I have never understood the use of the term expansion tank in
this context.  I believe that on American cars with "open"
cooling systems, the terms expansion amd overflow are often
used interchangably.  It's the tank where the extra coolant
overflows to when it gets hot and expands and doesn't all fit
in the radiator. A "closed" system on the other hand, is not
normally expected to overflow, and has a tank with an air
space to allow the coolant to expand when it heats up without
 producing too much pressure. This can be called an expansion
tank.
  When peering into the engine bay from the rear of the van,
the left hand tank is the "pressure tank" and the one on the
right is the "overflow tank". IMHO :-)

Larry A.

---- Original message ----
>Date: Mon, 27 Feb 2006 13:41:56 -0600
>From: John Rodgers <inua@CHARTER.NET>
>Subject: Re: [VANAGON] different expansion tank question
>To: vanagon@GERRY.VANAGON.COM
>
>Marty Kulmus wrote:
>
>>Thanks for all of your inputs. I am sorry for mixing my
metaphors, I now
>>know the proper names and locations of Mr. Expansion and
Overflow. I now
>>have to get work on testing.
>>
>>Marty
>>
>>
>>
>>
>Well, it's sort of like this. If you were  instructing a bunch of
>doctors on removing the appendix but were calling it the
uvula all the
>doctors would be looking in the throat trying to understand
what you
>were talking about.
>
>Ah, well. We all goof  it at one time or another, and me more
often than
>not!! :-)
>
>Regards,
>
>John Rodgers
>88 GL Driver
>88 GL Volksiebus Driver