Date:         Tue, 2 Mar 2004 17:19:50 -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: vacuum bleeding?

very interesting idea, and would work in principle. perhaps a closed loop
system returning coolant from exaust side of pump to open expansion tank
would facilitate lots of circulation without making a mess or wasting
coolant. also, this would be very safe for the cooling system, in terms of
working at or below atmospheric pressure. still could be some trapped air,
but worth a try, especially with a hefty pump. sounds like a fun project.

now, one point to remember is that there is no such thing as pulling on a
fluid. in fact, the higher pressure on the side open to the air pushes
fluid toward the vacuum side.

i have an '84 1.9 l to contend with, where there is always the problem of
no bypass around the thermostat. one method i used went something like
this: van was parked with rear end raised, expansion tank highest point in
cooling system, engine cold, just water in system, cap off expansion tank,
bleeder screw removed, two bolts that fasten gooseneck to thermostat
housing cracked open. with expansion tank kept full of water, air was
forced out of big return hose and gooseneck under thermostat, water
flowing out until i snugged down the two bolts. then pure antifreeze
(denser than water, pushing water ahead of it as it falls toward radiator)
was poured into expansion tank until the "water" coming out of the open
bleeder (lowest point) turned green (i then had about the right amount of
anti-freeze in the system) and the bleeder screw was replaced with
greenish "water" still flowing out until it was snug. at this point, in
theory, the van should have had a solid column of roughly 50/50 anti-
freeze solution, with no trapped air. but, i started her up and ran the
engine at 2000 rpm for some time in this position, with the cap to the
expansion tank still off. she took more coolant (now 50/50 mix), and i
imagine some bubbles did eventually exit from the open expansion tank as i
circulated the coolant this way. ever after, nothing but 50/50 anti-freeze
mixture added to overflow tank, and no trouble with air in system,
although i have from time to time bled very modest amounts of air out,
just for kicks - system seems to keep itself pretty much free of air
(knock on wood!).

dlk



On Tue, 2 Mar 2004 08:46:09 -0600, Warren.K.Lail-1 <wlail@OU.EDU> wrote:

>Has anyone ever thought of a way to bleed the cooling system on a Vanagon
by using a vacuum pump?  Would it be possible to hook up an electric pump
of some sort to the bleeder valve on the radiator, turn it on, and then
while someone keeps the reservoir topped off, run it until it runs free of
bubbles.  Just thinking of a way to totally bleed the system ...
>
>Warren Lail
>88 Westy "Billy Bones"
>87 GL