As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ENGINE RECEIVED FOR CRANKCASE REPAIR. ON DISASSEMBLY THE TIP OF THE EXHAUST VALVE STEMS, ON 2 CYLINDERS, WERE FOUND TO BELOW THE VALVE KEEPERS. THE VALVE KEEPERS WERE FOUND DAMAGED AND THE EXHAUST ROCKER ARMS WERE FOUND SEVERELY WORN. AS THE CYLINDERS WERE NOT DISASSEMBLED IT COULD NOT BE DETERMINED IF THE VALVE STEMS HAD WORN OR IF THE VALVE KEEPERS WERE FAILING. THE 2 CYLINDERS WERE RETURNED TO THE MANUFACTURER FOR INVESTIGATION.