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    Water Leaks = Fix

    Water leaks in the rear floorboard

    [ Ron Milliet :: 01 Jan 2000 ]

    I know EXACTLY what causes the "soaked floorboard carpet phenomenon" and how to fix it.
    This question has come several times recently and many times over the year. I **think** it is common to E30s and should be put in a FAQ.
    I spent HOURS and many gray hairs tracking down this DAMN problem. I COMPLETELY removed the interior of my car including the carpet.

    Problem Description:

    After a rain, the carpet in the rear floorboard gets TOTALLY soaked...usually visible, standing water. Close inspection reveals that the water is coming from UNDER the carpet and rising up to the top. This is different than the...dripping down from the sunroof leak, taillight lens gasket trunk leak, and the ever annoying under the dash from fresh air vent leak.

    Problem FIX:

    It was both passenger and driver floor boards. I wrestled this PITA problem for about one year, before I finally resorted to tearing the car apart.
    I finally pin pointed the rocker drains were not draining. They had been crushed closed by something. The sunroof would drain into the rocker and eventually fill up enough to spill over into the floor pan via holes for the wiring harness.

    This is very easy to test (details for an E30):

    Start with car on level ground and fill the forward sunroof tube slowly with water, it should immediately start streaming out as fast as you pour it in via the "fore" drain. The rear sunroof tube does not drain into the rocker.

    Next point the front of your car up a steep hill and again fill the front tube, the water should stream out of the "aft" drain.
    My car had two drains per side. These were merely indentions in the sheet metal seam. All 4 of my drains were crushed closed.
    I used a screwdriver to open them and was greeted with a rush of water held in the rocker.

    BTW, My car took on water once more after this. It happened when my car was parked with the front down a VERY steep hill. The problem was the "fore" drain is located about 8 to 10 inches from the end of the rocker. This allows water to pool up and spill over before it reaches the drain.
    This phenomenon was immediately remedied with a 1/4 drill bit!!

    Some more details on the "LEAK from hell"...

    Where does the rear sunroof tube drain?

    This should not be the problem **hopefully** and is VERY easy to test. The rear tubes run (of all places) into the trunk and drain out by the side marker lights.

    Just use a water bottle and with the car pointed up hill, pour the water into sunroof track so it runs AWAY from the front drain hole. It will look like the water just goes under your roof...I don't think you can see the rear drain hole.

    You should then see a stream of water coming out near the rear side marker. If it does not drain or drains some other place... this is a problem.

    Where exactly are these drains? Are these drains underneath the car?

    The rocker drains are hard to see...get a good light and crawl under there...remember...mine were CRUSHED so I actually saw them a DOZEN times and did not know it... you are looking for a "perforation" in the sheet metal right were the rocker "seams" with the floor pan.

    The "fore" drain is approx 6 inches behind the door/fender seam, then the "aft" drain is approx 6 inches in from the end of the rocker.
    These drains are SMALL, and are hard to describe... they are essentially indentions in the sheet metal.
    Pour the water with the car level first...and check where the water exits.

    Ron Milliet

    1. elephant trunk- Along with what this guy said, i cleaned out the "Elephant trunk" in the front of the car.
    the elephant trunk is located between the firewall, and the ignition wires. which should be located ontop of the cylinder head.

    2-trunk - also the drain in the trunk can cause trunk flooding if the peices are loose or not connecting.

    i first pushed fishing wire to see how far it would go. then did the coaxil route, along with small puffs of air

    i didnt use a compressor..i paid a kid in my neighborhood 10 bux to blow up the rubber tube. :twisted evil:

    then i silicone them to the black drainage peice.

    i also Re-sealed everything. taillights, sunroof, doors (i got a coupe), windows(side rear).

    i also reinforced the trunk pockets (under batter, and jack holder area) i sprayed that trunk liner from autozone. about 3 layers. USe tape so it looks professional.

    sorry no pics camera fell in the water. :hitler::hitler::hitler:(fucking dumb ass kid who got paid 15 dollors)
    Operation S/C E39M5.:woowoo:

    Not to bring back and old thread, but this thread appears to be the most comprehensive. I think I may have a problem with the rocker drains or rear sunroof drains....

    Elephant trunk is new, rear tail light gaskets are new, gasket(s) on the blower box/to firewall are also new.

    Does anybody have pictures of what to look for exactly? My carpet isn't wet, but I can hear water splashing behind the passenger door .... and it's not in the trunk area.

    Last edited by Jean; 11-01-2008, 04:26 PM.
    Mtech1 v8 build thread -

    OEM v8 manual chip or dme -


      i had the water appearing in the floorboards after the first hard rain with my car. vacuumed it out and figured i just had a leaky seal or something. next really hard rain, and i had standing water. found this thread and checked the rocker drains on the problem side. they were completely clogged with leaves/dirt. cleaned them out for 30 minutes and havent had a problem since. i havent had a problem with the trunk yet...


        I'll have to look tomorrow, hopefully I'll figure out what the problem is and hope it's not something in/or related to the C-pillar stuff/window....
        Mtech1 v8 build thread -

        OEM v8 manual chip or dme -


          the blower motor housing also leaks water under the carpet along the transmission tunnel, this problem is horrible to fix because you can't really replace the seal.

          I also get puddles in my trunk with all new taillight seals and antenna grommet. And my trunk seal is good. These cars leak!


            Originally posted by Jean View Post
            Does anybody have pictures of what to look for exactly?
            Jean, the rear sunroof drain is in the trunk vent just behind and below the antenna.

            Closing SOON!

            Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

            Thanks for 10 years of fun!


              My 318 does not have rear sunroof drain pipes in the trunk, the air vents don't even have provisions for them?

              I just came back from a hardware store with a 6' long 1/4" snake and got them down the front sunroof drain holes and can hear them go all the way down... I then pour water in the front sunroof drain holes and nothing came out from under the car near the front jacking point?! wtf Now, somewhere in the middle between the front and rear jacking points there is a plastic plug facing the ground on both sides of my car, when I removed it water came out...

              I did the same on my 325 and I can see where it's supposed to come out, but is it not the same on the early 318 cars? I don't see the rectangular slots like on the 325 where the water is supposed to come out..

              I open the trunk and see the rear drain pipes on my 325i but nothing on the 318?!
              Mtech1 v8 build thread -

              OEM v8 manual chip or dme -


                Any pictures of the undercar drains that can be "coated over"? My rear sunroof drains are leaking into my trunk even though water is flowing out near the rear marker.


                  my 87 e30 has a new leak thats ending up on the driver side

                  I havent had time to figure out where its comeing from... but i do know its comeing from by my left foot.... i see water some times hanging off the bottem of my hood pull...

                  think it just might be the door.. or the windsheild..... ahhh!!!
                  04 e83 X3
                  01 e39 540M
                  97 e36 328is

                  Specializing In BMW, Audi, Mercedes Benz, Porsche ,Volkswagen



                    Good test.

                    M52 |S52 Cams|E36 Rack Swap|GC Coilover Kit |. . . . . . . . . More To Come


                      Originally posted by Burning2nd View Post
                      my 87 e30 has a new leak thats ending up on the driver side. I havent had time to figure out where its comeing from... but i do know its comeing from by my left foot.... i see water some times hanging off the bottem of my hood pull...think it just might be the door.. or the windsheild..... ahhh!!!
                      I have the same issue! The water killed my George Graves window dimming module, filled it with water.
                      January 2012 COTM


                        Thanks for bringing back that thread Jean.I'm having that very same problem right now.
                        Driving me crazy.



                          Okay heres a weird one for you guys... I have a leak in my trunk ( 4door ) right where jack and all that rests, I cant find it. The walls are dry, tailights dry, it just sits in that well on the left hand side...anyone know wtf causes that? kause its starting to get annoying.
                          The 9mm is a .45 set on stun.:mrgreen:


                            Originally posted by Jean View Post


                            > Carey Grummitt <[EMAIL PROTECTED]> wrote:

                            > Drains: 101

                            > First off, be sure to remove the crud blocking a vent/drain. If

                            you just blow/push it out of the way... it will find it's way back and

                            clog a drain or vent.


                            > Sunroof:

                            > The best way to clear the sunroof drains- two on each side for a

                            total of four sunroof drains (and most other drains) is by compressed

                            air/air compressor. FYI: The front drains snake down the front door

                            jam (near the windshield frame) and drain out from within the

                            wheel-well (about/above where the speaker is located on the front

                            floor). You can't locate the end of this hose unless you remove the

                            fender- not that you need too, just to let you know.


                            > The rear roof drains- drain into the air vents located in the trunk

                            (battery compartment on the passenger side and the Jack storage

                            compartment on the driver side). Check and make sure the rear drains

                            are still draining out the vents, sometimes the steel clips that hold

                            them in place will rust and the water will then start to drain into

                            the compartments in the trunk.


                            > Compartments in the trunk:

                            > Both L/R trunk compartments have a small "slit" in the steel/bottoms

                            that allows water to drain in the event water should end up there.

                            You can see the slits/drains if you look under the car/quarter panels

                            just below the battery/jack compartments. The slits are only about a

                            1/2 inch wide and maybe have a very small opening of about a 1/16" for

                            water to drain. It's very common for the "slits" (in the trunk only)

                            to become full of dirt/sand/leaves in the aging E30's. It's best to

                            remove the plastic liner in the trunk about every 20 years (and the

                            battery) and fully clean/vacuum the crud out of the compartments to

                            make sure the slits remain clear (and hope that the tail panel has not

                            already started to rust out). Any on going moisture in this area is

                            the #1 reason quarter panels start to rust out in the rear- no matter

                            how well BMW rust-proofs the cars (and they do a fine job of doing

                            that). Also check for rust/holes in the steel along the rubber trunk

                            seal or rusted

                            > steel around the tail lights if you have on-going condensation

                            build up in the trunk (you should remove the tail lights for the best

                            inspection. This is a BIG problem for the E30's that have been in or

                            are from the Eastern US. Replace the trunk seal and seals on the

                            tail lights if water is leaking in and seal any areas of rust in or

                            around the trunk-deck or around the tail lights/tail panel area.






                              quoted from :

                              jean posted it a while ago - some very helpful info....

                              I am going to tackle this same shitty problem very soon..