Installing back glass (with defroster), help needed - PeachParts Mercedes-Benz Forum

funola · #1 06-11-2013, 04:05 PM

I have decided to replace the back glass myself (finally found one with a good defroster). I was going to have Safelite do it but changed my mind after talking to the shop that was going to do it and was told the correct way is to rope in the glass first, then install the aluminum ornamental moldings.

Safelite (different shop back then) did a windshield for me a few years ago and the installer had a hell of a time (doing it the same way, which I found out later was incorrect). He was sweating bricks, couldn't get the aluminum moldings in right, pulled them off and tried again, left the job and came back a few hours later and kinda forced them in. The windshield leaked which they used sealants to fix. So I don't want them to F this one up and decided to do it myself.

I have a question regarding the Mercedes sealing compound application (step 16 below), which implies it is done after the glass has been roped it (between glass and rubber and rubber and window frame). Is that correct? Wouldn't it be easier to apply the sealant between glass and rubber before roping it in?

cooljjay · #2 06-11-2013, 05:31 PM

When I installed a new gasket in my last car, I didn't use any sealant.....I simply cut the old seal away from the glass....lifted the glass out, removed the chrome from the old seal....placed new seal around windshield....inserted the chrome....then I put rope in the channel of the seal that goes onto the pinch weld.....then I pulled the rope out starting at the top....the bottom lip didn't get pulled in, in the center so I use a bent screw driver to pull it in....never used sealant....and never had any leaks.....I had a company do my front windshield, because it need new glass and they did the same safellite did on yours....hammered the trim in afterwards....totally jacked it up....but no leaks...but my car got impounded and some how they tore the rubber gasket....now I have to redo it again

rscurtis · #3 06-11-2013, 05:35 PM

Stories like this are why I had the windshield on my signature car replaced by MB of Huntington on LI. It was pricey, but done right the first time.

cooljjay · #4 06-11-2013, 06:01 PM

Quote:

Originally Posted by rscurtis

Stories like this are why I had the windshield on my signature car replaced by MB of Huntington on LI. It was pricey, but done right the first time.

When I had safelite install the windshield in my other Benz a few years ago, the tech did an amazing job....it was done correct and perfect....then I called to have it done on this one and they said they no longer do windshield's on these cars...I even had a rock fly up and star the windshield, they fixed it for free! So the only company I could find was a cheap Chinese outfit....and they destroyed it....I was missing the seal and chrome....and he didn't even bring all the chrome with him....I was in a hurry to have it done, so I just said what ever...

Diesel911 · #5 06-11-2013, 10:21 PM

I did not replace My Rear Window but I took it out to repair the Rust hoes at the bottom corner.
Since I found a whole bunch of busted Glass bits under ther rear Deck and Rear Seat I assume the original Window was butsted and from the looks of the Rear Window it was a Junkyard replacment.
I reused the Rubber Seal as it was OK.

I used the 2 types of Suction Cups to help move the Window around and those Blue Plastic Harbor Freight Door Panel Tools (I have 2 sets) to pry with.

I did not use and sort of Rope or Cord to pull or a Window Remover Tool to cut the Seal. But in My case the the Rubber was not stuck on with Sealant.

Put a Blanket or somethng on the top of the Trunk so that the Glass has something soft to rest on.

rs899 · #6 06-12-2013, 07:36 AM

I personally would not use any sealing compound unless it leaked. Then I would use clear silicone seal between glass and seal. 3M makes a bedding compond similar to the MB stuff that can probably be squeezed in under the rubber later (with someone helping with a putty knife).

Make sure you get it centered before you start and use a lot of lube. It's a bit off-putting to stretch the rubber over that thin glass - just do it a bit at a time and use duct tape to keep it on. Have fun!

KAdams4458 · #7 06-12-2013, 01:12 PM

I used the 3M bedding compound on mine. It's not too difficult to do, and it is what the FSM says to do, so I did it. Getting the tip under the rubber to start is a bit of a pain, but once you get it in there, dragging it around while gunning in the goo isn't too difficult. You can use a razor to remove excess compound that oozes out on the glass, and a credit card works reasonable well on the painted portions, then you just follow up with some mineral spirits and a rag to eliminate the remeaining residue.

funola · #8 06-12-2013, 01:20 PM

Kadams, thanks! Can you describe the rope in process? What did you use for lube on the rope and rubber?

KAdams4458 · #9 06-12-2013, 02:56 PM

Two pieces of clothes line overlapping at the top and bottom of the glass, right in the middle. Lube can be eithe talc powder, or something like dishwasher rinse aid mixed in water. I basically did exactly what the the FSM says to do. Rope in the bottom edge first, or the glass just follows gravity downward when you rope the top.

Don't be discouraged if you screw up the first few attempts and have to start over. It takes an attempt or two to really get the hang of it.

NC-Diesel · #10 06-12-2013, 09:07 PM

I just did the front and back windows in my 1981. I bought the mercedes sealing compound. It was expensive but works well. It's non hardening so the next guy replacing it won't have to get out an angle grinder and wire wheel like I had to do after somebody used 3M on my 1978!

PackerEdgerton · #11 06-13-2013, 09:46 AM

Hi Funola,

I had the rear windshield professionally done.

Here's what he did:

1) clean off frame and windshield.
2) Put gasket on windshield (it was sitting on a cradle). He used windex as a lubricant to help him.
3) Put trim on gasket (I helped him)
4) Clean off frame (again) and apply a kind of black primer across the entire frame. Let dry
5) Put the rope on the windshield.
6) picked up the windshield with the suction cups, and place in the frame
7) With me apply force from outside, and him from inside (he had the suction cups on inside of car), he pulled the windshield in and then slowly pulled the rope out, ensuring that the gasket was properly 'popping' out behind the frame on the inside of the car.
8) He used masking tape around the outside of the windshield to define a 'border' around the windshield.
9) He used 3M windshield sealant. Put it in a caulking gun, stuck the tip UNDER the outside of the windshield gasket and went all the way around the windshield.
10) He smoothed the sealant (which was now UNDER the gasket and squished out the edge) with a rubber gloved hand and some windex.
11) Let dry for a few minutes, then peeled away the masking tape.

DONE

I hope that helps.

Packman

funola · #12 06-13-2013, 03:14 PM

Thanks for the detailed steps! I do have a few questions.

1. Where and how hard were you pressing on the glass?

2. Do you think he could have done it alone, without your help?

3. What kind of 3M sealant did he use? Was it a non drying putty?

4. Sealant was not applied between glass and the rubber lip?

Quote:

Originally Posted by PackerEdgerton

Hi Funola,

I had the rear windshield professionally done.

Here's what he did:

1) clean off frame and windshield.
2) Put gasket on windshield (it was sitting on a cradle). He used windex as a lubricant to help him.
3) Put trim on gasket (I helped him)
4) Clean off frame (again) and apply a kind of black primer across the entire frame. Let dry
5) Put the rope on the windshield.
6) picked up the windshield with the suction cups, and place in the frame
7) With me apply force from outside, and him from inside (he had the suction cups on inside of car), he pulled the windshield in and then slowly pulled the rope out, ensuring that the gasket was properly 'popping' out behind the frame on the inside of the car.
8) He used masking tape around the outside of the windshield to define a 'border' around the windshield.
9) He used 3M windshield sealant. Put it in a caulking gun, stuck the tip UNDER the outside of the windshield gasket and went all the way around the windshield.
10) He smoothed the sealant (which was now UNDER the gasket and squished out the edge) with a rubber gloved hand and some windex.
11) Let dry for a few minutes, then peeled away the masking tape.

DONE

I hope that helps.

Packman

rs899 · #13 06-14-2013, 08:01 AM

You need someone to push moderately hard on the glass to keep it stable and from popping out as you pull the strings. They also need to apply pressure to your command at the spot you are working on. I doubt it can be done alone, certainly not the first one. I have probably done 6 or 8 of these , and I don't think I have the skill do do one alone (it would take the rubber cups pulling from inside and you would need to pull the string with your teeth )

It is good that your old one is still usable, if you screw up. The first one seems intimidating, but the learning curve is steep. Even within the first attempt, it gets easier. Just do it!

Squiggle Dog · #14 06-14-2013, 11:05 AM

I installed the front and rear windshields in a W111 sedan by myself. I first tried ÜRO and Febi seals. Both were junk! I could not get the assembly to fit no matter how hard I tried. Then I bought ones from the dealer. The OEM rubber was softer and thinner than the ÜRO and Febi ones. Guess what? The assembly popped in and seated properly on the FIRST TRY! The trim didn't even try to pop out, rather it got sucked in tight as the glass seated. The difference was night and day.

Besides the aftermarket rubber being too thick and hard, the upper corners weren't even molded and the trim groove didn't have a locking lip to hold the trim in place. All the aftermarket rubber did was pop out of shape and the trim wouldn't stay in, while the OEM rubber fit like a glove and popped right in while sucking in the trim tightly.

If you don't use the Mercedes sealing compound, you can usually source 3M Bedding & Glazing Compound 08509 (non-hardening black--NOT hardening 3M Windo-Weld Super Fast Urethane 08609--that's for glue-on gaskets, but might be useful for filling in large gaps or broken portions of the seal) at an auto parts or auto body supply store.

However, if you don't do the job on a summer day or in a heated building, chances are the tube will blow out partway through the job and you'll have to get another one. Removing the contents of the tube and putting them in metal applicator of some sort might prevent dealing with bursting tubes, especially if you can get a heated applicator tool.

Since it is non-hardening, I believe you can apply it between the seal and glass before installing and wipe off the excess with a plastic scraper and glass cleaner. As an additional measure, you can use a plastic prybar and insert the tip of the sealant tube under the seal to body area and fill this area with sealant, though the plumber's putty should be enough.

Squiggle Dog · #15 06-14-2013, 11:13 AM

In a previous W116 300SD I owned, I got a good deal on a new Chinese Fuyao Glass Industry windshield and a new Thai Mygrant Glass Company (DNK) seal; $30 for both from a glass shop that was liquidating its inventory.

I had a reputable glass shop install them (recommended to me by the local independent Mercedes repair shop), but they leaked really badly. I had them back twice and each time they squirted more sealer into the seal, but it still leaked (the installers said in their whole careers that this is the most difficult windshield any of them has ever done, and they kept accidentally stabbing each other with their picks). They also left chunks of the old sealant with parts of the old seal still on the lip! No wonder they couldn't get the glass to seat. That Chinese glass also chipped very easily, and every day I would have a new chip or star in it.

I went to the Mercedes-Benz dealer and ordered the $140 windshield seal. Then I had Safelite install a new PPG windshield for $240 (57% off sale). Of course, the PPG glass had a "Made in China" sticker on it.

After 2 hours my car was ready, but a couple days later it rained and the windshield was leaking worse than the previous one! Though it was not installed as poorly as the other glass shop did, it still looked like the windshield and gasket were not set in all the way. It looked like the windshield was floating on the body, and the upper corners were open so I could look inside.

Of course, the seal got all torn up from installation, and was already cracked. In the center of the roof the seal fell in because of the gap between the seal and the body. And I could pull the lower corners of the seal away because apparently there wasn't any sealant in there.

I questioned Safelite if they left old sealant and parts of rubber on the pinch welds, but the installers said, "It doesn't matter, it just means we have to use less sealant". I went back about five times, and each time they kept filling it with more sealant and complaining about how much it was costing them. They never could get it to not leak, so I bought some bedding compound and sealed it myself. I was too nice of a guy back then.