Spontaneous rear window combustion (blowout) - PeachParts Mercedes-Benz Forum

Zacharias · #1 02-25-2012, 07:04 PM

Anyone ever had their rear window spontaneously blow out?

I was sitting at a traffic light a couple of hours ago when I heard a sound similar to a shotgun being discharged about 10 feet away and the rear window 'jigsawed' into hundreds of sections. It initially remained in place, but as soon as got out and shut the driver's door it began to implode.

Edits:

1. I ought to have said, "the exploding glass made a sound similar to...." I know what a pump action sounds like... if anyone shot at me, which I am now beginning to wonder about, it wasn't anything more than a pellet gun.

2. Anyone know if I am likely to find a rear window from a glass supplier? And cost? Or am I in for a visit to Uncle Merciless?

ChiefRider · #2 02-25-2012, 07:18 PM

I don't think I'd drive thru that neighborhood anymore.

Can't imagine that happening on its own.

Palangi · #3 02-25-2012, 07:28 PM

One of mine did that about 7 or 8 years ago.

Uneven rear window defroster, I think. Some of the elements were not working.

Scares the heck out of you when it happens, LOL.

Good opportunity to fix the rust under the gasket......

junqueyardjim · #4 02-25-2012, 07:47 PM

Well that happened to me about 5 years ago right now, with my 85 300D. Late winter and we get a lot of freezing rain here in central God's Country. So while I did my morning bus run, it got a nice build up of ice on it. I headed for home, turned the rear window defrost on and in about 5 to 7 minutes, KABOOM. This was while I was waiting for a traffic light. As soon as I opened the door, it all fell out, what a mess. I did read after the incident, in the owners manual, it said do not use the rear defrost under a buildup of ice. Now I know why. I did find a good rear window in the P&P, cut it out so I didn't break it, and found it easy to install using directions found here on the forum.

pawoSD · #5 02-25-2012, 08:16 PM

Is your car made out of rust? The fact it broke when you opened the door is scary.

Body mega flex?

compu_85 · #6 02-25-2012, 08:37 PM

The tempered glass was broken at that point. The pressure change from opening the door just sucked in the pieces.

-J

Junkman · #7 02-25-2012, 08:45 PM

Quote:

Originally Posted by Zacharias

2. Anyone know if I am likely to find a rear window from a glass supplier? And cost? Or am I in for a visit to Uncle Merciless?

I'd get the back glass from a yard. Take thee seal & everything. I've seen a couple of rear glasses that apparently popped out & were still intact as the result of the car being hit in the rear.

Make sure that the glass is pristine & not delaminated at all. Class gets cloudy when it begins to come apart. It will become worse once started.

Zacharias · #8 02-25-2012, 08:52 PM

Quote:

Originally Posted by compu_85

The tempered glass was broken at that point. The pressure change from opening the door just sucked in the pieces.

Ever heard a film sound effect of ice giving way? That's what this sounds like.

First the muffled BOOM and the initial failure, with the glass still intact but spider-webbed with cracks. Then silence for maybe 10 secs. Then the glass starts to fissure into fine cracks in a continuous muffled cracking sound. After maybe 30 seconds to a minute it's gone from semi-opaque to opaque, almost a frosted appearance.

By the time I opened the door and got out a few minutes later, it was just hanging in place (by the defroster wires, maybe?). When I shut the door the vibration and pressure differential were enough to collapse it onto the parcel shelf.

I have seen something similar happen in a car that was left parked for weeks in direct sunlight during a heatwave. In this case someone bumped the car and the window went.

I had several defroster wires out, but that was the case with every Mercedes I've driven in the winter. Wow.

ChiefRider · #9 02-25-2012, 09:25 PM

Quote:

Originally Posted by junqueyardjim

I did read after the incident, in the owners manual, it said do not use the rear defrost under a buildup of ice. Now I know why. .

Geez, I've done this hundreds of times with many different cars. Guess I won't do it with my 126!

Zacharias, was that the situation with yours, iced up and heating?

Hope you find a good use one- don't think new would be cheap!

Zacharias · #10 02-25-2012, 10:51 PM

Quote:

Originally Posted by ChiefRider

Zacharias, was that the situation with yours, iced up and heating?

No it was a clear day and I had just turned it off after minor defrosting on the inside (moisture buildup that had started to freeze as the temp had dropped while it was parked for half an hour).

Actually this unit was the weakest of any Mercedes I have owned. It could never have cleared ice on the outside, not even heavy snow, I tried once months ago then gave up on that idea.

Only a couple of wires weren't heating... about halfway up the glass.

compu_85 · #11 02-25-2012, 11:08 PM

I've had a couple cars with dead lines and never had an issue. I use it to clear ice too. Guess I've gotten lucky

-J

Zacharias · #12 02-26-2012, 12:14 AM

Quote:

Originally Posted by compu_85

I've had a couple cars with dead lines and never had an issue. I use it to clear ice too. Guess I've gotten lucky

No kidding.... My '79 SD cleared ice and snow better than this car, and I always read that the w116 had lousy rear defrosters compared to the later cars. I drove that car through four or five winters and never had an issue.

Both it and my '83 SD had several dead wires and worked just fine.

I guess it's a fluke? Oddly this car is the lowest-mileage and best-condition car of the lot.

The problem with looking for used in the yards around here is that I likely to find 'foggy' rear glass. I hate to install that on a nice car like this one.

Ask me how happy I am that I sent a 240d to the crusher two years ago with perfect glass

Stretch · #13 02-26-2012, 04:42 AM

Wow jolly bad luck old chap...

X2 on the junkyard replacement - though Canada seems a bit hit and miss with old Mercedes parts from what I read... It might be worthwhile asking the normal windscreen repair shops... at least if the quotes are silly you can be safe in the knowledge that you are saving mega bucks by doing it yourself.

PeachPartsWiki: Rear Window Seal Replacement

Though I've not tried them myself - rumour has it that non dealer seals are a waste of time (if you plan to fit a new seal that is)

Biodiesel300TD · #14 02-26-2012, 10:09 AM

I've not had it happen in a car, but a window in my parents house did that while I was in high school. It's from the flexing of all the material during temperature changes. Tempered glass will shatter with the slightest tap if you hit it on the edge in just the right spot.

I too would find a junkyard specimen. When was replacing my rear window seal I called around for a new one with defrost, people wanted upwards of $600 for it. I think the cheapest was $350. That was just for the glass no install.

Zacharias · #15 02-26-2012, 11:41 AM

Problem with used is that the only PnP with any intact w123s is only open Monday to Friday, bank hours, and it's currently -15 C here. So that suggests paying a yard for used, which will likely be $100-200. I do have a friend a couple of hours away who has parted a couple of w123s in the past, but I don't know if he kept any glass... can't reach him today he's probably off skiing somewhere.

However, I just stumbled upon this NOS for $250:
Original Mercedes Rear Glass - W123 - City of Toronto Other Parts, Accessories For Sale - Kijiji City of Toronto Canada.

Toronto is about 400 kms from me, but cheap to ship stuff via intercity bus.

I've fired them off an email and have my fingers crossed....