Rear glass water leak

[cossie]

The rear glass started to leak a bit of water (like 3-5 drops) after a carwash. It drips to the edge of the headliner and falls on top of the rear seat beside the headrest. From the outside, the top edge of the rubber seal is soft (can be easily lifted by a finger), no cracks,, no body rust, inside of the seal is clean but there is a portion (like an inch or so) that is not really flush to the body. Since I don't want to risk damaging the glass by removing and resealing the whole thing, is it ok to use a bit of beading sealant to close the gap of the top edge of the seal? What is the best one to use? Any other recommendation for possible fix is appreciated.

Thanks.

 

[nocfn]

If this is a E500E and you care about selling the car in the future, remove the glass and replace the seal. You can purchase everything except for the center cover so RETAIN THAT PIECE. I just recently replaced my backglass and seal with new. If you have a helper and professional glass suction grips this should be a walk in the park. Glass on a stable stand padded, and the curves are UP to catch the water while you remove the old seal and clean the frame channel for reinstall. You may also need new rivets for the other clips at the bottom for the covering seal.

 

[Ertech]

you can also use urethane calking from the inside with a long spout after you remove the rest pillar trim,.

 

[cossie]

Thank you again nocfn. I'm not in the US so parts may be difficult to source especially the glass, if it breaks. Since it's not a major leak I'll try to patch things up.

@Ertech do you mean lifting the rubber seal lip and injecting calking inside? Do I fill it up or just enough to seal the edge? Do I need to remove the pillar trim? There is a small gap to access the rubber lip.

 

[Ertech]

I think the rubber lip is to guide the water not seal the glass. The glass is glued with eurethane calking like any modern car
You remove the inside trim and use the calking .
Something like this

 

[gsxr]

That was my understanding as well... the glass is attached/sealed with urethane, any water leak is related to this urethane adhesive, or a hole in the sheet metal from rust/corrosion.

The trim and rubber seal just direct water away from the channel around the glass.

 

[nocfn]

This is true, urethane holds the glass to the chassis and the rubber seals the gaps from the indented frame. When the frame/seal came off mine, there was a lot of trapped dirt under there, and a leak formed top right, about 10-20 cm from right corner inward. The urethane bead was thinner there than other areas. The rubber also shrinks some over time and weather and the clock march on. I had some cracking of the glass which precipitated my swap, upper left - unrelated to the leaking so I replaced it.

EDIT MB makes a glass sealant that really doesn't get rock solid hard (in my owner's thread I think) I used on my back glass for the 91 560SEC. It had a flat tip applicator, and I easily slipped it under the lip of the seal once the entire unit was fitted. It was quite simple to install a consistent bead under the lip to fill any irregularity under the sealing surface and the channel's edge flush with the body.

 

[Ertech]

Maybe I am wrong but I think the non hardening one if for windshields that are not glued like old cars that have a rubber seal to keep water out of the frame

 

[nocfn]

Originally they used a sealing cord on the frame, that dried out, shrunk and cracked and allowed water to enter under the floating seal that had shrunk over the years. That cord is not available, nor would I want it. The product used was searched by MB as an option. It is for newer cars. I am no expert, just reflecting on my personal experience. Improvements made over failures and that is what MB came up with to use instead, on both sides of the glass. YMMV

 

[daantjie]

3M Auto Bedding and Glazing Compound is great stuff.

 

[cossie]

This is true, urethane holds the glass to the chassis and the rubber seals the gaps from the indented frame. When the frame/seal came off mine, there was a lot of trapped dirt under there, and a leak formed top right, about 10-20 cm from right corner inward. The urethane bead was thinner there than other areas. The rubber also shrinks some over time and weather and the clock march on. I had some cracking of the glass which precipitated my swap, upper left - unrelated to the leaking so I replaced it.

EDIT MB makes a glass sealant that really doesn't get rock solid hard (in my owner's thread I think) I used on my back glass for the 91 560SEC. It had a flat tip applicator, and I easily slipped it under the lip of the seal once the entire unit was fitted. It was quite simple to install a consistent bead under the lip to fill any irregularity under the sealing surface and the channel's edge flush with the body.

My leak seems to be in the exact spot as yours, around 20cm inward from the upper right corner, just barely missing the headrest when it drips. That being said, can I just use the sealant under the lip similar to what you did with your 560SEC to drive water away from the urethane adhesive? If the lip is sealed, then water won't reach the glass adhesive part.

 

[nocfn]

I think you can try that with any type of sealant for such purposes. If I may suggest, try a bit further towards the center, bringing the bead around the corner just a bit. I just know on my car and experience, there was quite a bit of dirt in there not accessible until after the framed seal was removed and there is a risk of cracking your glass. You are just going to have to do what your wallet allows, and acceptance that you may run the risk of trapping moisture and you could foster a corrosion over the years. Just be smart about it and I wish you well. E500E specific glass is around 1500 installed here for me at the AMG body shop at the dealer.

 

[cossie]

Sorry if I was not clear on the issue, the lip of the rubber does not sit on the body. This is where the water enters... so far no rust inside. I just noticed the few drops on top of the backrest after a carwash, maybe caused by the high pressure of the water hose. Can this be pushed back to original position? .

 

[nocfn]

worth a shot, use a blunt plastic tool and use some sort of lubrication like, sadly...water. That is obviously an issue as it does not work as intended. good luck

 

[cossie]

Thank you @nocfn for the tip. I massaged the rubber seal with a flat plastic pry tool with some water and it worked, it took awhile though. The rubber lip is now flush to the frame. I also checked the upper pinchweld by lifting the headliner and there is no sign of rust. The leak appears to be coming from the urethane adhesive.

Question now is, since the seal is now flush, is it suppose to stop water from entering the channel? Meaning I don't need to re-seal the glass since water will no longer ingress. Also, is it advisable to spray cavity wax on the exterior pinchweld (inside the seal) of the top channel for rust prevention?

Thanks again.

 

[nehuge]

Agree on the 3M glazing and bedding compound. It stays pliable forever, no crumbly stuff, etc. It is messy though, so mineral spirits or acetone is great for cleanup. I used it to seal my wagon's rear side windows after I took them out and got new rubber seals for them. The MB writeup specifically stated to add their version of the sealant between the body and the rubber seal, and also between the rubber seal and the glass. The old MB stuff was crumbly and I had the famous "fogged up windows" in the morning and it was due to these seals. The point I'm getting at with the wagon is that I'm going to apply the same concept to my sedan, and here's why:

 

[Kridre]

I always learn something new on this forum. Now I know why my 400E was rusted out around the rear glass! When I had my glass replaced 2 times, no one even knew to use the glass compound on the rubber seal... It is clearly stated in the FSM to use it. Now, when I get my glass installed again, I need to make sure that they do it like this. Otherwise, it will rust again.

 

[nehuge]

I always learn something new on this forum. Now I know why my 400E was rusted out around the rear glass! When I had my glass replaced 2 times, no one even knew to use the glass compound on the rubber seal... It is clearly stated in the FSM to use it. Now, when I get my glass installed again, I need to make sure that they do it like this. Otherwise, it will rust again.

View attachment 177141

Absolutely correct! The FSM calls it out.