" leak that seems to be from the top of the windshield. Sounds like the adhesive/sealant that holds it in (mine and yours) may have failed. We'll see what happens with a new windshield. By that time I should have the new brake light gasket done.

Ok then, Sunday, sunny and pretty warm at 3C, I addressed the high mount brake light gasket and the windshield. Saturday was too cold and rained overnight and Sunday night/Monday morning had heavy rain forecast. When I opened the door Sunday morning the driver's side rubber winter floor mat was full of water. I had left a plastic bag draped over the steering column to help keep the water from getting into the electrics via the steering column(IF it leaked a lot). Well, it leaked enough that the plastic bag was also on the floor. The headliner was soaked along the front on both sides, but oddly not the foot or so length in front of the mirror.

I have a product called Lexel which is similar to silicone sealant, but less particular about temperature and wetness (supposed to be able to apply in cold wet conditions). I had the tip cut for approx 1/8" bead or a bit less. I squeezed that deep into the gap all across the top of the windshield. Then I left the heat on cremate while I went to work on the high mount brake light gasket.

After removing the light to get the original gasket out to use for a template, I noticed everything was perfectly dry underneath - no sign of recent dampness at all. I could see one stain like a water trace on the back of the gasket, but that was dry. While the gasket looked dry, ugly and porous on the outside edges, the sealing surface was completely smooth and undamaged. I cleaned up 24 years of crud that marked the roof where the edge of the gasket was, put a thin skim line of Lexel on the sealing surface of the gasket on put it back together. I guess I will have to readdress the roof seams where it joins the side panels. I was SURE I had the driver's side seams well sealed last year, but now I see I must have failed.

Sunny and warm forecast for today and tomorrow so I'll leave the windows open and hopefully get the headliner dry enough for a new rain test on Thursday.

Cheers,
Glenn