If you are talking about their still being pressure in the main pressure
bottle, the one with the pressure cap on it, on a stone cold engine
....generally that's not good.

I have seen a few cars, including vanagons do this, sometimes for a long
time, like years even, with no other symptoms.
It can only be that pressure from the combustion chambers is getting
into the cooling system.

you can try another pressure cap.You should have a couple anyway..those
blue caps can be weird.

Does it use coolant at all ? Like does coolant slowly dissappear ?
Most waterboxer vanagons use a tiny bit of coolant ...like an inch out
of the license plate bottle in a month or two.
That's common, almost normal, and acceptable.

if it uses more than that ...and you can't find any external leaks
(there are dozens of spots that can seep of course...such as rear heater
core , or near any hose clamp thoughpout the van ) ...
and it still uses coolant,
you start thinking about the heads and head gaskets.
All waterboxer engines need new head gaskets about every 8 years/80K
miles IMO ..
though of course people get over even 200K sometimes.   I shudder to
think of the corrosion that usually happens with heads left on that
long. Perhaps not always, but usually.

Corrosion is the main enemy of vanagons . I treat it constantly in
almost all systems.

On 5/7/2013 3:25 AM, Kurt Grotz wrote:
> I got my 86 out from winter dulldrums and drove 200 mile trip.  Noticed
> that reserve overflow was filled and the tank itself was low.  I drained
> some from overflow (when engine was sitting overnight) and then proceeded
> to open the main coolant tank to put in more fluid.  As soon as I loosened
> the blue cap pressure started filling it up from the rest of the water
> system.  I quickly tightened it down.  When I run it - it gets low again.
>   I have never had this problem of pressure being so great that I can't just
> simply take main tank cap off.  Could this be a bad cap?  It is a newer one
> which I got because it looked newer.   Can't seem to find the old one.
>   Ideas?
>
>
> Kurt Grotz
> 484-477-2109
> kurtgrotz@gmail.com
> 86 Vanagon (Rexmobile)
> 87 Westy (Sky)
>