OK, so I finally got up enough energy to replace the coolant 
in my 85 Vanagon and have the following question about the 
air-purging procedure.

I have read Bentley's procedures for jacking up the front and
removing the bleed screw on the radiator, etc.  He also states
that the bleeder valve on the coolant hoses in the engine 
compartment should be opened.  However when I do this nothing 
comes out.

Is my bleeder valve clogged, or does this valve just open a 
passage to that little 1/4-inch hose that runs from the bleeder 
assembly to the adjacent steel coolant pipe?

If anyone who has done this knows the answer, I would appreciate
a reply.  I don't know whether or not to replace my bleeder 
assembly.  TIA!