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Trunk Leak

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  • Trunk Leak

    I searched, but didn't find anything definitive, so I thought I'd post some pics and a description of the problem.

    For the past couple of years, I've had trouble with a leak somewhere around the trunk, allowing the jack well to fill up with water during heavy rains. The car has been in a garage and not driven during an engine rebuild (17 months), so I forgot about it. That is until some heavy rains hit late last week.

    Popping the trunk open during the rain, there was a small puddle (< 1/2") in the jack well. However, I couldn't find where it was coming from (the sides all around the well were dry). Seeing that it wasn't that much (car is parked on a slight incline, nose higher than the rear) I figured I'd check it again after the rain stopped.

    When popping the trunk this morning, I was shocked to find that the well was near full, and the spare tire well also had a small accumulation. The carpet was soaked. I'm hoping this additional water was just because the jack well overflowed.

    Some pics:

    The condensation surprised me, but tells me that way too much water was making it in.

    I've tried chasing this leak a couple of times in the past, but I'm at the point that I'm not sure what to try next. At the very least, I'm going to start with tail light gaskets, but fear that's not it since the car was parked on an incline. Any additional suggestions of what I should be looking for?

    I'm hoping it's unrelated, but I have a small spot of rust on the seam where the C-Pillar meets the trunk:

    Thanks in advance for any suggestions.

  • #2
    Check to see if the small black hose that connects from the rear sunroof drains to the left vent in your trunk is secure. You can see the hose and vent in your first photo above. If the hose is loose where it attaches to the vent, then water can leak. Also, follow the hose up to see if it is cracked. The wheel well probably got wet from the overflowing jack area. I am not sure about the condensation, but once you find the jack area leak, check to see if the condensation reappears. That small patch of rust seems unrelated, but you should take care of it before it gets any worse. It is still very small, so should be breeze to take care of.

    I also had a small puddle in my jack area, so I think it is the same thing.

    Cheers, Daniel.
    Last edited by BeastPower; 10-29-2007, 09:57 AM.
    - 1987 M3 (e30)
    -- BeastPower Motorsports:
    - -Eisenmann Exhaust Systems:


    • #3
      also check the trunk seal itself. Fixed mine on the 323i this weekend and it had a rust spot right above the tail light.


      • #4
        Thanks guys, got back into it this evening with the above advice. The sunroof drain tube was secured in the vent. I also took out the stock amp to check the hose for cracks, as far as I could reach I didn't find any. To confirm, I opened the sunroof and poured a pitcher of water (at least a gallon) down the track, and it all drained properly. No water ended up in the jack area, and the outside of the tube was dry. Also confirmed that there was not even a drip or any moisture where the tube meets the vent.

        This one's really got me stumped. I've left the trunk apart, as I've got a bit more diagnosing to do.

        Any other ideas?


        • #5
          I had the same leak. Also on the pass. side, the battery tray would fill up.Car is always parked with the nose higher than the ass. Turned out to be the taillite gaskets. when I removed them, you could see cracks in them, like they were dry rotted or something. Replaced them and there are no more leaks.


          • #6
            Originally posted by jimmyC View Post
            I had the same leak. Also on the pass. side, the battery tray would fill up.Car is always parked with the nose higher than the ass. Turned out to be the taillite gaskets. when I removed them, you could see cracks in them, like they were dry rotted or something. Replaced them and there are no more leaks.
            Definitely Taillight gaskets :rastajake: The only other possible item could be the trunk seal.
            1989 E30 M3 Cabrio - Nogaro Sliver / Black - 1 of 786
            1990 E30 M3 - Sterling Silver / Black
            1991 E30 318is - Sterling / Black (Mtech II project)


            • #7
              Yep, tail light gasket. This is a notorious weak point in the E30 design.


              • #8
                I dunno guys- that moisture is pretty high up inside the quarter panel. I think there is a definite issue at the "C" pillar seam along w/ that plug. There is rust there starting already, that could be allowing the water/ moisture in there.... Check up inside the quater panel to see if the rust has (is) spread in there at the seam point (?)

                Best bet (to help try to isolate) the problem is grab a squirt/ ketchup bottle filled with water in it & work each area that looks suspect. Try squirting water in each area to see if it is leaking. Also lift up the rubber decklid seal around to amke that metal is all intact....

                Don McAdams
                1988 E30 M3
                "E30 M3 Owner & Enthusiast"



                • #9
                  I had a similar leak and it turned out to be the gaskets for the rear wing.. replaced them and it hasnt leaked since. luck?? not sure but it worked for me..cheers
                  88 M3
                  91 M5
                  90 325is


                  • #10
                    If you're interested, I have a pair of new tail light gaskets. My new tail lights came with new gaskets so I ended up with an extra set.

                    PM me if you'd like to buy them.

                    The rides-
                    '68 Camaro- 511hp tq. 388cid, Tremec 5 speed, Baer Brakes, Hotchkis suspension, 18" Budniks, Recaro seats
                    '73 2002- Metric Mech. 2200 efi, 5 speed, 3.90 lsd, Ground Control suspension, 17" BBS LM's, Recaro interior
                    '89 M3


                    • #11
                      whoa!..........why do you have a grommet where the plug should be??? That's basically a wide open area for water to enter and rot that pillar. Fix that IMMEDIATELY.


                      • #12
                        OK, giving some thought first to the condensation, I'm not sure that it's related to the leak. When I opened the car up yesterday, it'd been sitting in the sun for a few hours, so the condensation might have just been a by-product of the heat collecting in the closed trunk. I also noticed (in the cabin) that there was condensation on the heater core, which would also support that theory.

                        I haven't had a chance to do any more diagnosing, but hoping to pull the tail light off tomorrow to check. Will post some pics of what I find.

                        As for the rear wing, I was surprised to find that there was no gasket between the wing and the trunk lid (I took it off a few weeks back to wax the trunk lid). Checking realOEM, I didn't see that there should be a gasket. I've considered making my own, but not sure it's necessary.

                        Floss - are you talking about the clear plastic thing in the 4th pic? It's a full plug. Does that piece look different on yours?

                        Again, thanks for all the suggestions.