annoying drip from top of windshield

[74_Coach]

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

It’s finally raining out here in CA and like clockwork the windshield gasket is leaking. It’s about an inch from the rear view mirror bracket and the gasket has a bump in it with water dripping over it (expand image). Because my MH is parked in the driveway at about a 2% grade uphill and leaning slightly to the passenger side, the water is also leaking over the passenger seat area where your legs would reside.

Ed

 

[boybach]

It’s finally raining out here in CA and like clockwork the windshield gasket is leaking. It’s about an inch from the rear view mirror bracket and the gasket has a bump in it with water dripping over it (expand image). Because my MH is parked in the driveway at about a 2% grade uphill and leaning slightly to the passenger side, the water is also leaking over the passenger seat area where your legs would reside.

Ed

Ed, Just reef out the sealant between the windshield gasket and the body cap and fill the seam with a tubefull of polyurethane caulk (see my earlier post).

My coach is bone dry so far this winter after doing that repair last March. Touching wood as I type BTW!

Larry

 

[Ken B]

If there is already sealant between the gasket and the body, then someone has already tried in the past to seal it. GM installed them without sealant. Clean out any sealant there and replace all of the sealant all the way across the top (and maybe down the sides) too with one long bead. One big problem doing this is if the original sealant used was silicone. Urethane will not stick long term and you need to replace the sealant with silicone. If it is clean up there then use urethane. There is a cleaner you can use to remove the old silicone residue but it damages the paint. So do not use it.

Doug Smith made a great video tape that is posted on the GMCMI web site on how this all done.

GMC Motorhome Technical Handouts

Guidelines, installations, papers from presentations for the GMC Motorhome.

www.gmcmi.com

Page down The presentation is the one labeled "Windshield replacement Clinic" Starting around 15:35 is where they seal the top of the windshield to the body.

 

[74_Coach]

If there is already sealant between the gasket and the body, then someone has already tried in the past to seal it. GM installed them without sealant. Clean out any sealant there and replace all of the sealant all the way across the top (and maybe down the sides) too with one long bead. One big problem doing this is if the original sealant used was silicone. Urethane will not stick long term and you need to replace the sealant with silicone. If it is clean up there then use urethane. There is a cleaner you can use to remove the old silicone residue but it damages the paint. So do not use it.

Doug Smith made a great video tape that is posted on the GMCMI web site on how this all done.

GMC Motorhome Technical Handouts

Guidelines, installations, papers from presentations for the GMC Motorhome.

www.gmcmi.com

Page down The presentation is the one labeled "Windshield replacement Clinic" Starting around 15:35 is where they seal the top of the windshield to the body.

Thanks. I did watch that video including the Jim Bounds video but I need to find a glass shop that will work on RV’s. The windshield gasket does need to be replaced (which I now have) and both windshield glass have already been replaced but the glass shop I used no longer does RV’s.

 

[RJW]

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

cheers

Larry

If there is already sealant between the gasket and the body, then someone has already tried in the past to seal it. GM installed them without sealant. Clean out any sealant there and replace all of the sealant all the way across the top (and maybe down the sides) too with one long bead. One big problem doing this is if the original sealant used was silicone. Urethane will not stick long term and you need to replace the sealant with silicone. If it is clean up there then use urethane. There is a cleaner you can use to remove the old silicone residue but it damages the paint. So do not use it.

Doug Smith made a great video tape that is posted on the GMCMI web site on how this all done.

GMC Motorhome Technical Handouts

Guidelines, installations, papers from presentations for the GMC Motorhome.

www.gmcmi.com

Page down The presentation is the one labeled "Windshield replacement Clinic" Starting around 15:35 is where they seal the top of the windshield to the body.

I too had that leak by the rear view mirror. It was so bad that I used to put pails under the mirror when ever it would rain to catch the water.

I had them do my windshields back in 2012 and was disappointed that I still had the leak. After watching the windshield video a few minutes ago I can say that they did not do the step shown at about 16:40 on mine. I know that because this past fall I cleaned out all the old sealant above the windshield rubber. I know the old sealant was there before the new windshields were installed. I taped it as shown in the video and used 3M window-weld 08609 to seal the gap. Now for the first time in a very long time it doesn't leak. That step, if they had done it, would have saved me a lot of grief over the past 10 years.

 

[boybach]

Urethane will not stick long term and you need to replace the sealant with silicone.

I'm guessing you mean that urethane will not stick to silicone, right? Indeed it won't. That's why you remove all traces of it before filling up with urethane.

Silicone has nothing like the adhesive ability of urethane and I would never choose silicone over urethane anywhere where I needed a long term caulk. Of course beginning with a clean surface is also necessary if you want a success experience.

I use marine technology whenever I deal with leaks and you won't find silicone used anywhere on my boat!

Larry

 

[RJW]

I don't believe what I removed was silicon.

If mine leaks again, at least I will know where to look.

 

[Ken B]

It is not the old silicone not being removed that causes the problem. It is an oil like substance that leaches out of the silicone over time and stays on the surface of or in the paint. Once that oil like substance is there the urethane will loosen up over time.

They make a special cleaner that painters use to some how dissolve or remove the oil before repainting a vehicle. It is OK in their case to use it because they are not worried about dulling or removing some of the paint. Back in the 1960's several companies introduced silicone added car wax. Body shops hated it when doing repairs that included painting existing panels. I do not think any company makes silicone added car wax any more.

I do not like using silicone, but in this case I make an exception after mine loosened up after 2.5 years. The guys that do ours at the rallies have done well over 150 GMC windshields over the years. Only 2 they have done have come back for the problem. Both were installed with urethane. Mine was one of them. They removed the urethane and sealed it again with silicone about 16 years ago. I have had no problem since. They also have fixed several others that were installed by other shops. GM and most shops do not seal up there at all.

It you do have the urethane loosening problem after a couple of years, it is an easy hour or two job to remove the urethane (it pulls right out all the way around) and then replace it with silicone.

One last comment. Silicone based windshield treatment can also cause this problem as some of it migrates up there if you drive in the rain. This not as big of a problem as the direct application of silicone there as a sealant.

 

[Ken B]

I'm guessing you mean that urethane will not stick to silicone, right? Indeed it won't. That's why you remove all traces of it before filling up with urethane.

Silicone has nothing like the adhesive ability of urethane and I would never choose silicone over urethane anywhere where I needed a long term caulk. Of course beginning with a clean surface is also necessary if you want a success experience.

I use marine technology whenever I deal with leaks and you won't find silicone used anywhere on my boat!

Larry

I'm guessing you mean that urethane will not stick to silicone, right? Indeed it won't. That's why you remove all traces of it before filling up with urethane.

Silicone has nothing like the adhesive ability of urethane and I would never choose silicone over urethane anywhere where I needed a long term caulk. Of course beginning with a clean surface is also necessary if you want a success experience.

I use marine technology whenever I deal with leaks and you won't find silicone used anywhere on my boat!

Larry

Larry,
I do not disagree with you but please read my previous posting I just made in this thread. The problem is how to get it surgically clean once someone has used silicone previously.

 

[74_Coach]

I believe I found another glass shop that works on RV’s. Since I am having both windshields removed and a new gasket from Coach Glass installed, do I need the polymeric sealant applied to the window frame then install the gasket or install the gasket dry on the window frame then squeeze the sealant in after installing the windshield. Jim Bounds video didn’t specify a sequence and I don’t want to repeat this installation because of new leaks.

 

[Ken B]

Yes Yes Yes

It only adds about 15 minutes to the job and uses one or two tubes of sealant. The leak over the top has been a problem since day one on these coaches A new gasket probably will not fix your leak problem.

Also have them seal the edges of the glass with the liquid that looks like black fingernail polish. After inserting glass and before installing the locking bead/ring, On the outside of the windshield go around under the seal along the glass and insert urethane . This is all to prevent the glass from getting air and water in there and fogging the windshields over time. You will not be happy 8 or 10 years from now with windshields that are fogging around the edges again. These three things are easy to do now. Not so easy later. Watch Doug's windshield video and see what I am talking about on sealing .

If you are still looking for an installation company locally, look for a company that does truck and bus windshields. They should have the experience in doing what you need. That is what the three three guys in the video do daily for a living. You will notice they do not talk much as they know what to do working together and they just go get it done.

A word of warning on that gasket. Replacing it requires BOTH windows be removed at the same time. The glass is part of the body of the coach. Coach Glass requires that the upper roof area be supported while removing the second glass and center support. The support must stay there until reinstalling the center support and the first new glass.

Take a picture of the support in place with both windshields removed and keep it in case you have a future warranty claim. .

I use to have a document from them on this. I will see if I can find it. They did not remove both windshields at the same time in the Doug's video. They will only do that in their shop.

 

[Ken B]

I just re-read your posting and realize that I did not answer your question. I have never seen them replace a gasket because it is rarely done and only done in their shop. I will call the owner and ask him tommorrow. I think I know the answer but I would rather ask the expert first before posting.

 

[74_Coach]

I just re-read your posting and realize that I did nince ot answer your question. I have never seen them replace a gasket because it is rarely done and only done in their shop. I will call the owner and ask him tommorrow. I think I know the answer but I would rather ask the expert first before posting.

Thanks for your detailed post. I wonder if Coach Glass does installs.

The only reason for replacing the gasket is because it’s shrinking at the bottom sides and front of the windshield causing leaks inside at the firewall - passenger side is the worst.

 

[LarryW]

This is probably a good time to tell people that If you are going to remove the windshields, when the windshields are out, take the time to remove all of screws holding the dash to the body that reside up at the windshield. They are Philips screws. Remove them, and replace with a SS screw of the same size and place a little white lube on the threads. Then tighten them snug only. Some day if you need to take those screws out, when the windshields are in, backing the screws out at the windshield angle, they will come out quite easy. In addition, while the windshields are out, take the time to clean up the windshield edges and apply some kind of sealer to the edges. Over time, moisture can seep between the gasket and the glass, working its way between the layers of the safety glass creating the fogging effect that we see on older installations. Sealing the edges will delay or prevent this fogging from happening. JWID

 

[tmsnyder]

Yes Yes Yes

It only adds about 15 minutes to the job and uses one or two tubes of sealant. The leak over the top has been a problem since day one on these coaches A new gasket probably will not fix your leak problem.

Also have them seal the edges of the glass with the liquid that looks like black fingernail polish. After inserting glass and before installing the locking bead/ring, On the outside of the windshield go around under the seal along the glass and insert urethane . This is all to prevent the glass from getting air and water in there and fogging the windshields over time. You will not be happy 8 or 10 years from now with windshields that are fogging around the edges again. These three things are easy to do now. Not so easy later. Watch Doug's windshield video and see what I am talking about on sealing .

If you are still looking for an installation company locally, look for a company that does truck and bus windshields. They should have the experience in doing what you need. That is what the three three guys in the video do daily for a living. You will notice they do not talk much as they know what to do working together and they just go get it done.

A word of warning on that gasket. Replacing it requires BOTH windows be removed at the same time. The glass is part of the body of the coach. Coach Glass requires that the upper roof area be supported while removing the second glass and center support. The support must stay there until reinstalling the center support and the first new glass.

Take a picture of the support in place with both windshields removed and keep it in case you have a future warranty claim. .

I use to have a document from them on this. I will see if I can find it. They did not remove both windshields at the same time in the Doug's video. They will only do that in their shop.

Is all this done when glass is replaced at a GMCMI Rally? I'm planning to get new glass at the next rally that offers it, if I can make it there.

 

[LarryW]

Is all this done when glass is replaced at a GMCMI Rally? I'm planning to get new glass at the next rally that offers it, if I can make it there.

IIRC, they do seal the glass edges. I'd ask and if not, get to the glass and do it yourself. I don't think they will do the dash screws, so you may have to be there when the windshields come out and replace the screws yourself. If you don't have access to SS screws, remove them one at a time, using the old screws, coat the threads with whatever lube that you can get your hands on and replace them, snug only. JWIT

 

[Ken B]

Yes they do all of that except loosening the screws. I suggest that you get new stainless screws with the heads painted at your favorite hardware store and they will allow you to loosen or replace them while they take a quick break. That is the ideal time to remove and replace them.

As far as sealing them, If you watch Doug's video, these are the guys that do the work. Doug made the video at one of our rallys. I was not there. I had just got out of the hospital the previous week and was not up to getting the coach ready and driving that far. So Larry W filled in for me.

 

[Ken B]

Thanks for your detailed post. I wonder if Coach Glass does installs.

The only reason for replacing the gasket is because it’s shrinking at the bottom sides and front of the windshield causing leaks inside at the firewall - passenger side is the worst.

Coach Glass has a sub-company that does installs. It is RV Glass Solutions. I think this is their website: https://rvglassexperts.com/

I have never used them. They sign up independent installers all over the country, coordinate their orders, and stand by their work. It is a separate operation with a separate phone number.

I have been coordinating the GMC rally installs for more than 15 years and I have been very, very happy with Coach Glass. They jump through hoops to do anything I need for rallys. RV Glass solutions are probably the same way.

Call them.

If you are within 150 miles of Chicago, or coming through the area, Call me and I'll get the guys at Preferred Glass to to do the work.

When we do the next rally and I get things set up, I will open up a separate email for this called gmcwindshields. I will ANNOUNCE IT HERE usually 60 TO 90 DAYS BEFORE THE START OF THE RALLY. Kim Weeks will also announce it on GMCMI.

 

[74_Coach]

Coach Glass has a sub-company that does installs. It is RV Glass Solutions. I think this is their website: https://rvglassexperts.com/

I have never used them. They sign up independent installers all over the country, coordinate their orders, and stand by their work. It is a separate operation with a separate phone number.

I have been coordinating the GMC rally installs for more than 15 years and I have been very, very happy with Coach Glass. They jump through hoops to do anything I need for rallys. RV Glass solutions are probably the same way.

Call them.

If you are within 150 miles of Chicago, or coming through the area, Call me and I'll get the guys at Preferred Glass to to do the work.

When we do the next rally and I get things set up, I will open up a separate email for this called gmcwindshields. I will ANNOUNCE IT HERE usually 60 TO 90 DAYS BEFORE THE START OF THE RALLY. Kim Weeks will also announce it on GMCMI.

Wow, thanks again for your response! I bought my motorhome in 2019 and have replaced anything rubber, new fuel tanks, window weatherstrip and new windshields in 2021 but this leak has been so elusive - until now. I am considering removing the front inside cap to look for additional leaks but don’t want to crack it. I will call Coach Glass and find out about windshield installation.

I live on the CA Coast and still making this coach safe to drive so not heading to Chicago anytime soon. It goes in March 2023 to replace the cracked exhaust manifolds using Lenzi copper gaskets and replacing the entire exhaust system with stainless steel. I have the knowledge and experience to replace the manifolds myself but not a flat cement pad to work on it. I did attend my first Western States Rally in Pismo Beach October 20-23. The motorhome performed perfectly for that duration and I look forward to getting it on the road in 2023!

 

[Ken B]

I just re-read your posting and realize that I did not answer your question. I have never seen them replace a gasket because it is rarely done and only done in their shop. I will call the owner and ask him tommorrow. I think I know the answer but I would rather ask the expert first before posting.

I thought I replied to this but it sure is not showing up right now.

I talked to Paul owner of PDK (Preferred Glass). He said in 35 years and over 200+ GMCs he can remember doing three new gaskets when they replaced the windshields. I asked about sealing the gasket to the body when installing it prior to the windshields being installed. He said the way they seal the windshields to the coach body that the added sealant you are talking about is unnecessary. He would not do it. He said if you choose to do it, the only possible problem he sees is if they take too much time between installing the gasket and installing the glass and that time allowed the sealant to set up or even partially set up. Then there is a chance that the windshield could be broken during install or later while driving down the road. He said to only seal one side and immediately install the windshield. Then seal the gasket on the other side and immediately install the second one.

Again he said he would not do it. Just seal them like you see in the video and you should be OK.

Ken B.