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My rear window Exploded

Discussion in '3rd Gen 4Runners (1996-2002)' started by Hank69, Dec 6, 2022.

  1. Dec 6, 2022 at 8:46 PM
    #1
    Hank69

    Hank69 [OP] New Member

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    Hi all. I was driving to work the other day and I heard a pop (very loud) and then looked in my rear view mirror just in time to see my back window disintegrate.
    At first I thought someone might have took a shot at me on the freeway. However, I Googled it, and from a couple different pages and forums it turns out this is sort of a "thing" that happens. Something to do with the defroster wiring in the glass or something?
    Anyway, I was wondering if it would still be a problem now that I had a new piece of glass installed or should I just disconnect the defrost to be safe.? There are a couple of different opinions, but I thought I would ask y'all.
    Any wisdom would be much appreciated.
    Btw, on one of the pages I was looking at not sure which one, someone said they got a good deal from Glass America.
    I used them.
    It was $220 installed.
    $240 with tip.
    I'm definitely not super Automotive savvy but seemed like a good price.
    I was expecting quite a bit more.
     
    roboturner likes this.
  2. Dec 6, 2022 at 11:32 PM
    #2
    Trekker

    Trekker Regular Member

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    Don't disconnect your defrost, it's a safety item like mirrors or headlights.
     
  3. Dec 7, 2022 at 8:51 AM
    #3
    nimby

    nimby in the drink

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    Did you have your rear defroster on when it exploded?
     
  4. Dec 7, 2022 at 12:11 PM
    #4
    Overland WT

    Overland WT Grumpy Old Guy

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    Many with many more to go
    Just becasue it says so on the internet...

    Vibration
    Harmonics
    Direct heat
    Indirect cold
    Twist in the body during movement side to side
    Poorly tempered glass from the factory
    Cold outside, warm inside
    Any combination of these things

    There are so many possibilities, to even remotely try and narrow it down is impossible.
     
    negusm likes this.
  5. Dec 7, 2022 at 2:50 PM
    #5
    Tama1968

    Tama1968 New Member

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    weird. my co worker drives a 2016 Pilot and her rear glass popped like that, just sitting in the driveway. her husband is a retired corrections officer and first thought a member of his 'fan club" may have paid a visit but no evidence of gun play...
     
    mrmike7189 and Hank69[OP] like this.
  6. Dec 7, 2022 at 8:01 PM
    #6
    Hank69

    Hank69 [OP] New Member

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    The defroster was on.
    Not a particularly cold day.
    In response to one of the other replies about all of the countless things it could be...
    That is definitely true.
    I was searching for a consensus.
    After having spent almost 250 bucks, I would rather not take a chance without knowing more.
    And I am finding out there was a recall (outdated of course) for just this issue.
     
  7. Dec 7, 2022 at 8:14 PM
    #7
    Trekker

    Trekker Regular Member

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    This is a theory but if you put the window up and down a lot, it will scratch up the grid lines. If it happens that it only removes a bit of the paint, the paint that is left will heat up more because there is less conductive material (it's like using a 20 AWG wire in place of a 12 AWG wire, it heats up because it cant handle it).

    Now if you have a one part of your defrost heating up way more than the other parts, on a cold morning the difference in temperature will cause the window to break because of internal stress (like pouring boiling water on an icy windshield).

    When I repaired my back defrost with a paint kit, I painted the lines too thin. When I turned on my defrost, the parts I repaired got hot enough to burn me because they were too narrow. It didn't break my back window though, but considering how hot it got in a very specific area, I could see it causing an extreme amount of stress. I've never seen a window have it's grid line worn away in such a way that it causes hot spots where the paint is too thin.

    You can tell if it's heating unevenly because the rear defrost should remove the frost in a barcode pattern, if you see an area of the defrost line that has removed more frost than another part then you might have a hot spot. This is all a theory, but some parts of it I've experienced.

    I'll maintain my position though. Disabling something meant to allow you to see out your rear window is a bad idea. Check the defrost grid from time to time with a light probe, and you should be fine. Breaking a back window sucks, but merging into someone or backing into something because you cant see out your rear window sucks more.
     
    Last edited: Dec 7, 2022
    Hank69[OP] and roboturner like this.

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