2011 E350 Exploding Sunroof
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Thanks for your concern.
I remember first hearing about this many years ago (from a BMW owner.) Do a search on E90Post.com. There is a rash of sunroofs exploding with BMWs (primarily 3 series.)
And then do a Google search under "my sunroof exploded" and you'll see that it can happen a lot and in all cars under the right circumstances. All brands.
Here's a good place to start. 8 pages worth of it happening beginning back in 2007 and affecting all brands of cars, including a E350 Mercedes: http://townhall-talk.edmunds.com/direct/view/.f1291fc/0
It's not the pano, but the standard sunroofs.
Thanks for your concern.
I remember first hearing about this many years ago (from a BMW owner.) Do a search on E90Post.com. There is a rash of sunroofs exploding with BMWs (primarily 3 series.)
And then do a Google search under "my sunroof exploded" and you'll see that it can happen a lot and in all cars under the right circumstances. All brands.
Here's a good place to start. 8 pages worth of it happening beginning back in 2007 and affecting all brands of cars, including a E350 Mercedes: http://townhall-talk.edmunds.com/direct/view/.f1291fc/0
It's not the pano, but the standard sunroofs.
I remember first hearing about this many years ago (from a BMW owner.) Do a search on E90Post.com. There is a rash of sunroofs exploding with BMWs (primarily 3 series.)
And then do a Google search under "my sunroof exploded" and you'll see that it can happen a lot and in all cars under the right circumstances. All brands.
Here's a good place to start. 8 pages worth of it happening beginning back in 2007 and affecting all brands of cars, including a E350 Mercedes: http://townhall-talk.edmunds.com/direct/view/.f1291fc/0
It's not the pano, but the standard sunroofs.
Last edited by RJC; Jun 23, 2011 at 09:19 PM.
My guess as to why it won't happen with a Pano is that the Pano's seam-lines/gaps are a little bit wider than the moonroof. Maybe in the event of some major temperature chance or effect, or some chassis flex, the standard sunroof is so tightly squeezed in by the steel around it, it has a higher probability to "pop"? The Pano roof has a large opening, and considerably spaced out gaps (at least between the glasses), in comparison.
It appears that the most common answer has to do with Bernoulli's Principal (or Bernoulli Effect.) Here's a layman's explanation from a physicist.
"Exploding sunroofs are not a manufacturer's defect. They occur when the sunroof is closed and the windows are rolled up. Manufacturers are very good at making the cabins airtight so the inside of the car will remain at the same cabin pressure while moving as when the car is sitting still.
When you are driving down the freeway at 65 mph, the air rushing across the top of the car creates lift (Bernoulli Effect). If you are driving against the wind you can also add wind speed to your traveling speed, and soon have pressure differences similar to a tornado. In addition, the specific day's barometric may also be a factor.
The glass is sucked upward and breaks, thereby equalizing the pressure. This instantaneous change in pressure halts the upward suction, and the remaining glass falls. Sunroofs are positioned nearer the windshield where air traveling over the car is traveling in an upward direction. It is not technically a manufacturer's defect, but it is certainly a type of design flaw. All cars with sunroofs should be have a pressure equalizer as found in modern airliners."
I'm assuming the small area of glass in a sunroof (versus a full pano roof) makes them more susceptible to being pulled upwards. I suppose it could be argued that lesser glass would be more susceptible to being sucked upwards and breakage, too. Although I'm also assuming that there are DOT regs on the type of glass (and strength) allowed.
It appears that the most common answer has to do with Bernoulli's Principal (or Bernoulli Effect.) Here's a layman's explanation from a physicist.
"Exploding sunroofs are not a manufacturer's defect. They occur when the sunroof is closed and the windows are rolled up. Manufacturers are very good at making the cabins airtight so the inside of the car will remain at the same cabin pressure while moving as when the car is sitting still.
When you are driving down the freeway at 65 mph, the air rushing across the top of the car creates lift (Bernoulli Effect). If you are driving against the wind you can also add wind speed to your traveling speed, and soon have pressure differences similar to a tornado. In addition, the specific day's barometric may also be a factor.
The glass is sucked upward and breaks, thereby equalizing the pressure. This instantaneous change in pressure halts the upward suction, and the remaining glass falls. Sunroofs are positioned nearer the windshield where air traveling over the car is traveling in an upward direction. It is not technically a manufacturer's defect, but it is certainly a type of design flaw. All cars with sunroofs should be have a pressure equalizer as found in modern airliners."
I'm assuming the small area of glass in a sunroof (versus a full pano roof) makes them more susceptible to being pulled upwards. I suppose it could be argued that lesser glass would be more susceptible to being sucked upwards and breakage, too. Although I'm also assuming that there are DOT regs on the type of glass (and strength) allowed.
It appears that the most common answer has to do with Bernoulli's Principal (or Bernoulli Effect.) Here's a layman's explanation from a physicist.
"Exploding sunroofs are not a manufacturer's defect. They occur when the sunroof is closed and the windows are rolled up. Manufacturers are very good at making the cabins airtight so the inside of the car will remain at the same cabin pressure while moving as when the car is sitting still.
When you are driving down the freeway at 65 mph, the air rushing across the top of the car creates lift (Bernoulli Effect). If you are driving against the wind you can also add wind speed to your traveling speed, and soon have pressure differences similar to a tornado. In addition, the specific day's barometric may also be a factor.
The glass is sucked upward and breaks, thereby equalizing the pressure. This instantaneous change in pressure halts the upward suction, and the remaining glass falls. Sunroofs are positioned nearer the windshield where air traveling over the car is traveling in an upward direction. It is not technically a manufacturer's defect, but it is certainly a type of design flaw. All cars with sunroofs should be have a pressure equalizer as found in modern airliners."
I'm assuming the small area of glass in a sunroof (versus a full pano roof) makes them more susceptible to being pulled upwards. I suppose it could be argued that lesser glass would be more susceptible to being sucked upwards and breakage, too. Although I'm also assuming that there are DOT regs on the type of glass (and strength) allowed.
A Chemist would of got it right. Tell the Physicist it's called a nickel sulfide inclusion. It may not be the most common answer but it is the "right" answer.
Side windows rarely explode like that even in heat. And yeah, then there's always heat stress and/or rapid cooling and the NiS inclusion can grow and rupture the molecular structure of the glass. But it seems ubiquitous with sunroofs in respect to other glass in the car.
But in the end it is kind of impossible to determine absolute cause of breakage (aside from the known NiS issue) since it happens quickly on the freeway and isn't quantitatively documented (it could easily be a tiny stone that the driver was unaware of in all of the exploding sunroof instances.) I think one would be correct in saying that the NiS issue is the only known variable, so you're certainly correct in bringing it up.




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