On Sat, 14 Jan 1995, J. Meade wrote:

> Alistair,
> 
> It's not pressurized?  It darned sure blew back in my face adn gave me 
> some nasty burns when I foolishly unscrewed the cap once.  I'm talking 
> about the cap on the coolant reservoir.  The one with the bleed hose that 
> leads back to the overflow tank.  I'd assume it overflowed only over a 
> certain pressure.  Now I'm going to have to look it all up so I know what 
> I'm talking about.
> 

Jim, when I suggested pressurizing the system it was to purge any air and
check for leaks.
This is my idea...

Modify a spare resevoir cap to accept a hose from an old bug windshield
wiper fluid resevoir. You can pump those things up to 3 bar with a bike
pump, supplying pressure and fluid. Raise front end of van, loosen rad
bleeder and attach a hose, the other end of which is in a bottle with some
coolant. Run engine until thermostat open (coolant resevoir cap off),
then attach modified cap, pump up windshield wiper resevoir to 2-3 bar. 
If my idea works, then fluid/air should be spitting out of bleeder valve,
and any lost coolant will be made up by coolant from the windshield wiper
resevoir. 
If you close the rad bleeder valve then you can pressurize your whole
system to 2-3 bar and discover any weak connections, hoses etc.

Warning, this is a Sunday morning, drinking coffee, thought experiment. I
haven't tried this (although my mechanic pressurizes vanagon cooling
systems to bleed them, I haven't seen his setup), but it sound feasible.

Alistair