Hi,

   Here is that mind boggling cooling system again. Please comment on it.
   
   For an 83 H2O boxer, its coolant spilled from the overflow tank to the
   refill tank. (Refill tank is the one located behind the license plate.)
   One week ago, I bleed the system and renewed the coolant. Now, it again
   spills to the refill tank. The refill tank is twice filled as it should
   be.

   I can only think of two culprits:
     (1). head gasket cracks. (It was replaced 6 years ago at a heffty price.)
          Then, exhaust gas is now getting into the cooling system.
     (2). some invisible cracks/leaks in the cooling system. Then, air is
          getting into the cooling system.

   How do I determine the true culprit? 

Regards,

James