As others have said, this rust is also on the inside between the spot welded
flanges.  Covering this up with anything, including weldment, leaves the
problem to continue on the inside.  Cleaning and rust killing if the metal
hasn't rusted though can buy time, but the only permanent fix is panel
replacement.  Then you can fill the seams lightly with flexible professional
grade body putty, which leaves the seam sealed but visible.   Polyester
filler will crack.

I don't like the idea of welding.  The seams are part of the character and
originality of an '80s van, and cleaning up the bead would be a lot of work,
possibly more than panel replacement.

I feel your pain. I've been through this with my MGBs many times, but they
have far fewer seams, and they are leaded. (Yes, I've done leading, and it's
really not that hard.)

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Liberte, Joel
Sent: Monday, November 19, 2012 7:33 PM
To: vanagon@GERRY.VANAGON.COM
Subject: '90 syncro with seam rust

Nothing unusual about having it and I'm figuring out the best way of dealing
with it before we start dumping massive amounts of salt on the roads around
here.

It was suggested to me that after cleaning the seams of rust to weld them
together to prevent it from happening again.  Other than the obvious thought
of the additional difficulty of removing any panel in the future if needed
and some additional body work to smooth them out before repainting, are
there any other items that would suggest welding the seams is a really bad
idea?

Joel