how do i fix air block in radiator on vw passat?

if the coolant level in your header tank shows correct level then it could be your thermostat is on its way out, take it off and put into a pan of boiling water, if it opens, its ok, if it remains closed or only partly opens then it needs to be changed.when filled with coolant, take it for a run, and this should take out any air pockets, and re-check coolant level.

hope it helps
August 2010