[C320-list] Coolant mixing with raw water

[Dave Hupe]

 The more I hear about your dilemma, it sounds most like the tank is the problem.  If the exchanger tube were cracked, I don't see coolant getting into the tube once the coolant level  in the tank dropped below the tube bottom.  I would think you still would see (although hard to see) some coolant in the low portion of the tank.  However, you are saying you've repeatedly filled the tank and found it dry. My concern is that coolant (when the engine is not running and you've refilled the tank) is slowly collecting in the exhaust ports (this is where the tank connects to the engine) and gravity draining back into the engine and/or the exhaust elbow.  
Dave Hupe
1994 Cat320 (#32) "Mayan Sun"
Holland, MI