Wouldn't having the system under a slight vacuum favor larger bubbles
and thus easier removal of said bubbles?  I would think a system under
pressure might allow for gasses to be dissolved into the liquid and/or
any bubbles would be reduced in size and may not move as freely.  I
guess it depends on the amount of pressure/vacuum, as I am thinking
purely theoretically. :-)

aloha
Mike Braden

Gerald Masar wrote:

>Darrell Boehler has written up a procedure on filling and bleeding the coolant system
>under pressure, using a bicycle pump. I don't have ref to it right now, but it's in
>the archives.
>----- Original Message -----
>From: "John Carpenter" <Trvlr2001@AOL.COM>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Tuesday, March 02, 2004 8:41 AM
>Subject: Re: vacuum bleeding?
>
>
>
>
>>Much easier to use pressure.
>>I put a quickchange fitting on my coolant tank.
>>hooked it up to my compressor, set at 15 lbs.
>>I bleed the coolant manifold/hose.
>>but that was before reversing it.
>>Dont need to do that now.
>>2nd, bleed the radiator.
>>give the bus a rocking motion,
>>till the bubbles stop.
>>JC...
>>
>>In a message dated 3/2/2004 9:46:09 AM Eastern Standard Time, wlail@OU.EDU writes:
>>
>>
>>
>>>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
>>>
>>>