Water in Trunk!!!
I have searched the forum and seen some of the other posts, but I don't seem to have the same problems and can't seem to find the culprit of my leak.
It is only on the left side, and the lining is wet in the picture below in the red circle:
When I lift the trunk floor to access the spare tire, it is also wet in the areas below, and the water is collecting in the little styrofoam compartment (see red arrow)...
I can't tell where it is coming in from. I have checked the little plastic "rivets" and they seem in good shape. The weather stripping looks good and is fairly clean.
I removed the trunk license plate trim piece from the trunk lid and cleaned that out, and I trimmed some of the foam in the center drain to allow water to drain between the plastic license plate trim piece and the trunk lid (I actually thought this was the culprit, but I'm still having water ingress)... I did not completely remove the foam, and the foam seems to remain wet after a rain, but I do believe there is plenty of space for water to drain there (like 1/4 inch on each side of the foam. Maybe I should completely remove the foam?
Does anyone have any other specific suggestions of why the water would only be on the left side in that area? Maybe the gasket between the tail light, but I would assume this was cause water to collect lower in the spare tire area?
Any suggestions would be appreciated.
Thanks
Lee
2004 W211 E320





Water flows off the rear window, the travels *under* the plastic trim on the side of the trunk lid seal on top of the rear quarter panel. The plastic trim guides the water along the side of the tail light and dumps that water just about the spot where the trunk lid seal makes the horizontal to vertical transition. Mine was clogged with debris so water would stand in it next to the trunk seal then wick underneath the trunk seal and into the car. Over the years it rusted enough that there was a small channel for the water to flow through. Cleaned the plastic guide (and cut it back a bit) removed rust and resealed the trunk lid seal and no issues since then. Mind you, it is difficult to follow the plastic guide and see the end of it as it is right about even with the bumper cover.
I have removed the interior trunk trim pieces, and got in the trunk with a flash light while my son used the garden hose to soak the rear of the car. I didn't see any leaks around the trunk seal. I removed the left tail light assembly and found that one of the stud bolts for the light assembly was not seated into the plastic of the light assembly (it was basically spinning like it was stripped, but once I remove the tail light, and held the stud from the outside, I could remote the inside nut, and the screwed the bolt back into the plastic on the light assembly (it was like a self tapping wood screw), and it seated pretty well. I'm not sure how that happened, but it obviously wasn't holding the light assembly properly. I also noticed that another one of the studs had been previously repaired (looked like JB weld or some other plastic/epoxy) and the epoxy was failing, and I could move the stud. Also, the inside of the tail light was holding some water (not sure how I didn't notice this before).
I now believe that water was entering the tail light assembly due to the problems with the mounting bolts, and once the light assembly was full of water, then it was flowing into the trunk... I re-epoxied the broken bolt, and put the light assembly back in, but I haven't water tested yet as I don't believe this is a long term solution. I also ordered a used tail light assembly online (not yet received), and assuming it is in good shape, I will swap it for my dodgy one and hope this solves my problem.
Thanks again for all the advice. I'll report back if I find anything else.
Lee
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I have replaced the tail light with a used one (one of the bolts on the original one one broken, and water was leaking around the original tail light), but I am still getting water coming on around the tail light. See the picture below taken from inside the trunk and you can clearly see water coming in at the red arrows:
I assumed that the bolt just above the water leak would need to be tightened, but it is already pretty tight and I am afraid I will break something if I go any tighter.
I have ordered a new foam gasket (211-826-03-91), and hopefully that will fix it.
Lee
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Just to close this out for anyone with a similar problem, I first replaced the tail light (one of the studs was broken on mine) but still had leaks around the tail light; then I replaced the foam gasket (211-826-03-91) between the tail light and body, and this solved this leak. I believe the foam gasket was actually the issue, and the broken stud in the tail light assembly was just something that needed fixing (or maybe combination of the two). If you have any suspicion that the leak is coming from the tail light assembly, I would replace the foam gasket.
Also, once the gasket was replaced, I tried to dry everything in the trunk and do a hose test. At first I got no water, but after a few hours of sitting, I continued to see small amounts of water collect in the bottom of the trunk in the rear left corner below the spare tire. This continued for about two days, making me think that the leak was not resolved. However, after a couple of days (including heavy rain), eventually there was no more water in the bottom of the trunk. The seemed very odd to me, but I suspect it was simply water that had accumulated in other areas and was slowly making its way down? Very odd.
Regardless, the trunk has been completely DRY now for 4 weeks, including heavy rains and a trip to the car wash.
Lee




