>I've just replaced both sensors by the thermostat housing and about 3-4
>cups of antifreeze came out. do i need to bleed the whole system?

Why not?  Anytime I service the cooling system on a Vanagon I do the
bleed thing.  To be sure it is a PITA but only takes an hour or less to
setup, bleed, and put your supplies away.  It is cheap insurance, why
take chances?

Tony

Anthony L. Mourkas
Hampden, Maine, USA
1984 Vanagon Westfalia
1991 Jetta Eco Diesel