Sealant For Leaking Windshield

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Mar 17, 2011
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I have developed a leak on the top of the windshield on my 98 Expedition. I have removed the upper gasket trim piece to expose the glass and metal. I have removed the loose glass seal material, removed the loose rust that probably caused the problem to begin with and primed the bare metal and rust areas. with a rust converter. Now I need to re-seal the windshield (just the upper part). I think the gap is a bit big for flowable silicone.
Any ideas on a product I can use to re-seal the windshield gap? Something that is readily available at Home Depot or auto parts store would be best. I would like to finish this before the next rain.
 
I’d probably want to coat the rust in POR epoxy to get a solid surface, then use butyl tape. No idea how long it will last.
 
Flowable silicone is meant for this job, if you don't think that will do it, you probably just need to get the windshield replaced if you want to fix it.
 
Flowable silicone is meant for this job, if you don't think that will do it, you probably just need to get the windshield replaced if you want to fix it.
I think the flowable silicone would work for the majority, but there is about 3 feet of 1/4" to 3/8" gap to fill in the middle
 
You’re probably going to have to have it replaced. It’s put in with polyurethane caulk. Has this windshield ever been replaced in the past?
 
I was leaning towards something like the silicone bandaid. Perhaps using regular silicone for the thicker viscosity to fill the larger gaps, followed up with flowable silicone to get into the remaining voids.
Maybe black RTV Silicone?
 
Loctite E-20NS 1.69 oz. Cartridge part no. 6430A29 @ $17.29 each at McMaster-Carr

But you will need the reusable manual dispensing gun part no. 74695A71 @ $ 23.76

One of the mixing nozzels part no. 74695A12 @ $ 1.30 ( you can mix these epoxies on a piece of cardboard but you need the gun to dispense it so both tubes move the same amount. ) But the nozzel is nice to use for a job that uses a lot of the epoxy.

The NS stands for no sag and this dries to very good epoxy that will stick to glass and metal extremely well, and really does not sag when it is uncured. It can handle heat and cold. I had some and my mother had a bubble night-light with a glass tube of some kind of refrigerant that came unmounted, and I glued it back on with Loctite E-20NS, and that joint sits above a 7 watt light bulb and it has lasted years and is still fine. The unused tube has a limited shelf life.

Use drugstore 91 % alcohol on good quality paper towels to clean it up before it cures if it gets on anything.

Mark one side of the removable cap with a black sharpie and mark the same side of the tube so if you put the cap back in you do not cross contaminate the tubes.

McMaster-Carr has a special deal with UPS and they get a very low rate, and very fast shipping, and pass that low shipping cost on to there customers.


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You can reuse the gun for many years. The Loctite E-20HP is a great epoxy that sticks to anything ( but it will run ). it does have a limited shelf life.

The Devcon brand is also sold by McMaster-Carr and uses the same dispensing gun, and will stick to some hard to stick to plastics better than the Loctite brand, but the Loctite brand sticks to just about anything including practically all plastics, metals, and glass very very well. And the Devcon brand throws off toxic fumes. Frankly I do not want to have anything to do with the Devcon brand because the Loctite works sooooooo well and does not stink.
 
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I would ask a glass shop how much to remove your windshield, fix any issues with the area its to be attached to (rust) and reinstall.
Kinda doubt that's cost effective on a 1998 vehicle. $1,000+ for cutting out rust and restoring to new.
A tree limb could fall on it requiring replacement if you have glass coverage.
Few people carry comp and collision on older vehicles.
 
 
3M sells a urethane windshield adhesive product. You could try contacting them.
From 3M
The 3M Auto Glass Urethane is typically used for installing new glass windshields to the metal autobody. You could look at the 3M Auto Bedding and Glazing Compound. A flexible sealer designed specifically for creating a watertight seal between windshield rubber gaskets and auto bodies. This synthetic rubber-based sealer remains permanently soft, making it suitable as a bedding and a supplementary adhesive sealer for auto glass. It also resists sagging for use in vertical and overhead auto seals.
 
You can buy windshield urethane adhesive from any body supply shop. It not very expensive and comes in a tube that you use with a regular caulking gun. This is an example, 3M is generally the most expensive brand but the other brands work just as well.
 
You can buy windshield urethane at any parts store, but it's meant to be put down in a bead, then the glass placed on it. I guess just forcing it into the gap seems easy enough, but I'd bet on a mess and it still not being sealed.

Have you priced a windshield? I don't know what a first gen Expedition windshield runs, but I'd bet low hundreds installed at your home/job. Sometimes it's worth it to just pay $200-$300 and be done with something. I guess you could try forcing windshield urethane in it and cleaning up the mess, worst case it makes things harder for the glass company and they charge you more.
 
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