I have heard of rear windows exploding when the rear defroster (electric) is ON and it fails to shut off.

The only logical explanation I would have...
1- someone or something hit the window. You may not hear the glass being hit and it shattering, 'cause there isn't enough time difference between the two events.
2- the window was under a lot of stress by the window mechanism - does it have electric window lifts? It may have overstressed the window pane and a little extra vibration can shatter the glass.
3- poor quality glass

my buddys drivers side window in his dodge pickup, exploded while he was sitting in his drive. i was in the passengers seat. didnt see or hear anything hit it. the glass company that replaced it said it happened because of a worn channel, that put a strain on the glass.

This is indeed unusual.
Hope no-one ended up with any glass in their eyes ..
I think this is caused by a sharp stone or piece of debris being thrown up by a passing vehicle.
All cars should have "mud-flaps" to prevent this..

On most vehicles only the windshield is made with the laminated vinyl center section to keep it from disentegrating (exploding)when broken, side windows will as you say EXPLODE, sometimes very little is needed to break it. I shattered one myself several years ago I was putting a chainsaw into the front seat of my old farm truck and the window was about two inches up the chainsaw hung and the window exploded dang it. Your incident could have been a BB or pellet from a kids gun! I think I would call the police and report it, that way if they start to see a rash of broken windows in this area maybe they can get it stopped. In my local area (not considered a bad area) the local fire trucks have become target practice with over 25 incidents in the last couple of months and everyone has heard of the rocks being thrown from overpasses by stupid kids, people are doing real stupid things out there, drive careful.

I exploded a side window in a mini van afew years when a weedeater caught a rock ang shot it at the window - it doesn't take much I understand. Needeless to say, I moved the cars or was extra careful not to catch rocks when trimming the edges. Your comprehensive should cover that (maybe don't tell them you did it??).

A falling green walnut hit my daughter's windshield last fall. Nothing like a new shield on a 8 year old car - they do become "sandblasted" after 140K miles..
No problem with her comprehensive paying for a replacement..

We had to pay the $200 deductible, but at least it is fixed now. I still have some glass shards on the dash that I will have to clean up. The glass guy said it was very odd that it just up and shattered, and that we probably would have heard something if there was a hit. Oh well, it's over and done with and nothing can be done about it. Just glad I was facing the other way and didnt' end up with glass in my face. Thanks for all your input everyone.

Glenda

I saw, or actually heard that happen to a car sitting in the shop I was working in in the 70's. A mechanic brought the car in and parked it in his stall. Myself, the service writer, and a number of other employees were over by the parts counter when we heard this bang. The passenger side window in that car had just shattered. The vehicle was parked inside and nobody was anywhere near it. We had no idea how or why it broke. Service writer said it must have just been bad glass. It was the passenger side door glass in a late 70's pontiac firebird.

I looked at one of the new Mustangs the other day the door windows are made without a frame at the top. When you open the door the window automatically rolls down about 1 inch then once you close the door the window automatically jams up tight. The salesman told me that Ford designed it that way for two reasons 1. It makes a better seal 2.The window can roll up to far and be in a bind and shatter since the top kinda floats out in space. hmm

How to completely confuse your insurance agent:

I was driving my Wrangler soft top home from work in one of the South's infamous ice storms. Had about 2 inches of ice on the rear side windows that I didn't feel like waiting to melt off (can't use an ice scraper on a plastic window). So I'm on the highway and an 18 wheeler passes me and throws up a huge chunk of ice into the driver side rear window. It shattered just like glass! Also scared the bejeesis out of me. When I called the insurance company, he said "broken window- take it to a glass shop" and connected me right away before I could say anything. Talk to the glass shop- which of course does not replace plastic windows. Called insurance company again- quickly explained that my PLASTIC window broke and the GLASS shop can't fix it. Stunned silence. Ended up writing me a check and I got a new aftermarket window.

Posted by: earthworm (My Page) on Mon, Mar 21, 05 at 20:15

This is indeed unusual.
Hope no-one ended up with any glass in their eyes ..
I think this is caused by a sharp stone or piece of debris being thrown up by a passing vehicle.
All cars should have "mud-flaps" to prevent this..
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Yea, mud flaps would look really cool on my vette, or better still on my neighbors Ferrari !!

Mudflaps seem to only work in protecting rock throws toward the rear. They do nothing about side rock throws. :-(

This is an older thread, but I happened across it while looking for something else and thought to add a few cents worth.

The side windows of your car are tempered glass. Tempered glass is heat strengthened by taking the glass up to 1200F and then rapidly cooling it. This causes the exterior surface of the glass to compress while the interior of the glass is still quite warm and still in expansion mode. Ultimately, this translates into an exterior compression layer and an interior tension layer.

When the compression layer is breached, then all that tension is released (kind of like a spring) and POW! there goes the window.

Okay, then why did the side window break? It is certainly possible that it was impacted by a rock or bb or something similar, but I am guessing that it was spontaneous breakage based on the description.

As mentioned, tempered glass is tough on the face, but the edges are quite fragile.

One characteristic of tempered glass is that if it has edge damage it might not "release" immediately, preferring to wait around for awhile until it has a chnace to scare the @$#%@^@%#$@ out of someone sitting at a stoplight or else eating breakfast in their home. It makes for great conversation!

When glass is manufactured, it might have what are called "inclusions". Usually nickle sulfide or perhaps other trace elements, these inclusions can cause significant problems in tempered glass. While most glass with inclusions will break during the tempering process, some of them are just stubborn enoungh to make it past that process and into the actual finished product. These inclusions, like their edge damaged cousins, love to wait around awhile until everyone is quietly relaxing and then POW! no more glass in the window frame.

Typical breaking stress for annealed (regular) glass is around 6000psi. Typical windload breaking stress for tempered glass is around 24,000psi, thus the "four times stronger" comparison that many folks like to quote.
When impacted, tmepered glass is about double the strength of annealed glass. One typical lab test is to impact 1/4" lites with a 5gm missile. The tempered glass can withstand the impact up to about 60ft/sec while the annealed can withstand the missile to about 30ft/sec.

Ultimately, very few folks insure against glass breakage. Although spontaneous breakage does happen, I would suggest that proving it will be difficult and the last thing that any glass company wants to do is to deal with about 10,000,000 claims for spontaneous breakage - definitely a losing situation. And realistically, way more glass is broken for reasons other than spontaneous breakage...

Hopefully this made some sense!

I too have a 5 yr old PT Cruiser that just experienced a similar thing.

I was sitting at a stoplight in the left turn bay, when all of a sudden...BOOM! Almost my entire back window was gone. The guy in the car next to (and slightly behind) me had his mouth open and a stunned look on his face. He asked ME what happened!

There were was another witness from the car behind me who just shrugged his shoulders when asked what happened.
Initially, many things went through my mind:

1. Did somebody with a baseball bat and smash my window and run off? --No. He would have been seen.
2. How about a kicked up rock from a passing car? --No. All cars around me were at a standstill and there was no oncoming traffic.
3. Maybe I was shot at by a gun or BB-rifle? --Unlikely. The intersection is in the middle of an open field, so there is no place to hide. Plus a handgun or rifle shot would have hit something else in my car when the bullet passed through. I've seen windows that were broken by a small projectile and usually you can easily define the impact spot. There was no such spot.
4. Did something fall off of an airplane and hit my window? (I actually did look up at the sky after exhausting all of the other possibilities.) --No. I looked over every inch of the car and could find no trace of a projectile.

When I took my car to the police station, they said that since it wasn't vandalism or caused by an accident, that they "really didn't have a form for spontaneously exploding car windows." She did tell me that she has heard of this happening on 4 different occasions before.

SO WHAT REALLY HAPPENED?
I'm guessing that it was a combination of several events:

1. A big storm was rolling in at the time so the pressure was dropping
2. It was a warm day, but the storm was bringing with it much cooler air
3. I had had my car serviced the week before at the dealer for problems with my rear window washer fluid dispenser, which actually sits on the rear window glass

EVIDENCE
The only evidence I have is a lack of a projectile and the broken glass was about 60% inside my car, 40% outside...suggesting that the window just exploded.
I've attached a link to some pictures that I'll post later tonight.

Scary and wierd!

Here is a link that might be useful: Pictures of exploded car window

When a side glass explodes just sitting there it is usually because the glass was tempered wrong. When I worked for General Motors we would get a shipment of glass that was tempered wrong. And there would be glass popping for a couple of days. Usually when we did the fit for seal operation. That was when the glass was being adjusted to fit the weather strip for a seal. But sometimes when you were just walking pass a unit the glass would explode (and scare the hell out of you) just from the stress of sitting in the door. I have seen literary thousands of them explode.

I have a friend that owns a body shop. He had a customers car in to replace a side glass that had exploded. The car was finished and parked out side in front of the shop around 3:30pm. The customer showed up around 4:00pm walked into the shop and asked when the car was going to be finished. The owner said it was all done and ready to go. When they walked outside to inspect the new glass that one had exploded too. So it is not uncommon for them to explode. But I don't think they are as bad as they use to be.

I drive a 2004 Pontiac 2004 Vibe - very similar to the PT Cruiser. I had just gotten back from lunch, car was in park and I was rolling up my window. It burst and exploded everywhere. Now the dealership is saying it's probably not covered under warranty. So the bumper to bumper warranties are literally no good. What a joke.

I had this same thing happen to me last night. I drive a C70 Volvo Convertible. It was also my driver's side back window. I agree, it scared the $%$%%$%$ out of me and my son who was also in the car.

This happened to my Dad while driving a late 80's or early 90's Dodge Caravan...can't remember the exact year. He was just driving and BAM, the driver side rear back window just exploded. Seems more common than we realize, I guess.

BN

This happened to me last night. I was backing my minivan up and put it into drive, and BAM!, the passenger rear side window exploded. Scared the crap out of me and my passenger. I was so confused, I hit nothing, and nothing hit me. Although it is comforting that I'm not crazy and that others have experienced having their windows explode, I want to know WHY!

Add me to the club. I got into my car went to roll the window down and smash glass everywhere. It even ended up across the street. I just had tgey gears to roll the window up and down replaced so I know why mine happened