You start from a cold state and in an elevated right front corner
vehicle position. The reason is to allow the air (both in suspension
and in pockets of marginal hose bends and loops) to collect into
distinct moveable air pockets. Usually sitting overnight.
        You run @ 2000 rpm until it reaches sufficient temperature to
open the thermostat; it is at that point you will start to achieve
circulation in the system. That's when you get the best evacuation of
blocks of air and less foam from the bleeder valve.
        I fabricated a 'throttle stick' with a sharp point (nail) in
each end; one end on the gas peddle and the other on the under the
rim of the steering wheel; it works better than an assistant.
        This experience comes from touring 8000 km. with a blown
headgasket and bleeding the system each night.

                                David (dsl82westy)

Damon:
        I'm sure others will jump in with a more detailed check list,
but I would first run the van up a steep slope and then remove the
grill and bleed the air out of the system; keep adding coolant as it
draws down from the overflow tank.
        It works best if done from a cold state, allowing the air to
collect in the upper most corner of the radiator. I say do this
because if you do have air trapped, when it heats and expands, the
coolant is forced out. That won't cure anything, but in short order
it will tell you if the headgasket is gone again and the pistons are
pumping air into the coolant system.
        Also, I would replace the pressure cap, just on speculation;
I bought one that was defective or at least became defective very
soon. That cured the problem that time.
        Before that I had the cursed blown headgasket problem in my
1.9, '84 Westy.

Good Luck! and you have my heartfelt sympathy.

                                        David (dsl82westy)