I have a 3rd gen with a rebuilt engine from Jan. of this year. Upon starting it one morning, I got the "Add Coolant" light. Turns out the overflow was empty also. Suspecting an o-ring failure, I checked for bubbles in the coolant while the car is running and, lucky me, they are there.

As a double check, I had the cooling system pressure tested. It turned out ok, no pressure loss. Then I had the block test done (checking for fuel fumes in the coolant), and it came back clean.

So now I have two tests that say the engine is fine, and one that says it needs to be rebuilt. Anyone know what might be going on?