Eric,

BTDT.  You have a "blown head gasket".  The only repair is a reseal.
First, pull the plugs and see which one is 'different' in appearence.
In my case it was #2.  Squeeky clean.  Having determined that there is
only one hole leaking, order up a single side head gasket set from Ron
@ Bus Depot. If leakage is indicated on both heads, you know what to
do...

There is no doubt a full procedure in the Vanagon.com webpage, but the
quick and dirty explanation is:

Pull the offending head, take it to the local machine shop for a
'pressure test' and if it passes, replace the stainless gasket at the
head/cylinder interface as well as the green o-ring at the spigot of
the cylinder.  Bolt it back together and it's fixed.

There just ain't no other way.  BTW, do not be tempted to try the
'Bars Leaks' fix.  It won't and next summer you'll be buying a
radiator.  BTDT too.

Jim Arnott
WetWesties
Union, OR