I'm not sure about the gasket, I've never noticed any of my vanagons
having one on that tank.

If you are filling the tank and it's going down, it sounds like it
working as it should work. If you had a leak  somewhere, air would
probably get sucked into the system as it cooled (instead of the
coolant from the tank through the one way valve) and the tank level
wouldn't move.

Try checking it when it is hot after a drive, then again the next
morning and see if there is a difference. If the level is low after
the drive, you've got a problem.

BTW, you probably already know this, but a lot of air can be trapped
up in "heater hill" and it can take several filling and cooldown
cycles to work itself out.

It helps a lot if the thermostat and heater are wide  open when you
fill, but I know that isn't always possible.

Jim

On Tue, Dec 7, 2010 at 5:03 PM, Michael Sullivan <sandwichhead@gmail.com> wrote:
> The tank behind the license plate was empty after I replaced a hose and
> bled. �I have added a full amount twice, and still that tank is empty. �The
> second time I filled it I found a rubber gasket in the tank about the size
> of a silver dollar. �Not sure where it came from but I put it on the OUTSIDE
> of the filler neck and screwed the cap on....Does it go there?
> Thanks to all.
> Michael in San Antonio
> 91GL Weekender AT 2.1L 'Gringo'
>