Date:         Sun, 11 Jun 2000 09:00:21 -0400
Reply-To:     Lawrence Johnson <larry_avery.johnson@SYMPATICO.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Lawrence Johnson <larry_avery.johnson@SYMPATICO.CA>
Subject:      Re: Cooling System Weirdness
Content-Type: text/plain; charset=us-ascii

Marc, I suspect that the cap on the expansion tank is either plugged or damaged
and is not opening at the correct pressure (14 lb. ?). If it were opening
correctly then that pressure that you observed would have opened the valve in
the cap and forced the entrapped air into the overflow reservoir tank.
Also, make sure that the hose from the expansion tank to the overflow reservoir
tank is air tight and connected securely. If it is not, then when the engine
cools and the expansion tank begins to draw coolant from the overflow reservoir
tank, instead of drawing coolant into the expansion tank it starts sucking air.
-Larry

Marc Perdue wrote:

> <snip>On the way back Sunday evening, with the outside temp at about 70, the
> coolant level red light came on and started blinking.  Having heard (okay,
> read) the horror stories here about blown engines, I pulled over immediately
> and started checking everything.  Temp needle was at about one-third, heat
> was about normal given there's no working fan, engine didn't feel very hot,
> and the reservoir was on Max.
>
> After I turned the engine back on, the light stopped blinking . . . until we
> got a couple miles down the road.  This time I pull into a gas station and
> start flipping through the manual.  This is the part where I find out about
> the coolant expansion tank, inside and to the left of the coolant reservoir,
> where the coolant level sensor is.  Aha!  The level is at minimum!  Of
> course!!  Problem is, how did it get there?
>
> I carefully pulled the small hose that connects the reservoir to the
> expansion tank . . . no pressure and nothing leaks out . . . so far, so
> good.  I start to loosen the cap on the expansion tank when all of a sudden
> there's a hissing sound and the expansion tank fills rapidly!  I tighten the
> cap and replace the reservoir hose and drive home with no further incident.
> What is going on here?  It seems that the expansion tank built up enough
> pressure to prevent any further coolant coming in from the reservoir, but
> what caused the pressure buildup to begin with?  Is this a symptom of a
> cooling system that needs to be burped?
>
> I'm looking forward to finding an answer to this one.  It had me a little
> nervous there for a while . . .<snip>