Sealant on new windshield?

[z71se]

Hey guys I have a new Precision windshield gasket and new PGW windshield. I'm familiar with the install procedure for the glass, but my question is regarding sealant. Most say no, some say yes! Apparently, GM issued a TSB for early square bodies that didn't originally have sealant, but I believe that was a safety concern versus a leaking windshield concern.

If you do recommend sealant, what kind? I'm not concerned with sealant on the paint and getting it off. I'll paint this truck eventually and when I do, a bit of dried silicone will be the least of my concerns.

[broey]

I don't see any need for it. the whole point of the precision rubber gasket is to not need sealant. seems like overkill.

[68JOHNDEERE]

I always preferred the 1 time insurance policy of sealing any install I did, water inside the cab is never a good thing.

Both products I use are made by 3M, Glazing & Bedding compound is a non hardening sealant used between the body and gasket. After the glass is in the gasket before the locking strip use Window Weld which is a urethane sealant placed between the glass and the gasket.

https://youtu.be/LsSB4Kad4qA this video gives you an idea where the sealants go.

[Bandit130]

I will be replacing my windshield in a few months. Several youtube videos show installation and none of them mention any type of sealer.

[z71se]

I made a post on the Facebook square body groups, and the consensus was to use urethane sealer, both at the gasket to cab junction, and the glass to seal junction. GM actually issued a TSB in the early 80s that mandated that any glass replacements on early square bodies had to have urethane sealant. That had to do with a safety issue (glass flying out during an accident), but many people have said that they installed a new windshield and new gasket, and had it leak. Their glass guy then came out and added urethane sealer in the aforementioned places, and leaks were cured. So, I will be using urethane sealant on mine, 3M part # 08609. The 3M Glazing and Bedding compound is not advised. This is what the glass shop that sold me the glass recommends:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Justins76]

If you use sealant, you can't ruse the gasket. I have my window cracked so often that I just have the glass replaced using the same gasket.

[z71se]

Originally Posted by Justins76

If you use sealant, you can't ruse the gasket. I have my window cracked so often that I just have the glass replaced using the same gasket.

In my eyes, the gasket is relatively inexpensive, only $40 for a good Precision brand. If my windshield cracks, I'll be happy to replace the gasket in order to get a leak free seal.

[Bandit130]

Originally Posted by Justins76

If you use sealant, you can't ruse the gasket. I have my window cracked so often that I just have the glass replaced using the same gasket.

When you re-use gasket, have you had leaks?

[z71se]

Originally Posted by Bandit130

When you re-use gasket, have you had leaks?

Depends if it's a 1-week old Precision gasket, or a 45 yr old original. I really don't understand the logic of not replacing the gasket. Every time the glass goes in and out, you risk cracking it.

[andyh1956]

I just stripped an '84 cab & it had sealant between gasket & body lip.
I had a little 3M sealer gun that looked like a long snout oil can that you applied the sealant behind the gasket with, but it's long gone now.

[Justins76]

Originally Posted by Bandit130

When you re-use gasket, have you had leaks?

No leaks. The safelite glass tech even recommending not replacing the gasket last time. He said it looked fine and I would be wasting money replacing it. I just have the locking strip replaced since the chrome turns brown after a year. Not sure if its original, but its at least 30 years old.

[Justins76]

Originally Posted by z71se

Depends if it's a 1-week old Precision gasket, or a 45 yr old original. I really don't understand the logic of not replacing the gasket. Every time the glass goes in and out, you risk cracking it.

I only time my glass comes out is when its cracked already. And thats every few years.

[andyh1956]

Around here windshields are Consumables like Brake Pads!

[tucsonjwt]

My 73, 76, and 83 squares all leaked around the windshield. The sheet metal around the windshield opening was crimped at the upper and lower corners at the factory and all of my trucks had bad crimps, so they all leaked. The fix for me was to have the windshield installer tap down the raised up sheet metal then use sealant, which stopped the leaking. So, I will always require sealant when new windshields are installed.

[z71se]

I had the glass guy come out, this guy only works on pre 1995 stuff, and is the go to for all Classic Chevy’s in the area. He even does custom glass and also rebuilds vent window assemblies. He used plenty of urethane and said it’s the only way to guarantee a leak free fit. He also said it would be no problem for him to save the glass if I need to remove it for paint.

[Sabaka454]

Installers are required to use urethane sealant on windshield installations.

[z71se]

Originally Posted by Sabaka454

Installers are required to use urethane sealant on windshield installations.

Yes and no. If you call up Safelite or another corporate type windshield business, sure they'll be by the book. This guy that works on classics said he'd do it with peanut butter if I wanted, it was really up to me but he recommended the glue so he wouldn't have to come out and do it again because he said more often than not on these C10's there is some sort of small wind leak or water leak and the glue fixes all of that.

[tucsonjwt]

I have found that the aftermarket chrome lockstrip turns brown in about 2 weeks in the desert southwest. I bought a black lockstrip from LMC but will be using the standard no lockstrip weatherstrip when I have the windshield replaced after paint and body work is done. Aside from initial appearance, I don't know why GM when with the lockstrip style weatherstrip.

[z71se]

It’s a real shame because the factory original lasted a whole lot longer
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