I just discovered that my rear heater core has been shut off since I've had
the van (by the little lever on the side of it).  Since I've had the van,
I've drained/flushed coolant twice.  But since that heater core was shut, I
guess that the coolant there is old and nasty.  Any thoughts on whether the
coolant would have drained out of the core even with that valve shut?  Right
now I'm trying to see if I can just drain out the core by itself.  (I still
haven't run the van with the valve open.)

This is an 83 1.9l westy.

Thanks very much for any help,
Wes