Bleed per Bentley manual at 2000rpm with front raised and all heater open and on full�for at least a few minutes to rule out air being trapped.
If it still builds pressure, you have an internal head gasket failure, very common.
A leak down test will confirm that.

best of luck.

dylan

________________________________
From: matthew <Mattmoosh2000@COMCAST.NET>
To: vanagon@GERRY.VANAGON.COM
Sent: Thu, December 10, 2009 3:25:36 PM
Subject: overheating vanagon 86

I bleed the air out of the system, I think I just got it all out, but there
is not much pressure when I open the radiator bleeder.

It was bubbleing slightly, but also constanly until I drove it a bit. I only
bled them for 40 seconds after I drove.

When it gets air the expansion tank builds a lot of pressure. The stream
pumping in seems like it could be more constant. but if the bubbles are
coming out of the radiator bleeder it could be the radiator? I am a novice,
and a pump seems like it could pump air to the radiator. Does it sound like
it could leak air in? it doesn't seem to be doing it right after I drove,
but the expansion tank was at the min until I unscrewed the cap, then it
quickly filled.

P.S. I don't know where all the bubbles could be, or what the bleeder near
the thermostat does.