Water In the Cabin


Someone wrote - I have been experiencing water getting inside my '70 Bug. When it's raining and the car is parked outside, water gathers under the back seat on the driver's side, and there is rust in that area. Both the pop-out window seals and the rear window seal are fine.

When it's raining and the car is being driven, water comes in from the front by the pedals. There is some rust there also. I think the water is coming in through the gap where the body meets the floor pan.

I have some POR15 coming, and I am going to fill in these areas in the floor pans.

Rob responded - There are several possibilities that come to mind.

  • The body/pan seal might be leaking. This seal runs along the sides under the doors, across the front over the tunnel near the pedals and across the rear under the rear seat.

    Check that the bolts under the floor pan are snug/tight and also the four larger bolts under the front door pillars, plus the bolts under the back seat (inside the car) - these are all part of the body/pan sealing. They don't have to be super tight - I forget the torque, but well snugged up - they should compress the seal without squashing it completely flat.

  • The pin holes in the floor will certainly let in some water when the roads are wet. POR15 should seal pin holes OK, but it won't cover larger holes. If you have some larger holes, you could try fibre glassing over them before applying the POR15.
  • Note: You might not be aware that you can buy new floor pan sections - either just the rear area or complete sections for each side - from pedals to under the back seat. These can be pop rivetted in place with a sealant, or better yet - welded into the pan after the bad sections are cut out (leaving a lip for the new sections to sit on).

  • Have a close look at the drains under the doors - if these block up the door can fill with water and might possibly spill into the car when it's sloshing around - unlikely, but a possibility.
  • Remove the air box just in front of the windscreen and check that the L shaped plastic funnel and paper (!!!) drain tube underneath are clear. If these block up any water getting into the air box will flood into the bodywork under/behind the tank and can leak into the cabin, run down the front of the bodywork above your knees, along the floor and head for the under-battery area (you'r right - that's the lowest point in the floor pan). If the cheap paper drain tube is blocked or squashed and unusable, try finding some garden hose or plastic tubing which will fit the plastic L piece, and run it down the hole to make sure the area drains properly.

Some one else wrote - I have a wet floor at the backseat and at the driver's floor. the carpets/floor coverings are all soaked up. I don't know where the water is coming from.

Rob responded with some more good information -

There are several places that water can get into the car.

Look under the bottom edge of the doors and make sure that the drain slots in the bottom of the door are clear. It's not likely but blocked drain in the door could fill the inside of the doors up with water and maybe leak it into the cabin.

Make sure that the window rubbers are in good condition.

Does your car have eyebrow vents just behind the rear quarter windows? If it does this is a possible source as there is a vent right into the cabin and the space between the inner and outer skin of the car is open there so any water getting into the vents could flow down behind the inside side panel (next to the back seat) and out on to the floor from under the back seat.

Does your car have a fresh-air box inside the luggage area just in front of the windscreen? Underneath this box is a drain hose which runs down to a slot in the bodywork just near the fuel tank. This hose and the slot MUST be clear or water can get into the luggage area and drip into the car. The original drain tube is a sort of treated paper tube and these can fall apart so if you need to replace it, find some plastic hose of the right size. Since the floor slopes slightly to the rear, any water getting into the cabin there will slowly soak all the carpet from the front to the rear.

Since you have had a problem with water, remove the battery and check the floor under the battery for rust - it's very common anyway and water inside the car would make it rust worse.

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