No, it's brilliant and can work just fine.

a member on dieselvanagon gave a similar test.
Said ...start the engine cold....run it for 30 seconds...
shut off engine, open cap. If there is pressure there when you remove the
pressure cap ...
yup .....exhaust and combustion pressure are getting into the cooling system
.
it's same test as the latex glove test.

I love 'tricks' like this too.
Scott
www.turbovans.com

----- Original Message -----
From: "Don Hanson" <dhanson928@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, April 28, 2010 6:31 AM
Subject: Headgasket diagnostic "trick"

>  Paging around on the VW Vortex Forums to gather info on my probable
> headgasket failure and replacement.  Saw this suggestion to see if you may
> have a blown headgasket...
>
>  They say stick a latex glove over your pressure tank cap and start up the
> vehicle.  If the glove 'waves at you' by filling up with leaked gasses
> coming into the pressure reservoir, you got the leaky gasket...I thought
> that was pretty clever.  Love little 'tricks' like this...
>
>  Don't bother telling me this is NOT gonna work...I already know there are
> probably dozens of reasons why this is 'internet crap'...but it can work
> sometimes, I bet.
>
>  Don Hanson