Rubber trunk seal is (probably) leaking
 

About 2 years ago, my original 25 year old trunk seal was leaking so I started looking around for a new one. I always tell people "avoid buying stuff made in China where feasible", and I say that because I know sometimes it's hard to avoid them.

Case in point, a genuine Mercedes seal was about $240, a Uro brand from China was $39. The disparity was just too great and the Uro had some decent reviews.

That was 2 years ago, if that. Now my trunk seal is leaking again.

It's not coming UNDER the seal from what I can see, but OVER the seal just from what I can see. When I first got the new seal I actually had trouble closing the trunk because the new seal was so thick. I really had to slam the trunk to close it and at the time I thought "Wow, my old one must have been really compressed over the years". With this new one, I don't have to slam the trunk closed anymore, it's been compressed some of course but it doesn't seem to be compressed too much but the leak is coming in from somewhere.

I supsect the seal. It's possible the trunk lid stops are partially to blame. Someone said that if those are dryrotted away (mine were but I built them back up with some silicone), then the trunk lid goes down too far to shut which compresses the seals too much.

Any thoughts? There's nothing unusual regarding debris or leaves clogging the channel.

Thanks,

1991 300d, 219k

That's interesting. My trunk seal looks terrible and seems to not leak - I'm pretty sure its original. I just ordered a new URO one mainly because mine "looks" bad. We'll see - I'm interested because on my other 87 and my 88 both were replaced with URO seals and they kept it dry.

Another source of water
 

Another source could be coming in from the tail lights (though I checked those areas) and the moisture and sheer wetness that you see on the underside of the trunk lid could be from that moisture basically trying to evaporate. It goes up and hangs out on the underside of a trunk lid.

However in my case, I'm seeing the water just on the left side, not the right of the trunk. I know that it's not coming in through the antenna either. I replaced that seal a few years ago and it's not leaking.

Trunks seals are more for wind blown water than rain. Pretty much the only way to locate is to put someone in the trunk with a flash light and mist with water. Don't use a high pressure spray as this can get under a good seal.

PS, make sure the person outside the car has keys. . . .

I often buy OEM
 

I often buy OEM parts, but when the difference is about 8x the price for OEM, you're saying you go with the originals, huh?

You are doing fine. A generic trunk gasket is OK to use.

Try to rejuvenate the existing seal with a bit of aerospace 303 - it might help to spring back over compressed rubber - and importantly I find when cleaning something properly the chances of actually finding damage increases

(If I could get away with it I'd like to wash a car at least twice before buying it - that way I'd actually be able to see the wood for the trees so to speak and have a better idea of what I'm about to get!)

No glue or caulking used when installing new gasket
 

Incidentally, I didn't use any glue or caulking when I put the new rubber gasket in and I don't think it is supposed to be installed with any. Does anyone know for sure?

I'm pretty sure it should be installed with sealant - 3m makes good quality weatherstrip adhesive.

Coincidentally, I've had the exact same issue. Unfortunately I didn't catch it until I started getting some rust in the rear fenders just behind the wheel arch. I POR-15'd the entire trunk bottom due to some other rust, but didn't get into the crevice where the wheel arch meets the fender. I just got a welder to do the repairs, but need a ton of practice first. In the meantime until I can afford OEM seals, I added some universal automotive weatherstripping (From the big blue store) to the bottom edge of the trunk lid. It seems to have helped make a good seal, in that it's more difficult to shut the trunk now, but I haven't had the car in the rain to see if there's any more water ingress.

I'd strongly suggest you rustproof the trunk floors and side wells before you run into more problems, like I did. A bit more paint would have saved me a ton of work and money for paint blending.

Pretty sure the OE is glued in at the factory on this seal.

a generic roll of trunk seal can be used here, The same ones used by classic car rebuilders. Usually they are of pretty decent quality.

The issue with most older model mercedes rubber even when bought new is that the rubber has already aged.