my '88 has a "bleeder screw" which is a knob on top of the thermo housing. In
the Bentley book, it says to open this knob by turning counter clockwise
before and during filling the cooling system. Well, at no time during the
process did I see any coolant escape from this bleeder, so what is it's
function, and should coolant escape from here in a properly air-purged system?