Rear hatch glass shattered suddenly for no reason

[TouringFan]

Last week, I got into my 2023 CX-5 Signature Turbo to run errands and when I shut my driver's door, the rear hatch glass shattered into a million pieces. When I called my dealer to figure out what to do and find out if this was covered under warranty, they were not much help. The service manager told me glass breakage is not covered under warranty and that it is too difficult for them to know if it truly happened by itself or if it was due to vandalism. When he checked availability for new rear hatch glass, he was told this part is backordered in the US with no known delivery date. I find that curious. If mine is an isolated incident, why is this part backordered indefinitely? Fortunately, Safelite had rear hatch glass in stock and $200 later, my CX-5 was fixed.

Has anyone else had this problem?

 

[CarpeDiem]

…If mine is an isolated incident, why is this part backordered indefinitely?…

If breakage is extremely rare then dealers may not bother to stock replacements. Inventory sitting for years costs money. The window likely broke due to the pressure spike as you slammed the door. What weakened the glass to make it susceptible to break will never be known, but it didn’t happen “for no reason”. How old is the CX?

 

[TouringFan]

My CX is 10 months old with only 5000 miles on it. I suggested to the Mazda service manager that the pressure spike from shutting the driver door with more than normal force was part of the problem and he basically laughed at me. I do have to shut the door with more than normal force because it does not latch completely with a light touch. It is either misaligned or the tolerances with the rubber door seal are off a bit. The service manager told me he has never seen rear glass break from a pressure spike due to slamming a door shut. I haven't either but I am an engineer that does all of my own maintenance and have done so for 50 years. If there was a flaw in how the glass was installed that put uneven stress on the glass, then over time, the pressure spikes could definitely have caused the failure. All materials degrade over time from repeated stress cycles. The metal structures on our cars are designed to have a life span that takes into account stress cycles if designed properly. Glass parts are also designed this way but if the stresses on the glass are not what was envisioned due to flaws then the part will not meet its lifespan as designed. Difficult to prove this and so the dealer will not help with a warranty claim.

 

[TouringFan]

I have done reliability engineering for Navy aircraft and catapults and arresting gear on our aircraft carriers. I know from experience how strength of materials and expected stresses are taken into account during the design phase. It is pretty clear to me that whatever the cause, the stresses on my rear hatch glass were not what was expected by the designers. It could have been a flaw in the glass or installation flaw that put more stress in a specific location than the material could tolerate over time. It could also have been a tiny chip from a stone that created a concentrated stress point that grew over time. This is what happens when a stone chip in a windshield grows into a large crack if not repaired right away. I think a stone chip in the rear glass is not very likely but concede it is possible.

Failures due to stress do not happen suddenly but occur over time and exposure to repeated stresses. There is a particularly famous example of this in the BMW world. the E36 and E46 3 Series models are known for catastrophic failures of the unibody structure where the subfame that carries the rear differential is bolted to the floor of the car. As these cars age, there have been many many reports of the rear floor developing cracks and eventually tearing completely where the subframe is attached. BMW has never admitted that their design was flawed but they have manufactured reinforcing plates that have to be welded to the car in the affected locations. It is a very expensive repair and not covered under any warranty.

 

[yrwei52]

My CX is 10 months old with only 5000 miles on it. I suggested to the Mazda service manager that the pressure spike from shutting the driver door with more than normal force was part of the problem and he basically laughed at me. I do have to shut the door with more than normal force because it does not latch completely with a light touch. It is either misaligned or the tolerances with the rubber door seal are off a bit. The service manager told me he has never seen rear glass break from a pressure spike due to slamming a door shut. I haven't either but I am an engineer that does all of my own maintenance and have done so for 50 years. If there was a flaw in how the glass was installed that put uneven stress on the glass, then over time, the pressure spikes could definitely have caused the failure. All materials degrade over time from repeated stress cycles. The metal structures on our cars are designed to have a life span that takes into account stress cycles if designed properly. Glass parts are also designed this way but if the stresses on the glass are not what was envisioned due to flaws then the part will not meet its lifespan as designed. Difficult to prove this and so the dealer will not help with a warranty claim.

You certainly can call Mazda North American Operations and complain with all you said here. Especially you should complain about the rear window shortage in the US, which isn’t acceptable. Who will drive a car without the rear window? And luckily the Safelite has it but that’s something you can tell the rep that this’s something you really didn’t like as you preferred OEM rear window, but you had no choice but settled for the aftermarket window glass.

 

[erhayes]

I would also ask that the replacement glass be covered. Divining without the rear glass is a real safety issue due to exhaust intrusion.

 

[TouringFan]

Thanks for all the comments and suggestions. I would like to repeat that the rear hatch glass was not just out of stock at the dealership - it was out of stock in all Mazda USA warehouses. That is what I found so curious. If mine is an isolated incident, why are there no parts available in this country through the dealer network?

 

[yrwei52]

Thanks for all the comments and suggestions. I would like to repeat that the rear hatch glass was not just out of stock at the dealership - it was out of stock in all Mazda USA warehouses. That is what I found so curious. If mine is an isolated incident, why are there no parts available in this country through the dealer network?

I understand your feeling that why the rear liftgate window is in shortage in the US and you couldn’t even order one with a date? Pandemic can’t be the excuse now. I know the rear liftgate on CX-5 was out of stock in the whole US for a while last year, not sure what the current situation is. I stopped by a Toyota dealer at the time and the parts guy told me they had similar situation on RAV4 for a while because of the pandemic but the supply has back to normal now.

Due to the very frequent break-ins to the rear quarter window in San Francisco Bay Area and that piece of glass is also in very tight supply in recent years. When my daughter’s 2022 Toyota Corolla Hatchback rear quarter window on rear door got smashed earlier this year, only a few local Bay Area Toyota dealers stocked that glass, but they all could get one from Toyota warehouse within a day if they didn’t have one in stock.

 

[7eregrine]

If mine is an isolated incident, why are there no parts available in this country through the dealer network?

I mean, thiss answer the question you asked. This is an isolated incident so why would they carry it? I absolutely see both sides...it's bulls*** that it happened. If it happened as you say, and I believe it did, it's clearly a defect. But I see their side too...no way they can truly know how it broke. And being not common...

 

[1killera4]

Note for the future. Always make sure your AC is not on RECIRC when leaving your vehicle in the summer months. Had this happen on my first Audi (2008)and that's what they told me. Since then, never an issue. With the increased sealing on the CX 5 Doors to combat noise intrusion and better sealing I would be inclined to think this may be part of your "root cause". I could do a 5 why if you need. LOL

 

[ruthrj]

Note for the future. Always make sure your AC is not on RECIRC when leaving your vehicle in the summer months. Had this happen on my first Audi (2008)and that's what they told me. Since then, never an issue. With the increased sealing on the CX 5 Doors to combat noise intrusion and better sealing I would be inclined to think this may be part of your "root cause". I could do a 5 why if you need. LOL

Lol, love your 5 Y comment.

I’d be worried that the little hidden vent in the rear cargo area is stuck. If you slam your car door or run the AC with outdoor air supplied, a vent in the rear of the car should allow pressure to exit the vehicle.

 

[TouringFan]

@1killera4, love the 5 why comment too. Thanks for the suggestion. It never occurred to me that leaving AC on recirc could be the cause and I am sure it was left in that setting.

 

[Martyd]

Note for the future. Always make sure your AC is not on RECIRC when leaving your vehicle in the summer months. Had this happen on my first Audi (2008)and that's what they told me. Since then, never an issue. With the increased sealing on the CX 5 Doors to combat noise intrusion and better sealing I would be inclined to think this may be part of your "root cause". I could do a 5 why if you need. LOL

Are you suggesting that there was a build up of pressure and it popped the window? I know there are rear vents and I'm having trouble believing this could be a cause.

 

[TouringFan]

The fact is that it shattered when I slammed my driver's door shut. Draw your own conclusion.

 

[jadmt]

I guess it is lucky we don't blow our eardrums out...I think it was probably more caused by either a manufacturer defect in the glass or a small nick maybe during installation around the hole for the wiper than from pressure. I never shut my recirc off and plenty of over 100F days here. Be interesting to see if there is a rash of these. You can post on the nhtsa site. seems if enough incidents they should issue a safety recall.

 

[ruthrj]

It’s definitely some combination of factors where the door slam acted as the catalyst (either by pressure or vibration). Safelite tells you not to close your door within 24 hrs of windshield installation without first opening a window some. They don’t want you to blow out the wet window seal before it dries.

 

[wlong01]

I guess it is lucky we don't blow our eardrums out...I think it was probably more caused by either a manufacturer defect in the glass or a small nick maybe during installation around the hole for the wiper than from pressure. I never shut my recirc off and plenty of over 100F days here. Be interesting to see if there is a rash of these. You can post on the nhtsa site. seems if enough incidents they should issue a safety recall.

I'm sure if that was the case they're be plenty of pissed off CX-5 owners in TX, AZ, NV, FL, etc.

 

[hooked]

I’ve lived in S. Florida for decades and always have the AC set to recirculate and never had a blown out window because of the heat. I did have the rear window shatter but not break on my Honda Accord a few years back but that was during a cool morning with the rear defrost on. There must have been some sort of short in the defrost because I had the rear glass replaced and it happened again a few days later. I had the installer not hook up the defrost connection to the second replacement.

 

[1killera4]

 

[1killera4]

I’ve lived in S. Florida for decades and always have the AC set to recirculate and never had a blown out window because of the heat. I did have the rear window shatter but not break on my Honda Accord a few years back but that was during a cool morning with the rear defrost on. There must have been some sort of short in the defrost because I had the rear glass replaced and it happened again a few days later. I had the installer not hook up the defrost connection to the second replacement.

So, since it never happened to you I guess it couldn't happen to anyone else? Do you see the flaw in that line of thinking? Now, before you answer, I live in Florida too...and it happened to me. There are many things that can cause a window shatter in extreme heat. In my above post you will find an example of an Ishikawa Diagram (Fishbone Analysis), fill that out and find out.
Enjoy your day.