74 Charger heavy condensation inside deck lid? WTF??

1971 - 1974 Mopars

  1. 64fury74charger

    64fury74charger Well-Known Member

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    The underside of the deck lid is raining inside the trunk. This has been a real issue and I am not sure what to do about it. When I did the vinyl wrap last summer I also addressed several water issues in the rest of the car including a large hole that was under the lower w/s trim on the left side that drenched the carpet under the pedals. Sealed up the back glass as well.

    The trunk weather strip is in really good condition and seals better since adjusting the lid. There used to be small puddles of water in the rear foot well areas from the back window but that has been resolved. I was thinking that all the moisture inside was causing the large amounts of condensation in the trunk, but it seems like that isn’t the main problem.

    I also have car covers and that’s not helping either. Is there something I can try??:BangHead::BangHead::BangHead:

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  2. SureGrip

    SureGrip FBBO Gold Member FBBO Gold Member

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    Throw a few large pails of Damp-rid in the trunk and see what happens.

    Could be a lot of trapped moisture in the trunk/floor area that's not getting dried out and condenses when it warms up.
     
  3. Hijinx

    Hijinx FBBO Gold Member FBBO Gold Member

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    I would dry it, put a fan inside for a 1/2 hour or so... then lay inside the trunk while someone hoses it all up and see if anything is getting in from the outside.
     
  4. 66 Sat

    66 Sat Well-Known Member

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    Use the fluffy dog to wipe it dry?
     
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    • Nevada dan

      Nevada dan Well-Known Member

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      are you leaving your car outside in the damp air? if so ya your car is pulling the moisture from below it and a cover wont do much if not make it worse
       
    • 64fury74charger

      64fury74charger Well-Known Member

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      I have emptied the trunk and checked the entire trunk floor area from the top of the hump and both lower quarters, under the rear shelf and didn’t find any problems. Put large damp rid containers and they were full after about a week or so.
      Car is mostly parked on a large crushed compacted rock area that is about 10” deep so that should help keep from sucking moisture up from underneath.

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    • JDmac72chrgr

      JDmac72chrgr Well-Known Member

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      Pull front corner A pillar chrome, check "overlap" of cowl is sealed commomn issue: check cowl center drain inside wall, found holes there from years of debris stuck in drain: the rug moisture could be causing trunk condensation, needs air to escape/breath. Hope rugs & underside insulation are dry, if not, need drying asap. GOOD LUCK TROUBLESHOOTING
      John

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    • JDmac72chrgr

      JDmac72chrgr Well-Known Member

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      Do you have vapor barrier between cabin/trunk & behind ALL interior panels inside cabin?
       
    • 64fury74charger

      64fury74charger Well-Known Member

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      Car is usually parked on large crushed and compacted rock area to help minimize this. I am just not sure what else to do. :BangHead:

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    • 64fury74charger

      64fury74charger Well-Known Member

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      There is some of the original “stuffing” behind some of the panels but not much. What kind of vapor barrier should I use and where do I put it in the car?? I have laid some sound deadening on the back seat and floor. Any advice and information would be great. Thanks again.
       
    • 64fury74charger

      64fury74charger Well-Known Member

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      There was a large hole on the lower left of the A pillar that let water in above the driver’s side and that issue was resolved when I had a new windshield installed. The drain hole below the wiper motor is open as well. Thank you for your help.
       
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      • eldubb440

        eldubb440 more miracles than Jesus FBBO Gold Member

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        if your carpet/padding ever got wet, it probably still is
         
      • JDmac72chrgr

        JDmac72chrgr Well-Known Member

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        A pillar corner is common, glad that is done; check metal overlap area towards center of cowl just before cowl opening, may look sealed but "sealent" may be hard: check drain's WALL inside car, small rust holes may be present, wetness of carpet at top of trans tunnel dead giveway, USUALLY insulation covers this area inside car: moisture barrier is actually heavy plastic like thick trash bag that is glued (3M adhesive that is black) to metal structure of entire cabin, doors, and behind rear seat back glued to x-beam, along top, bottom and inside wheel wells to isolate trunk from cabin.
         
      • 64fury74charger

        64fury74charger Well-Known Member

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        Thank you for your help with this issue. I will have to plan on redoing the inside and the trunk areas with some type of plastic vapor barrier. I am considering replacing the carpet now that the inside is dry. Does the plastic have to be glued to the entire piece or can it just be around the edge?
         
      • JDmac72chrgr

        JDmac72chrgr Well-Known Member

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        Perimeter and middle areas to hold it in place. Pretty much the way factrory did it. Forget denier (thickness) that was used but going thick with mine, NJ weather.
         
      • JDmac72chrgr

        JDmac72chrgr Well-Known Member

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        Underdash, check cowl drain's wall inside, arrow pointing to in pic

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      • YY1

        YY1 Well-Known Member

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        Did you check the base of the vent "stacks" inside the cowl?

        That's super common and not real easy to fix.
         
      • Nevada dan

        Nevada dan Well-Known Member

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        even here in southern Nevada when the conditions are right your going to get moisture on the bottom side of metal, I was out in my back yard one morning the sky was clear it wasn't very cold , I have a 20 by 40 steel building with a concrete floor totally closed on 3 sides and I hear the sound of rain I walk into the building and it's pouring like rain all over everything I go back out and the outside is dry I look up and there's not a cloud in the sky , I had to close in the front and put doors on to stop it from happening , so when the humidity right I don't know if you can stop it short of moving the car indoors
         
      • JDmac72chrgr

        JDmac72chrgr Well-Known Member

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        64fury74charger,
        This the vapor barrier on the drivers door that I was refering to: all interior metal on sides & behind seat should have these if not mistaken.

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      • JG71B

        JG71B Well-Known Member

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        There's going to be moisture coming up from those rocks as well
         
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