W164 tail light seals question

[Albi AD]

Hi everyone,
After searching a lot in forums i failed to find detailed information on sealing the new tail light seals on my w164. I had my tail light seals replaced in January 2021 with OEM parts from the dealer. A local mechanic installed and applied silicone but 3 months later i discovered that the right seal (where the SAM is located) had some rain drops. From my search it results that the adhesive in the seal should be installed on the body of the car and not in the tail light. Now my questions are:
What have you used to seal the tail lights? Silicone? Is silicone necessary to apply on the side of the seal that already has adhesive? After installing the seal to the body of the car should I apply silicone in order to seal the part where the tail light attaches to the seal? Any additional information is appreciated.
Locally i could find sealant for the windshield and I am having difficulties finding other sealing products. Is it okay to be used in this case?
Thank you.
Edit

 

[Uncle Benz]

Silicone usually works. It isn’t uncommon for the rear quarter window to leak from the white plastic locating dowel, so maybe check for that too

 

[Albi AD]

Silicone usually works. It isn’t uncommon for the rear quarter window to leak from the white plastic locating dowel, so maybe check for that too

Thank you. Should I apply silicone on both sides of the tail light seal or only on the side which does not have adhesive?

 

[Uncle Benz]

If the foam seal is still well attached to the lamp there is usually no need to remove it and reseal. Do look carefully though, and gently pull at it, check it is still attached and in good condition. If it looks like it is rotting, replacement is a good idea

 

[Albi AD]

If the foam seal is still well attached to the lamp there is usually no need to remove it and reseal. Do look carefully though, and gently pull at it, check it is still attached and in good condition. If it looks like it is rotting, replacement is a good idea

I bought another OEM seal and thats what I plan on fitting this weekend so I am going to remove the seal that was installed in January because it got damaged when the mechanic tried to remove it last weekend and so I ordered a new seal from the dealer.

 

[Uncle Benz]

Do stick your head in the hole and take a look up. If the window is leaking there is often a dried trail that gives it away. Mercedes knew about this being a problem area. They moved the rear SAM to under the back seat around 2010. Sadly the early cables aren’t long enough for that, but it is possible to bring the rear SAM into the area just behind the flap, next to the fuse box and still get the flap back in place. I run mine like this. If a leak ever occurs again the SAM is out of danger.

 

[Albi AD]

Do stick your head in the hole and take a look up. If the window is leaking there is often a dried trail that gives it away. Mercedes knew about this being a problem area. They moved the rear SAM to under the back seat around 2010. Sadly the early cables aren’t long enough for that, but it is possible to bring the rear SAM into the area just behind the flap, next to the fuse box and still get the flap back in place. I run mine like this. If a leak ever occurs again the SAM is out of danger.

That is fantastic information. If possible can you please send a photo of how you have placed the rear SAM?

 

[Richard Moakes]

Just recently replaced these seals on my w164, I applied the seal to the vehicle using the sticky side, and then offered up the light cluster and tightened up the fixings. Pay attention to the oval side seal, that’s where mine was leaking.

 

[Albi AD]

Just recently replaced these seals on my w164, I applied the seal to the vehicle using the sticky side, and then offered up the light cluster and tightened up the fixings. Pay attention to the oval side seal, that’s where mine was leaking.

So you did not use any additional sealant only the one in the seal ifself? Mine was leaking in the red mark in the photo.

 

[Richard Moakes]

So you did not use any additional sealant only the one in the seal ifself? Mine was leaking in the red mark in the photo.

No additional sealant, my leak was around the side where there is a single fixing.

I read they came from the factory with the seal incorrectly fitted with the sticky side to the light cluster. Made more sense to me to stick it to the bodywork and let the ridges on the light cluster press into the foam to make a seal.

 

[Albi AD]

Thank you for the response. Yes I also read in forums that the seals were installed incorrectly from the factory so I am going to install as per your suggestions and also add some silicone for double protection.