My friend's Acura RL has a 1-ft long crack starting from the right edge
of the front windshield, about halfway up the windshield. It's roughly
horizontal, with some up and down deviations, but no "spider web" or
"sunburst" cracks at all! He noticed it after the car was parked in a
parking lot. What could have caused that??? He thinks it was vandalism.
The most common cause is the effect of temperature changes when there is a
rock pit in the glass. I moved to cold country about 5 years ago and learned
cold nights cause most of the cracks here. Our Toyota dealer made the
determination whether our windshield crack was a defect covered under
warranty or damage to report to our insurance by running a ballpoint pen
along the crack. It hung up in a pit, indicating it was damage that had
grown into a crack... no warranty. It ran from the bottom edge near the
driver to the left edge and appeared when we washed the car after it had
been sitting in the sun.
As TeGGeR often points out, it is important to be sure it was not rust of
the weld around the windshield that did it, because the next windshield will
suffer the same fate if the rust isn't repaired.
cracked windshield was clean!) and it spread several inches per second once
it got started.
On a related subject we took a cab in Mexico (Puerto Vallarta? I forget)
recently and I noticed there were several nearly complete circular cracks,
about an inch in diameter, in the windshield. As I pondered what caused
those, I realized there was a more normal crack that ended inside each of
the circular ones. Then the light came on - the circular ones were made
purposely to stop the spread of the normal cracks... like stop-drilling
them. It still looked weird.
Our 04 RX330 had a stress fracture crack. The dealer determined it
wasn't due to a rock chip, vandalism or anything like that and
replaced it under warranty.
So, if the crack is really smooth from the side of the windshield to
the end of the crack, there is a chance it could be a stress fracture.
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