annoying drip from top of windshield

boybach

boybach

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Dec 9, 2020
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I have an extremely annoying couple of drips into the cockpit from the top of the windshield area. At first we thought was coming from the overhead running lights. It doesn't look like that's the source though, as the bases and the lenses have since been generously giped with polyurethane.

I'm thinking there could be a problem with the windshield seal - anyone have any experience with this type of leak? When things warm up and the rains ease, I'm planning to take a look at the seal between the roof and the windshield rubber, I think that MUST be where the water is getting in.

I've placed a receptacle to catch the odd drip, (it really isn't very much water - over a rainy week or so, maybe 2 tablespoons), but it's still a nuisance. To keep the humidity down I'm using a pillowcase half-filled with calcium carbonate sitting in a plastic tub in the cab with another on the kitchen counter. Interior has remained condensation free, but I really want to fix this damn leak!

Larry
 
Larry, if it's dripping near the steering wheel or cockpit seat then it could very well be the gap between the windshield gasket and front body cap. It's a known issue that Jim Bounds has posted about. There is a void in the body from the manufacturing process of the front cap mold that was filled with sealant and over time leaks. The void if I recall is close to the rear view mirror but the watwr can travel left or right. Sealing between the gasket and body works.
I had this and Sealing it worked. But you do want to be sure it's not the roof to cap seam, and marker lights as well.

HTH
Dave
 
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dservati said:
Larry, if it's dripping near the steering wheel or cockpit seat then it could very well be the gap between the windshield gasket and front body cap. It's a known issue that Jim Bounds has posted about. There is a void in the body from the manufacturing process of the front cap mold that was filled with sealant and over time leaks. The void if I recall is close to the rear view mirror but the watwr can travel left or right. Sealing between the gasket and body works.
I had this and Sealing it worked. But you do want to be sure it's not the roof to cap seam, and marker lights as well.

HTH
Dave
Click to expand...

Dave, it is dripping near the steering wheel, and I recall Jim Bounds talking about it in passing but not in a specific video I could find. It's good to hear that there is a gap there, I can deal with that! It must be similarly factory -filled like the two gaping voids at the back of the rail cap which over time destroyed all the cabinetry in the rear cabin/bed and the floor of the battery compartment. I rebuilt the cabinets etc and attended to those leaks and any others last summer - I was amazed how large a void was back there at the end caps!
After sealing all possible water entry points and seams with sikaflex and eternabond tape last year, I was disappointed to see those damn drips just as we were doing the final winterizing in November.
Thanks for the tip, I'll get it sealed up as soon as the weather breaks.

cheers

Larry
 
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So I've been going through a bunch of Jim Bound's videos this morning and I can't find the one where he talks about the leak dripping onto the steering wheel - anyone know which one that is?

Larry
 
boybach said:
Thanks Dave, got it. I'll be peeling back that gasket and filling it up with polyurethane!

cheers

Larry
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Be careful about "peeling back" the gasket. The approach I took was filling the void between the gasket and the roof/cap. I used 3M windshield buytle tape and pushed it in with my fingers then "smoothed" it out. I'm sure they sell it at tube but no one I had was left over from putting the windshield in my kid's Fiero.
 
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dservati said:
Be careful about "peeling back" the gasket. The approach I took was filling the void between the gasket and the roof/cap. I used 3M windshield buytle tape and pushed it in with my fingers then "smoothed" it out. I'm sure they sell it at tube but no one I had was left over from putting the windshield in my kid's Fiero.
Click to expand...
Fair enough. I'll have a good look at it when it warms up. I sealed the rear window by peeling back the gasket; it worked ok and I got it buttoned up well. I kept it open by adding toothpicks every few inches ...filled up the seam then pulled out the toothpick "wedges" as I went along. Cleaned up with methyl hydrate. :)
back window.webp
 
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Mine does the same. When parked I put a plastic trash bag over the steering wheel. If water drips on the horn button every thing in the column will rust, causing problems.
 
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Doug Smith made an excellant video of a windshield installation at GMCMI rallys. Kim Weeks has it and as soon it is available on line look at it. You can see how the new windshield installation is done and sealing of the gasket to the body is done. It is easy once you see the video. The leak over the steering wheel is a common problem on GMCs and solved there. There in one section on how they seal the top and the sides of the gasket to the body. It is not difficult.
 
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Well I hope Doug Smith get the video online soon!

I took a look yesterday and it's pretty hard to tell how it all goes together. I have a fiberglass eyebrow fitted plus the coach has been vinyl wrapped making it very difficult to assess what's going on at the seam. It looks like there isn't room to put any sealant in up there ATM - I think maybe a PO has used some sealant/caulk that I might have to remove along with a strip of the body wrap to see what's what.
 
Larry,
Kim has the video and will get it up soon.
The installers who did my windshield removed a run of old silicone at the top and side between the rubber windshield gasket and the fiberglass bodywork. After they installed a new windshield and bedded it in urethane they masked both the rubber gasket and body and ran a new run of silicone between the rubber gasket and bodywork at the top and sides. They used silicone again because it's the only thing that will stick to itself. If nothing had ever been used they would have left it alone or, more likely, used a run of urethane up there as well. Most people have direct experience with one or two GMC's so there are a lot of opinions based on anecdotal evidence. These people have done a LOT of GMC windshields and are more likely to put a run of urethane at the top and sides than not, unless they have to use silicone like on my coach. Unfortunately silicone does not retain the flexibility of urethane over time and a crack/separation on a coach like mine is more likely. I've been lucky with no leaks so far; I hope that holds. If you have a vinyl wrap you may well have to remove a strip to inspect it. Just remember that if silicone has been used before, it should be used again. The chemicals that will remove the silicone will take the paint as well and then you're really in the weeds.
Just my opinion.
Doug
 
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Thanks Doug, appreciate the advice. I had a look up there and couldn't actually determine how things were constructed. I do plan on removing a strip of wrap and whatever gipe has been used by the PO as an attempt to seal the area. Having a firm idea of the actual cross-section I'm dealing with will indeed be a big help!

I just wish I'd noticed a leak (this was the first winter with the coach) before I installed the eyebrow ..that isn't easily removable as I installed it with 3M 5200 last summer.

If I can't manage to seal the area after doing everything possible and recommended, my fall-back plan is to cut a narrow strip of Eternabond tape and cover the seam with that. Let's hope that won't be necessary.

thanks again for the advice, looking forward to the video!

Larry
 
Well it was educational watching the video, but more specifically MY education was in seeing the individual components and what was what.
Armed with that knowledge, I set about cutting away the old seal at the sides and top of the screen. The cavity between the frame gasket and the body and after removing the old sealant left a 3/8" square channel gap. I managed to get it reasonably clean but as I've mentioned before, the fiberglass eyebrow made the job much more difficult - I had to hold a flashlight in one hand and a removal tool or two with the other. Bit of a PIA, but I got it cleaned out eventually.

My plan was to reseal with polyurethane caulk, so first went in with a light application of the heat gun than followed that up by priming the channel with polyurethane solvent (methyl hydrate). I didn't use much, just a light brushing all along. I waited a little bit and made a cup of tea hoping that would be enough time to let it dry out before it rained as rain clouds were looking pretty ominous.
Anyway, masked it all off and filled the channel with polyurethane. Smoothed it out using the old wet-finger method, pulled off the masking tape and called it a day. It took an entire tube to fill that seam.

The rain started about an hour later -just a bit of spitting, nothing much, but by morning the next day it had rained and i just hoped there'd been enough time for it to skin over a bit before the rain really got going. Added to my concern was that this was done in early March with temps still not in the t-shirt and shorts range, far from it in fact!

I came back and checked on the work a few days later and to my disappointment, the yogurt container I'd put in place during the winter had about a tablespoon of water in it. It wasn't like the other times I'd seen clear water in that container - the water this time was sort of yellow-brown. So, bit of a fail. There wasn't much water but some is a LEAK, and that's no good. I figured I'd have to do it again when the weather warmed up and left it at that.

Went back today, which would be about a week or so since last time and even though it's been raining hard for quite a few days, the container was bone dry. I think I must have fixed it - I think the yellow water I saw last time was just the remnants of trapped water finally draining out. As no more came in, I really do think the recaulking has fixed it.

Larry
 
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Good work Larry.
I hope it is truly fixed. Regarding the water in the cup, I always thought that when clean water was caught it was not very informative, but if the water has color or sediment then that suggests it has traveled some, picking up smutz. An example might be the front clearance lights. A water leak there might pick up some of the accumulated grime on top of the cockpit headliner on its way to the windshield. Just a thought.

You might consider changing your sig file to lose "ol' leaky"
Doug
 
dsmithy said:
Good work Larry.
I hope it is truly fixed. Regarding the water in the cup, I always thought that when clean water was caught it was not very informative, but if the water has color or sediment then that suggests it has traveled some, picking up smutz. An example might be the front clearance lights. A water leak there might pick up some of the accumulated grime on top of the cockpit headliner on its way to the windshield. Just a thought.

You might consider changing your sig file to lose "ol' leaky"
Doug
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Doug, compared to the unbelievable number of leaks this coach had before I attended to them, this windshield leak was really just a drop in a bucket. :) The ol'leaky sigfile is there precisely because she DOESN'T leak anymore, kind of my idea of a warped joke.

When I got the coach, one year ago this week, boy did she leak.

The entire rear bedroom/salon chipboard woodwork had doubled in size and turned to powder due to leaks at the rail ends -and of course- the fact that the idiot that did the vinyl wrap wrapped over all the window drains, causing water to cascade down the walls in the main salon and everywhere else. Rainwater accumulated in the window frames and unable to escape through the covered-up drains, overflowed, resulting in the swelling and disintegrating the lower wall material. Even the floor of the battery box had rotted out due to the continuous leak from the rail caps.

After cutting away the wrap from the windows the majority of the leaks stopped. I renewed the walls, built new cabinetry in the aft bedroom, fixed the rail ends, eternabonded all the roof seams and rebuilt the salon walls.

I still have the roof seal gasket at the A/C unit to replace, but I'm waiting for the better weather to do that job.

Hopefully she'll be all buttoned up after that.

Larry
 
I have a leak that comes out of the headliner and drips on my leg/seat. Depends on the angle of the coach. I removed the headliner and found the leak to be under the cap at the end of the drip rail. I am in the process of resealing the roof seam and the drip rail.
 
GlenC said:
I have a leak that comes out of the headliner and drips on my leg/seat. Depends on the angle of the coach. I removed the headliner and found the leak to be under the cap at the end of the drip rail. I am in the process of resealing the roof seam and the drip rail.
Click to expand...
Good idea. My drip in that location was from the windshield seal and touch wood it's still fixed.
 
Applied GMC

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