I can't imagine why anyone would suggest it's okay to plug that outlet on the cap. 

It's a pressure release design so that your system doesn't build up too much pressure. 

At least with your current situation you're able to keep on motoring down the road after a brief interlude. 

That wouldn't be happening so easily if you blow a hose. 

________________________________
From: Tom Rowsell <86westy@GEOEXPLOITS.ORG>
To: vanagon@GERRY.VANAGON.COM
Sent: Monday, August 22, 2011 2:02 PM
Subject: Re: Coolant Strangeness

Thanks Scott, of course I have no spare. I suppose plugging the hose
outlet on that blue cap is not wise? Is the cap used on any other VW
model just in case I find a junkyard ?

On 8/22/11, Scott Daniel� - Turbovans <scottdaniel@turbovans.com> wrote:
> that blue pressure cap ..
> is my first thought.
> They are not that reliable.� One should always carry a spare.
>
> right now, with no further information or test results..
> it sounds like ..
> either pressure cap is not holding pressure properly .....
>
> or cooling system pressure is abnormally high ( such as combustion gases
> getting into cooling system at the heads or head gaskets ).
> If you see bubbles btw...
> rising to the surface of the coolant in the pressure bottle
> ................unless you are in the process of just filling the coolant to
> start with ..........that is not a good sign.
>
> if you *always* see a small bubble trail there ...
> that's really not a good sign.
> Have the air space above the coolant in the main pressure bottle sniffed
> with a smog sniffer. If there are excessive HC's there ....it's a combustion
> gases getting into the coolant issue.
>� It should not do what you are descibing at all.
> Try the cap first though ..
> as it's so easy to do, and they are known to be a bit dodgey at times.
>
> Scott
> www.turbovans.com
>
> ----- Original Message -----
> From: "Tom Rowsell" <86westy@GEOEXPLOITS.ORG>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, August 22, 2011 11:08 AM
> Subject: Coolant Strangeness
>
>
>> This is likely an FAQ...I'm on the road and searching is awkward with
>> cell phone.
>> It seems when I drive for an hour or so at highway speed, and stop
>> abruptly (to get gas for example) coolant rushes from the left tank
>> into the overflow one on the right, sometimes overflowing that one
>> onto the ground. In one instance the dash light began to flicker and
>> when I pulled over, the right hand tank was full, and the left one was
>> down 1/2 litre or so. It's not overheating, but temperature rises at
>> idle after a highway run.
>> 2.1 litre, recent (last 6 months) new rad, water pump. There are no
>> evident leaks, and oil on dipstick looks clean.
>> Any suggestions on what to check?
>> The needle is generally parked right at the center of the LED...
>> Thanks
>> Tom
>
>