Engine Cooling problem
1999 Subaru Forester 4 cyl All Wheel Drive Automatic 150000 miles

Engine ran hot. Replaced block, etc. Ran hot again. Replaced radiator, sensors, water pump, many other things. Mechanic says a rarely diagnosed block liner has small crack that does not show up until engine running hot. By then, pressure has sucked up coolant into engine and lose cooling effects of radiator. I trust my mechanic, but want to check it out anyway. They are even writing off second repair, so I have no reason to disbelieve. ??? Would have ot replace engine, but car too old???