To test my inline VW motor for exhaust bubbles in the pressure tank I put
15 psi air pressure in there with all the sparkplugs out, then listened at
the plug holes.... I could hear my leaking head gasket....

On Jul 28, 2017 9:03 AM, "Neil N" <musomuso@gmail.com> wrote:

> This is likely moot, as it sounds like the cap(s) failed, but was the
> replaced blue cap and current cap tested? e.g. could you easily blow
> air through it or did it make a honking sound when you did so?
>
> My '88 also gushed coolant after a long hard drive then a bunch of
> stop and go traffic on a hot day so this may be wishful thinking on my
> part, but I often wonder if the valve in some brands of blue caps are
> built so close to the upper end coolant temperature of a typical WBX
> engine that if the engine is being driven in a manner causing it to
> run hotter than normal, (and maybe its also connected to a marginal
> cooling system) the valve in the cap fails due to the slightly higher
> temperature.
>
> I think this has been suggested here already but to test for a
> combustion or exhaust leak into coolant path, with the cylinder at
> TDC, could pressurized air be applied to each cylinder while watching
> for air bubbles in the coolant? Tough to re create the fault though.
> e.g. my engine coolant pressure tested fine while idling for at least
> 20 minutes.
>
>
> Neil.
>
>
>
>
>
> On 7/27/17, Eric Caron <ecaron1@comcast.net> wrote:
> > Hi folks,
> > So My 1.9 gas engine had a concern last year.  It seemed to be getting
> air
> > in the coolant system and then not bleeding out.  I never identified the
> > problem.  A friend gave me a original VW blue cap and my problem seemed
> to
> > go away.
>
> > Returning from a three hour pretty hard trip we noticed my van leaking
> > coolant.  It was coming out the top of the overflow tank. I decided to
> > continue the hour trip home as the temp was fine.
> >
> > No more coolant seemed to leak out.  Now that the van is cooled off the
> > reservoir is full and the over flow tank is empty.
> >
> > Last year folks gave me some good suggestions as to what might be going
> on.
> > As the blue cap seemed to solve my problem I chose to hope all was well.
> >
> > I think this cap is working correctly so my fear is that this means
> exhaust
> > gas getting into my coolant.
> >
>
>
>
> --
> Neil n
>
> Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>
>
> 1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>
>
> 1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>
>
> Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>
>