If engine still turns then it is (as alredy mentioned) most probably "just" a leak. If not a hose, then rubber head joints are most likely culprits as these are prone to fail @ milages over 60k. (blue/green gunge on joint is normal symptom). They sometimes just leak a bit for avery long time before finally failing big time. If you are very careful (& have a good set of tools!) it is possible to change these joints with engine in situ. (Must be carefull to remove only the head & not disturb the pots/bottom oil O rings)
Early 1.9's were prone to broken head studs/water leaks. If that has happened then it will be easier/cheaper getting another engine.
On 2.1's the LH metal water manifold is another weak point & prone to rust spots (I'm on third one on my Syncro).
Regards
Simon H
