check your local yellow pages for Radiator Repair shops, ask if they have a dip tank, 
they can power flush
pressure test
and if it's a diesel copper core possibly resolder repairs
a good shop should be able to recore it cheaper then a new one.. copper or aluminum.

Dan.

Date:    Wed, 8 Oct 2003 15:52:12 -0700
From:    Felder <felder@KNOLOGY.NET>
Subject: Latest overheating inquiry--radiator needed?

I stopped by my VW shop at lunch to pick up a thermostat and 0-ring. I
told them what was happening... hot coolant in the rear, cool radiator,
but water pump working well enough to pump coolant to the top of the
tank, sitting level.

The mechanic said it was probably a stopped up radiator, for which
there is no cure but to replace the radiator. Anybody have experience
with this? Does this sound reasonable, and if it does (symptomatically,
it sounds reasonable, but I mean can they not be cleared?) who has a
used radiator (single sensor/switch, low driver's side)?

thanks,

Jim