The first 3 model years of 'vanagons' with radiators had what you call a
"real cap" on their tanks. They are a much worse POS than the later
threaded on caps, which mostly seemed to work fine for more than 20
years. You can see this early cap on Bentley page 19.4 and on 19.7

Mark

Larry Alofs wrote:
> I recently spent some time browsing at the local pick-n-pull, hoping to
> find a tank on some other vehicle that could be substituted for the vanagon
> pressure tank.  Ideally it would be functionally the same, except having a
> "real radiator cap".  I did not find such a tank yet.  I did find some
> radiators with long necks that could be cut off and they had traditional
> metal caps with provision for pressure bleeding and draw back upon cooling.
>   The problem would be grafting such a neck onto our tanks.
>    Of course I know there are those among us who believe that the VW
> engineers were much smarter than we are and we shouldn't tamper with the
> OEM design.  I just thought that I would throw the idea out there.
>    Over in the world of Jeep Cherokees there are those who solved a similar
> problem using a substitute from a GM product.
>
> Larry A.
>
>