It's a vent interconnect that's designed to allow gas to fill both sides
of the 'saddle' evenly.
  As you fill up, the level rises to a point where an air bubble would get
trapped on one side or the other.  The crosstube allows the trapped air to
equalize and vent to the overflow reservoirs.
  As you drive and the level drops, it will allow both sides to drain
evenly, also.

Mike B..
----- Original Message -----
From: "neil N" <musomuso@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, June 26, 2008 8:16 PM
Subject: Gas tank vent line questions

> Hi all.
>
> So why did VW put those steel (or plastic) tubes inbetween the
> connections to/from expansion tanks and the gas tank itself?
>
> Just curious.....
>
> I'll be installing continuous pieces of hose in place of these.
>
> Also, anyone have trouble getting the metric braided line to slip over
> the tubes on *aftermarket* gas tanks? I tried, but it seems like the
> fit is too  tight.
>
> Thanks,
>
> Neil.
>
> --
> Neil Nicholson '81 JettaWesty "Jaco
> http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
> http://web.mac.com/tubaneil
> http://tubaneil.googlepages.com/
>