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Wet floor


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now that rainy season is in full swing here in the bay area, it appears i've got water leaking into my car. there's a puddle on the floor behind the passenger seat. its drying up out there today, but before i investigate i thought i'd ask you generously knowledgeable folks- has this happened to anyone else? is there an obvious place to look? the door seal maybe? it doesn't seem to be coming in through the sunroof- the headliner is dry, but it could it be the drain tube? a hole in the floor pan?

thanks for any insight!


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- gasket around the door window, especially at the B-pillar

- rear side window gaskets or windows not closed tightly against the gasket

- trunk gasket possibly.

John in VA

'74 tii "Juanita"  '85 535i "Goldie"  '86 535i "M-POSSTR"  

'03 530i "Titan"  '06 330ci "ZHPY"


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Guest Anonymous

Try to determine if it comes in when stationary or moving. Hose the car down and see if it fills up with water. If not, look under the rear seat for rust holes in the wheel well.

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besides the places already mentioned, do this:

Pull the back seat, cushion and backrest and look for water streaks down the sheet metal behind the seat back, ending in a wet spot under the seat. If you see one, then pull out the package shelf trim and look at the backlight gasket. If it's original and old, it's hardened and allowed water to penetrate. If you're lucky, a new gasket will fix the problem. If not, you'll find the lip that retains the gasket has rusted away in spots, and will have to be repaired before installing a new backlight gasket.

If you don't see any streaks, carefully examine the floor under the seat cushion for rust spots, especially where the rear subframe reinforcement is welded to the floor pan. Rusthrough there will cause leakage and eventual subframe separation from the car (not a Good Thing!)

If you don't fix this, your floor is gonna rust out

Hope it's something simpler.


'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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Greetings from Vancouver, the "Wet Coast".

I'd almost put money on the rear window seal. Rubber seal deteriorates and leaks. Not visible to the eye, but a hose on the window will quickly show it streaming inside.

Check under the rear seat. There are spaces for moisture to move forward onto the rear floor.

I had this happen as well on the windsheild seal into the front passenger floor.

A quick fix is a small tube of silicone sealer, with the pointed tip well under the window seal as you squeeze silicone around the seal. Seal rubber to body on roof, rubber to glass on the lower area. Worked like a charm for me, 15 years ago, when I had a lake in the passenger side floor front and rear.

73 Inka Tii #2762958

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thanks a million everyone, for all the suggestions! time to get methodical.

but indeed- the rear window seal is most intriguing. i actually replaced it some months ago when it was dry, whilst replacing the headliner, and not only did i not silicone it, but the lip was a little rusty. i treated it with por-15, but it wasn't comprehensive. so i'll start there.

very much appreciated!



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easy to remove the back seat bottom and back rest

garden hose running on roof

you sit in rear of car with flash light and watch for the

water trail entering

Front windshield and back window rubber seals top the

common leak source

sunroof in your car? - drain tubes dump water into the rear

passenger quarter panel wells - watch it as you sit in the rear

door vapor barriers

door seals

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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Guest Anonymous

If you don't fix this, your floor is gonna rust out

Hope it's something simpler.



Head gaskets, 7 feet of snow and been workin on weatherproofin since November when I installed a new sunroof panel, what do you know about the rear interior sunroof seal, this is the one hidden completely from view when sunroof is installed, have searched but found that it is NLA. My panels seal was worn down to nubbins and with the first storm had a puddle in rear floors, installed some home weatherstripping to get by til I found correct seal. Any chance of a source or even a pic to replicate this seal, I know its important as with temp fix the problem is solved. When you say backlight do you mean rear window, still learning here. An honor to share with a o2 Valadictorian here on faq.

Dave Miller


76 Golfie, Screamin Yellow Zonker

97 328is For when u absolutley positively gotta get there fast

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