What was found
THE INSPECTION OF THE ENGINE REVEALED NR 3 EXHAUST STACK MOUNTING FLANGE AND SEVERAL OF THE CYLINDER STUDS WERE BROKEN. THE CARBURETOR AIR FILTER BOX WAS BLOWN OPEN AT THE SEAMS. IT APPEARS TO BE FROM ENGINE BACKFIRE. ALL CYLINDERS HAD NORMAL COMPRESSION AND THE ENGINE OIL SHOWED OBVIOUS SIGNS OF METALLIC PARTICLES. RUB MARKS WERE NOTICED ON THE RIGHT LOWER RUBBER MOUNTS. SUBMITTER STATED FROM EXCESSIVE VIBRATION, THE FACTS LEADS TO A STUCK CYLINDER EXHAUST VALVE.