Here is what happened. Outside air temp about 50F, Escape had been driven about 10 miles, engine turned off for 10 minutes, then driven again. After driving about 1 mile or less while traveling about 45-50 miles per hour with no other traffic nearby I heard a loud pop (really loud). It wasn't safe to stop right away so I continued to my destination about another mile or so where I stopped to inspect the damage.

The passenger side rear cargo glass was shattered. The pieces didn't fall out or anything but the craze lines are throughout the entire piece of glass. It was only on the outer inch or so (beyond the glue line) where some fragments were actually lost. There is no evidence of a rock or other projectile being the cause. The reason I mentioned the air temp is that I had just turned the cabin heat on high briefly, I was going to the gym and just had changed into shorts/tshirt and wanted it a little warmer than usual. I don't see how that window would be subject to any thermal stress under those conditons however. Any ideas?

 

It wasn't thermal stress. My guess is that something hit it.

 

On further inspection during daylight hours I believe it was some sort of projectile, probably a bb or pellet gun. When viewed from the inside the craze lines are fairly uniform but do have a slight radial pattern that points to the upper rear corner of the glass.

When inspecting this area from the outside there is an apparent impact area that can be seen on the edge of the broken glass.

Oh well, at least my FEH glass isn't exploding for no reason.

Contact with the local police dept to follow....

 

Glass is a brittle rigid material. From time to time, a sheet of glass will be produced that has internal stresses and will shatter unexpectedly. Your window may well have been shot out but it may have spontaneously shattered. I've actually seen this happen to a car that was just backing out of a garage and the whole rear window just collapsed. It's pretty unusual but it does happen.

 

Hi,

My sister was visiting last winter and parked her relatively new Audi A3 on the street in front of my house. The next morning we found the passenger rear window broken in a similar way. Closer inspection also showed a few pot marks on the door itself. While we were looking at it, a neighbor a few houses down was doing the same thing with his mini van. It seemed someone went down the street that night shooting off a pellet gun. Lucky for you it was just the window as it can be replaced without it showing or needing paint!

On another note, my windshield spontaneously cracked the other day. I noticed it on the way to the airport so I'll deal with it next week, but not impressive. I'm sure it was not an impast as the crack came out from beneath the dash.

Cheers,

rcomeau

 

Glass can indeed have flaws that cause it to suddenly self-destruct. Several years back we had a Chrysler minivan that had the left rear side window "implode". It was sitting inside our garage at the time, so we're certain nothing hit it. It just imploded, crumbling into all the small bits tempered glass does, making a mess on the garage floor and inside the van.

 

I've seen a few windows implode in 20+ years of selling insurance. weather conditions and such. most newer vehicles are airtight and given the right conditions and one bump and a window will blow out. very rare though.

 

It is actually not air pressure that can trigger a window failure. Modern cars have an air extractor valve in the back that regulates internal air pressure, so your ears don't pop when you slam the door or turn the blower on high.

The fixed glass in a car is actually part of the body structure and is stressed in shear. So a motion that creates a twisting force on a car can increase the load on the glass. If the glass has a flaw or is in hard contact with metal in one spot creating a stress concentration, the window can crack.