Date:         Thu, 4 Mar 2004 03:49:06 -0500
Reply-To:     "Daniel L. Katz" <katzd54@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Daniel L. Katz" <katzd54@YAHOO.COM>
Subject:      Re: Purging Cooling System of Air / Where Would We Be Without
              This Topic?

interesting. seems like a reasonable approach for initial fill. but isn't
the tall filling reservoir in back coupled with open vent in front just
another artifice for providing a pressure difference?

i would be surprised if this method alone purges all the air.


>Don't waste your time: the thermostat housing gets filled from both sides.
>Anyway, if it needed a weep hole, you can rest assured that VW would have
>punched one in the thermostat plate.
>
>All these suggestions to put pressure or suck on the coolant system when
>filling it demonstrate a lack of understanding about what is happening.
Looking
>under a Vanagon will reveal the tortured route the coolant lines have to
>follow.  The facts of life in this scenario are that air is less dense
than water
>and air is a compressible fluid while water is an incompressible fluid.
There
>are several places in the coolant system where air pockets can form which
will
>be unrelenting and sorta invisible to any pressure or vacuum they might
see.
>
>The solution I found to purging ALL the air from the coolant system is to
>rely on the laws of nature which rule the palpable universe.  First, get
the van
>up at the front at least the height VW specifies.  Jacking the van to this
>height can be risky for the average shadetree type, but, finding a
suitable
>gradient to avoid hoisting the van is not impossible.  Looking around
armed with
>some mason's twine and a line level should reveal one.
>
>Secondly, install an additional vent at the highest point of the system.
>
>Thirdly, at the rear of the van, connect a temporary filling reservoir
well
>above the elevation of the highest point in the system.
>
>There are some other minor things which make the job a little neater to
do,
>but are not essential such as attaching another temporary reservoir to the
>radiator vent.
>
>George