Front windshield gasket shenanigans!

[daantjie]

Hi Guys

Well...My success with the rear window gasket did NOT translate to the front   yes there were (almost) tears, and lots of colourful language, and in the end of course I trashed the gasket and spent 4 hours cleaning sealant from every surface and body part know to man, fun times...

Now, I totally respect other members' opinion and expertise, and if sealant in the channel (at the pinch weld) works/worked for you, great, but I will NOT be using sealant again on the front, that is for sure!  I used it on the back and it worked a treat, but for some reason the sealant on the front created too much of a barrier and the seal would not pull in with the rope.  Of course a lot gooped out, but even after I pulled it all out there was still tons of sealant in the channel.  I used one full tube of 3M Glazing and Bedding compound as I did on the rear.  So new seal ordered, and open to suggestions.

I see reference to greasing the outer edge of the seal (where it would sit in the channel in the car) to ease install.  Any tips on this?

I must say that getting the unit out was a breeze, no breaks.  I just followed my method I used in the back,  take your time, and slowly pull/cut away the seal in strips.  Essentially then you lift the window free and clear with absolutely no stress caused by the seal still left in the body.  i do not advocate the "push from inside approach", the differential stress is just too much in my opinion and I would venture this is where most of the breaks occur.  Then you just rip out whatever is left of the seal after you lift the glass out free of any attached gasket.  Chop-chop really

So again I am open to a "hybrid" approach, and will probably make up my own as I go along.  Just thought I'd get some sympathy this morning after "failure to launch"

Cheers

[polymathman]

Hey Daniel!

Good to hear from you, and let me say I have enjoyed many of your posts.

In all honesty, I really didn't know what I was doing when I did my first install. My uncle, who has YEARS of experience in Boston working on exotic cars told me simply to figure out how and why things work - it was a top of the line design. Upon examination, we realized that it really didn't need any sealant, but some, carefully placed, wouldn't hurt.

The things I made sure of were the surface of the metal should be clean and smooth and the gasket should be clean and flexible. The gasket comes with a powder coating used in manufacturing and I soaked the whole thing in warm water with some detergent then went over each groove looking for irregularities.

I then did the first practice install, using the new gasket and the old cracked windshield, and was easily able to do it by myself. I learned that I needed to get the centering correct before I started (used tape to mark), silicone would help things slide. I had to keep in it for a while I waited for the new glass to arrive. Removal was easy, and it was where I started the video.

I saw that it was necessary to use the string on the bottom channel to stop the "ruffling". The rest is in the video.

A bit of sealant was only applied into the outer edge of the seal after assembly to act as a first line of defense. I used masking tape around the edge to stop the mess, and solvent to clean up. Then I went around the glass-to-seal area with the tip just under the rubber, then kinda pressed the seal down to squeeze out the excess, with special attention to the bottom corners. Waited until it set up, ran a razor around the edge (glass) and scraped off excess. Had most of a tube left over. I liked the MB sealant, and it wasn't all that expensive.

It's been a while, and I haven't had any problems even with pressure washers.

Ken

[daantjie]

Thanks Ken!

What role do you think ambient temps play in the the whole process?  I know some folks said that you need hotter temps for the sealant to flow better, but that was not the issue for me.  It flowed all OVER the place!

Thinking that if the seal is warmer it will go smoother overall?  When I did the rear seal it was close to 30C ambient here in Vancouver.  Now temps are closer to half that, hmmm...Maybe I am going too far into the woods with this line of thinking?
Cheers

[daantjie]

Further to this, I actually read the pertinent section of the service manual last night, and in there it does not mention sealant in the body cavity, just on the outer glass between the glass and seal after install.
It also mentions "2 ropes", but I cannot see why you would want 2 separate ropes for pulling.  Also mentions "acid free" grease to be used on the seal to ease the install.  I know the manual is not always the gospel and that there are many ways to skin a cat, but I am going to try it "the Benz service manual way" and see what happens...

But now reading it again, it DOES say to put sealant "between spot flange and sealing frame", as step 13, but this is after you put the unit back in, WTF?  So are you then supposed to go inside the car and somehow get sealant under the lip.  That would obviously A) be very hard, and B) lead to a huge mess.  Ugh, just for once I wished some things did not get lost in translation.  Here is the section pasted from the manual:

[Diesel 617]

I think what they mean by two ropes (and this is what I did); is to have two ends you can pull from. The trick it to ensure that the corners seat properly, as they have a tendency to want to 'float' and create a gap. Applying even and correct pressure may ease the install.

[s class]

I always use a good healthy dose of that 3M bedding and sealing compound between the seal and the pinchweld. 

If it cheers you up, I find the 116 front screen to be one of the more difficult ones to do (compared to 111, 108, 123 etc). 

I have recently discovered a trick though, that I route the pulling cord such that the ends are at the top of the screen, not the bottom, and then I start the pulling operation and seat the TOP edge first.  THis is the opposite of what is conventionally done.  It does mean though that you cannot do it alone, you must have a helper to support the weight of the glass, otherwise it wants to slide down and off the top pinchweld. 

[wbrian63]

But now reading it again, it DOES say to put sealant "between spot flange and sealing frame", as step 13, but this is after you put the unit back in, WTF?  So are you then supposed to go inside the car and somehow get sealant under the lip.  That would obviously A) be very hard, and B) lead to a huge mess.  Ugh, just for once I wished some things did not get lost in translation.  Here is the section pasted from the manual:

I think they intend the sealant to go on the outside. If you put it on the inside, you of course have the horrible mess, plus it allows water to work under the gasket all the way up to the sealant.
Working it in under the outer lip of the gasket will keep everything behind the sealing line dry, which is a best-case scenario, in my opinion.

[daantjie]

Thanks guys, I figured as much with regards to the sealant.  It seems like it is more of a touch up as needed after the unit has been installed.  Looks like lower corners are the main spots you really want to hit with the sealant due to pooling of water in this area.

Ryan, thanks for the tips as well.  As I am doing this solo I will have to start at the bottom.  Hoping that if I get it to sit up on the weld at the bottom then it should work it's way to seating at the top as well.  Also I can push from the outside while pulling the rope via the driver and passenger windows so I am hoping I can coax the thing into position this way.

I will update this thread once i (hopefully) have this damned thing in!

Cheers

[marku]

You do really need help just to lean on the screen from outside. It sits quite easily on the bottom metal and I was surprised how quick and easy it was. Sit in the middle with both ends at the bottom and in the middle and pull alternately working round. Bit difficult on the sides and top corners as I think the new seals don't quite fit the contours. There was a very good video of it being done posted some time ago. Had I seen it would have made it much easier. I intend having another go as not happy with finished result. Think that the previous owner pulled the trim out before removing the screen and slightly bent it.

[daantjie]

SUCCESS

Did it from the bottom to the top and it was of course not a cake walk but quite pleased with the end result.

I used some pastic wedges to prop it up at the bottom and this help to get the bottom lip over the flange.  By yourself I do not see any other way honestly as the unit wants to constantly slide down if you pull from the top as Ryan has confirmed as well.

Again this is a much easier job with a capable 2nd set of hands but I am living proof that it can be done solo

[marku]

You can congratulate yourself quite an achievement. Not only keeping the pressure on the outside but just handling and getting it to sit right from the beginning. Any problems with the trim? I couldn't get it right and I will have to do it again sometime. As I said before the previous owner for some reason pulled it out and I think must have distorted it so it wont sit. Is it the new seal you have where the trim goes under the rubber? I thought it really difficult until I saw the video of a professional doing it.

[daantjie]

You can congratulate yourself quite an achievement. Not only keeping the pressure on the outside but just handling and getting it to sit right from the beginning. Any problems with the trim? I couldn't get it right and I will have to do it again sometime. As I said before the previous owner for some reason pulled it out and I think must have distorted it so it wont sit. Is it the new seal you have where the trim goes under the rubber? I thought it really difficult until I saw the video of a professional doing it.

Thanks!  I think the key for me was also that I spread the job out over a few weeks, ha-ha!  For me the trick to getting the trim nice and locked into the channel was a light smear of Permatex Dialectric Grease.  I found it very hard to press the trim into the channel without some lube to make it slide in.  I was a bit worried that the lube will make it want to pop out easier once you compress it in the frame, but seemed to have stayed put.

For sure your trim must be surgically clean before you start, and yes I made sure the trim was nice and straight.  The top 2 sections have a curve of course to follow the contour of the window at the top, so best to place them on a flat surface and eyeball them both to ensure that you are getting a nice, even and smooth arc.  If your trim is bent you will have a helluva time getting it in and then to have it sit right on the car.  As with any job prep and planning are key, especially if you are doing this alone as the chances of things going pear shaped are a lot bigger when doing it solo

As others have mentioned lining up the unit is absolutely critical.  You MUST have the unit perfectly centered before you start pulling the rope in. It is very tricky to measure the window to get the mid point as it's all curved, but I managed to do it with a long spirit level.  I marked top and bottom mid points of the seal with a white paint marker, then marked the center on the car and lined these up. I also used the silicone grease on the outer edge of the seal, not too much but just a light coating.  That also makes the seal want to go in easier.

Yes I got a new seal from the Classic Centre with the lip over the trim, and the way Ken a.k.a "polymathman" shows in the video is absolutely the only way to this.

The top corners on the driver side is not perfect, but good enough for rock n roll for me.

Other than that, a lot of patience, as you really pull it in inch by inch, alternating from side to side.  The rope got very tight to pull on the top, especially around the corners, but I think most people have found this, i think it is just the nature of the beast.  Wear heavy gloves as the nylon greased rope makes a rope burn almost a certainty!  Steady pressure from outside will make it easier of course.  I was worried that the window will crack with the stress of the rope, but at that point you pretty much have to go balls to the wall and just keep pulling the rope, no going back really

Cheers

[ptashek]

Pics, or it didn't happen
Congrats on finishing, probably, the worst job on these cars.

[marku]

Well I believe you photos or not. I had the advantage of a willing wife who stood on a step ladder to lean on the centre of the screen while I pulled the cord inside. Hadn't thought about accurately lining up the screen in the centre. Did it visually and that may have contributed to the misalignment of the trim. Any way I do intend another go but at the moment about to replace the rear screen seal and the boot so plenty to do.

[daantjie]

TA-DAH!