Bongo Fury

my bongo had sat a while ,it started ok and so off i went for a 10 minute drive, i stopped heard a noise and opened the bonnet! i saw steam coming from over flow pipe down by front offside wheel. the header tank was empty...i openend the cap slowly......it had vacumed and let air in allowing water come back up to the header tank!!!!
The heater blowed cold until i opened cap then warm air and water system came back to normal!!!!
so its fine until starting from cold????? is this a brocken thermostat? if i change it will i lose all the water and end up having a nightmare bleeding system.........its fine once warm.....i hope its not dreaded head gasket!! no steam from exhaust..any help please!! Bryan

Firstly, DON'T DRIVE IT until its been checked out - further advice will be along very soon.

Could be any number of problems, including the stat, this thread may help you understand what you're dealing with - http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=35902 . You need to check the system thoroughly for leaks or evidence of staining from a pinhole leak, hoses swelling, staining around water pump showing a leak/failure there maybe? It's a difficult thing to remotely diagnose as the system has so many factors involved.
Either way, acquaint yourself with the bleed process ( it's not that complicated really, just time consuming & you have to understand what it is you're trying to do, ie open up all parts of the system) & as MM said don't risk driving it until you've got an idea of what you're dealing with.

As the expansion tank went low ... you MUST bleed it anyway....