What was found
ENGINE WAS 'REMANUFACTURED' BY LYCOMING, DATED 12-13-90. REMOVAL OF NR 3 CYLINDER TO INVESTIGATE AN OIL FOULING PROBLEM REVEALED A BROKEN PISTON. PISTON SKIRT HAD BROKEN OFF ON THRUST SIDE (TOP) OF PISTON BETWEEN THE PISTON PIN BOSSES AND UP TO OIL CONTROL RING GROOVE. PISTON APPEARS TO HAVE BEEN CRACKED BETWEEN THE 2 OIL CONTROL RING GROOVE OIL DRAIN HOLES FOR SOME TIME BEFORE BREAKING. ENGINE RAN FINE WITH NO INDICATIONS OF A SERIOUS PROBLEM EXCEPT FOR OIL FOULING OF THE BOTTOM SPARK PLUG. A COMPRESSION CHECK DONE HOT JUST BEFORE CYLINDER REMOVAL SHOWED 76/80 PSI.