Discovered the cause of water getting into the trunk of my '95 Contour is the air vent on the right side, under the fuel door release pull.

It seems the gasket on this vent is a sponge, not a rubber gasket. It's soaked. Not tears in it, it's just water-logged. The plastic ears on the vent seem to be holding the assembly tight enough to the body opening.

How can I seal this? Looks like too large a gap for RTV sealant. Is a rubber gasket available?

Bumper has to be removed for access, to properly seal around vent, although some have had success sealing from inside.

My gasket was in pieces when my trunk was leaking, but I got it sealed up without going to the outside.

The vent itself is able to be removed from the inside. I think there is a springy plastic clip (it was a year ago, I don't remember too well) or something of the like. The I put on A LOT of silicone and put it back in place. Then more silicone around the edge. It didn't look perfect, but it's hidden so it doesn't have to.

[Raises hand] I sealed it from sucessfully from inside[knocking on wood]. The gasket piece cannot be purchased separate, you have to buy the vent as well IIRC...wasn't it like $70? You should remove the bumper if you want to do it right and avoid potential problems down the road, but it can be done from the inside. Good luck. I have fixed leaks in 3 different locations in the trunk, all on the passenger side.

The part number is F5RZ54280B62A. It's called a grille. It's not too
much
work. You need to remove the plastic piece covering the trunk lock area
and
then remove the carpet on the side of the trunk. To get the plastic
piece
off, you need a phillips screwdriver for the four plastic screws (be
gentle
with the screws). There are also two plastic pop rivet things you need
to
remove. The carpet is held in place by a plastic screw and two plastic
pop
rivets. Once you remove the carpet, you will see the black plastic vent
that
you just bought. Remove the new gasket from the new vent;
unfortunately, you
don't use the new plastic vent because you'd have to remove the bumper
to
install the whole assembly. The vent snaps into the sheet metal. Remove
the
old gasket from the old vent, clean the vent and sheet metal as best
you can
(for a good seal), and then insert the new vent seal into the old vent,
making sure that you insert the curved part of the gasket into the
curved
part of the vent. Make sure that the new gasket is firmly seated in the
vent. This takes some time to work the gasket into the vent because
there is
not a lot of room for your hand, but if you are patient, the whole
gasket
eventually will be well seated in the vent. Snap the vent back into the
body, being sure to position the bottom of the vent in the metal first.
You
shouldn't see water leaking through the vent anymore.

What were the othere locations on the passenger side of your truck where you had/foxed water leaks?

I might as well look at those while I'm repairing this....

Around the black vent, the hole where the antenna is(mine is regular non-powered), somewhere in the backglass(It would come in through the urethane used by the factory to install the backglass and drip down the hole where the trunk lid arm goes into when you shut the trunk, best way I can describe it ). Hope you find your leak(s).

i had the same problem on my drivers side. my trunk would get SOAKED! i checked the air vent thing and it seemed fine untill i inspected it further. come to find out, only 1 out of the 2 plastic clips were holding it place, therefor it was loose. so i bent the clip back up so its in tight and now i have no leakage.