R172 Cracked Windscreen

[E55BOF]

A crack has appeared in my windscreen. One day it wasn't there, the next day it was.







It is right up in the top left corner, so it is not a vision obstruction. The odd thing is, if I run my finger over it on the otuside, I feel absolutely nothing - no chip, no raised edge or gap, nothing. I can feel the crack only on the inside. There has definitely not been any impact on the inside of the screen in my ownership, and it wasn't there when I bought the car.

This is a new one on me. Does anyone have any idea how it could have happened? Could it have been a stress point in the inner glass layer which has finally given way after 50K miles? (No, I'm not looking to approach MB for anything; I'd just like to know if it has happened to anyone else).

 

[Will]

Do you know if it’s the original screen or has it been replaced at some point?

 

[oldguy57]

I have seen this before. A stress fracture -happened to a friend's BMW when he ran into a pothole. Apparently it had been a cheap replacement screen.

 

[zipdip]

Well it s too far up the screen for a stone chip,my suggestion is that someone has hit the screen at the point where the two cracks meet and did it as they went past from back to front of the car so the the blow was angled down and so the cracks went down

 

[poormansporsche]

Gutting on a new to you car

My suggestion would be it's exactly the spot where the squeegee gorillas lean when cleaning the roof.

 

[st13phil]

Could it have been a stress point in the inner glass layer which has finally given way after 50K miles?

It's certainly a possibility. It would be worth looking at the very edge of the inner lamination of the screen when it's removed. I wouldn't be surprised if there was either a small defect or evidence of a chip right at the end of one of those cracks that's acted as a stress concentrator.

 

[E55BOF]

The screen has the MB logo, and was made by OE supplier Pilkington, but there's no MB part number, so my guess is that it's aftermarket.

I very much doubt that squegee gorillas have ever laid a hand on this car. Besides, the crack is only in the inner layer, and I doubt the screen would have flexed enough under pressure not to crack the outer layer as well. The only thing I can be pretty sure of, though, is that it's not impact damage.

 

[m80]

Most likely a stone chip.
I've got one higher than that on the Viano.

They've been laying roads round here and it wasn't there before I was doing 20mph on one and keeping a great distance from cars ahead. I didn't feel the impact but it's there, and I don't think it's coincidence.

 

[E55BOF]

It's not a stone chip, I reckon; only the inner layer of the laminated windscreen is cracked.

 

[Will]

The reason I wonder about replacement is that sometimes it doesn’t take a lot to crack a piece of glass, think about how tiles can be scored and snapped over a matchstick etc. A crumb of broken glass where it’s fitted to the frame or a lump of old adhesive with debris stuck to it and it may sit there for some time before an additional stress - eg sudden flexing through driving, or heat etc?

I’m only speculating of course but if it’s a replacement screen then this sort of scenario is more likely, especially with no visible impact damage.

 

[st13phil]

Well, well, well...

I moved Angie's R172 SLK55 off the drive yesterday and the windscreen was fine. This morning I came to use the car and found this:

Just like @E55BOF, the crack is on the inner lamination not the outer, and neither end extends to the edge of the screen. There is no sign of impact damage anywhere along or adjacent to the crack. Here's a view from inside the car:

Very, very, odd.

 

[MEMERC7]

I have small crack in front of sensor box (SLC). Let us know how you all get on with having the screen replaced & how efficient the process was. I believe the screens included a radio aerial & of course the sensor box has to be removed/replaced. Not a job the some cowboy on your driveway so maybe it has to be a Mercedes stealer job - hope I'm wrong.

 

[st13phil]

I believe the screens included a radio aerial & of course the sensor box has to be removed/replaced.

It does and it does, in that order

Let us know how you all get on with having the screen replaced & how efficient the process was.

I've booked Angie's car in with National Windscreens at their depot as they say it requires camera calibration after fitting (the car has ILS and Speed Limit Assist). They did a great job when they replaced the screen on my E63 and that had the stereo cameras as it had the full Driver Assistance Package. Hopefully, they'll be as good with the SLK55.

 

[E55BOF]

My crack Ooops The crack on my car isn't in an MoT fail position, so it would only be a minor ("Failure for damage is only justified if the damage significantly affects the driver’s view of the road". Where it is, it would only affect my view of a low-flying aircraft...). I'm just going to leave it -for now- and see if it develops.

Is there an MB part number in the bottom left corner of an OE screen, does anyone know? If so, Phil, is yours a Pilkington (aftermarket) screen too, or an OE one?

 

[m80]

You've reminded me, so I've just been out to polish and check.
Mrs Me's 211 has 5 pin ***** chips. You would struggle to se them if not looking.
I perceive that the screen isn't significantly weakened.

Mine has 2 puddle like damages, each less than 0.5mm. I can imagine they becoming a crack easily.
So to the Auto glass site for an idea of repair and cost. Repair no issue by the looks, 1st repair £215.15 (incl vat), 2nd would be quoted for. That's a surprise.

Anyways I've checked my LV insurance, the y may increase the premium next year, but the NCD will be unaffected. So I'll compare renewals at that time, and do it early cos they sting you if you leave it close to renewal.

All booked online with Auto Glass, between 8 an 12 noon tomorrow. £20 paid online.

Thanks for the reminder.

 

[st13phil]

Is there an MB part number in the bottom left corner of an OE screen, does anyone know? If so, Phil, is yours a Pilkington (aftermarket) screen too, or an OE one?

I know with certainty that the screen in the car hasn't been replaced and is what came from the factory. It's a Pilkington screen. Here are the markings on it...

Right:

Left:

 

[st13phil]

Incidentally, the 5 dots & the number "15" are the date code indicating when the glass was manufactured. The number is the year (2015) and the 5 dots preceding it indicate month #5, i.e. May. This ties in with the production date of the car.

If the dots were after the number, you would add 6 to the number of dots to get the month, e.g. 2 dots to the right of the number would indicate month #8, i.e. August.

 

[E55BOF]

Mine's an OE screen too - founder's signature bottom right; I hadn't looked there. Mine's been replaced, though - *****15, so made in the same batch as yours.

 

[ToeKnee]

That's interesting and just looked at my screen. No markings on the left (drivers side) but markings on the right, no signature but there is a Mercedes symbol and 5 dots 15 and three more dots starting under the 15 going to the right. If 15 is the production date then my car has had a new screen! Interesting.

 

[merc estate]

Let us know how you get on with autoglass and national windscreens, it will be interesting to know how iit goes with them.