I've been a keen 2CV enthusiast for 10 years now, but I fear it's coming to a sad end soon with me selling all my cars, if I don't get a solution for two issues that have been haunting me for a long time now. One is the F****** went flap!!

I have two cars, both leak water through the went flap. The first one leaked water inn through the holes in the back of the flap. It was watertight along the rubbergasket. So I took it off the car, and sealed it along the joint where the rubber gasket is placed. First time it did't work so I did it again, with all the dismantling and mounting, and it still leaks. After maybe 6 hours of work on the old flap, it still leaks. So I ordered a new flap for that car. Not yet tried the new flap, I must paint it first.

The second car is newly built. New vent flap from Der Franzose, which one should NEVER buy parts from.(Based on a lot of reasons) It was a production fault, with the two parts it consist off, welded together crocked. Didn't notis it before after paint, when trying to mount the rubber gasket. I drilled the spotwelds and got the two parts separated without damaging the paint on the front. I then glued the two half's together with Tec7 and it seems to hold well. Mounted the flap and it leaks like hell at the corners. Took it off and with bending and twisting it, and dosens of trial fits, it finally seemed tight. When looking from the inside I could't see the light from the flashlight on the outside, moving it along the edges.
Mounted everything together including windshield wipers and dashboard. Testing with water afterwards, revealed that it leaks. A lot.
So beginning to get seriously fed up about all this, I ordered a brand new, stainless steel one. With gasket and everything. Mounted it today and guess what....Cant even get it to keep the light from the flashlight out.
Twisted, bent.... Probably spent 12 hours on this issue on this car, and
money for two complete vent flaps. I don't know what more to do.

I should mention I've changed 4 flaps on other cars with no problem. One of the two whos making me mad now, I changed the flap 10 years ago, and it's been 100% watertight until now. So I haven't had problems before, why am I constantly failing on these two cars now???!!!!

Help me keep my sanity!!!

The vent flap maybe flat/straight, what about the car?

Are you sure that the water ingress is via the vent flap. Usually it isn't. It is much more common for the wiper spindles to leak. Also the windscreen rubber not sealing or the spot weld access holes not being covered after any work in thone areas.

In my 2cv the water was coming through the vent flap at some point, but after doing all the usual fault finding with no success, I discovered two small holes under the windscreen rubber. The rain was getting through here into the vent of the at the top edge and then out of the vent flap at the bottom, making me 100% certain that the flap was leaking somewhere. Repaired the holes in the windscreen frame, leak stopped!

Yeah I should have mentioned that the windscreen has been removed on both cars, any rust have been dealt with. The windscreen surround are good and not leaking. The wiper spindles are good, also fitted with the rubber cover from brake cylinders. That's a good tip!

I can clearly see where the water comes from, on both cars. And it's the vent flap.

Can't see anything unusual about the body.
And it was waterproof earlier, but not now. Body is the same.

...and the spot-weld access holes and the seams between inner and outer panels were re-covered after painting?


If the seam or the spot-weld access holes are letting water in, it can trick you into thinking it's the flap, particularly at the ends

AHA! I wondered what the holes and bits of tape were for!

First check if the edges of your vent opening are straight. Than put in an soft insulation tape in the deeper area around the opening (must not be sponge like and hold water) Bottom half and up to both sides (large U-shape). Then mount in the flap with the little screw-rail.On the top side put the black kit that is used to install windows (3M). Last possible option pull a piece of rope drenched in Tectyl between the flap and the rubber (picture 2) This will bend the rubber slighty more in to the edge were it should close/seal.

Bending the flap slightly worked well for me. Just a little, the flap on its back on a stool or something and pushing down the ends. So that the edges are in firmer contact.