This could be lots of things. Not really. Sounds like a head leak around
the gasket or a crack. If you release the pressure with the engine cold,
then start the car for say 30 seconds or less, do you then get escaping
gas? Or is it the kind of thing where you have to do some hard driving to
get the pressure in the tank?

A sniffer kit from a parts store will tell you, or you can have the test
done at a shop.

Jim

On Fri, Jun 17, 2016 at 3:31 PM Eric Caron <ecaron1@comcast.net> wrote:

> OK folks,
>
>         Be gentle here as  coolant questions way to often end up with very
> scary responses.
>
> I’ve noticed that even a few days after a bus trip the van has air in the
> expansion tank.  usually the tank is about 3 fourths full.  If I turn the
> blue cap I hear bubbles and sound of pressure.  today a sighted friend told
> me that when I did this the expansion tank filled up with coolant.
> Interestingly the level of the over flow tank never seams to change.
>
> The van was recently checked out at a VW shop and he was suspicious that a
> tiny seep of coolant might be coming from one head but it was so slight he
> could not be sure.
>
> So, my van seems to build up pressure when running and holds it for
> several days.  Once released the expansion tank fills but level of overflow
> seems consistent.
>
> Is this normal or a sign of something needing attention.
>
> temp indicator is consistently just below the led.
>
> Eric Caron
> 85 GL Auto Westfalia
>