Could also be the dreaded crack in a head between an intake and exhaust valve.Same symptoms as JOHN described.

> Date: Tue, 28 Apr 2015 18:54:16 -0500
> From: jrodgers113@GMAIL.COM
> Subject: Re: 2.1 WBX Coolant Loss: Searched
> To: vanagon@GERRY.VANAGON.COM
> 
> I just went thru this.  Head gasket leak. Exhaust gases pressurize the
> coolant, forcing it out of the reservoir into the over flow. the only
> way to really confirm is to do a sniffer test on the coolant. Exhaust
> gases will show in the coolant.
> 
> JOHN
> 
> On 4/28/2015 5:32 PM, Neil N wrote:
> > Hi all.
> >
> > After a recent 300 mile trip, noticed coolant bottle was empty,
> > coolant expansion bottle about 1/3 empty. This may have occurred over
> > more miles but was a relatively "sudden"
> > event. I suspect coolant may be getting burned at highway speeds. Details below.
> > ced all cooling system parts except for front-rear
> > heater cores, hoses heat control valves. A head may have been replaced
> > by the previous owner. The system bled down correctly after my work,
> > there were no visible leaks. I currently don't see or smell any signs
> > of coolant leaks but will check hoses again. I've read that a leak can
> > be small enough to be an issue over long term but not easily seen.
> > However. The reason I suspect  coolant being burned is the relatively
> > sudden change in coolant level.
> >
> > Thanks
> >
> > Neil.
> >
> >
> >
> > --
> > 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>