>ive seen a bunch of vanagons that have the lower edges of the rear hatch
>rusting out from behind, and bubbling up the paint, rotting right
>thru the metal.
>didnt think much of it till the other day after a torrential downpour the day
>before, i raised the hatch on my vanagon and a little bit of water dripped
>out from around the bottom of the hatch.  upon closer inspection i noticed a
>bunch of water was in the bottom lip inside the hatch.   standing
>water creates
>rust.. so i  was thinking of a way to let the water drain out of there, and to
>never build up in there again..  then i noticed the 2 black plastic round
>plugs in each bottom corner of the hatch..  i carefully pried these out with a
>small flathead as to not scratch the paint..  upon which i was
>immediately doused
>with water.  i removed these 2 plugs and will not ever put them back in, as
>they hold water inside the hatch, wich leads to rust..

Condensation, no doubt. Good ol' thoughtful VW. My Hiaces have drain
openings there...

Drains won't STOP rust in tailgate seams, but it will slow the initiation down.

I would suggest flushing the interior of the tailgate with detergent
to clean out dust deposits (which will HOLD water) and treating the
seam with rustproofing after it's thoroughly dry. Other doors too!
--
Regards
Andrew