Problem with 1991 Audi 100 (NF engine):
- no start; start after applying heater to engine;
- excessive spray of water from exhaust as engine warms;
- steam from exhaust manifold when warmed up but before engine got hot;
- replaced head gasket;
- engine starts; steam from exhaust manifold, then engine starts stalling and quits;
- applied air pressure (approx 5 psi continuous) to coolant overflow tank: coolant disappeared, crankcase oil level rose, no sign of external dripping;
- checked cylinder pressure: 130 – 140 psi.

Obviously, coolant somehow leaks into crankcase (and elsewhere?) when under some pressure.

Questions
- what might be the most likely place to look for the leak and how?
- if head is cracked, would a 1986 NF head fit?
- if block is cracked, would a 1986 NF engine fit?

Would appreciate advice