What was found
TPA - FLT 1648 - CLIMBING THROUGH 8,000 FEET OUT TPA, EN ROUTE TO PIT, CREW ADVISED THAT THE NR 1 ENGINE OVERHEAT LIGHT ILLUMINATED. POWER WAS REDUCED ON THE NR 1 ENGINE AND THE LIGHT EXTINGUISHED. FLIGHT RETURNED TO FIELD AT TPA AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE FOUND THE NR 1 ENGINE PRECOOLER CONTROL VALVE SENSOR AND 450 DEGREE THERMOSTAT O-RING BLOWN OUT. REMOVED AND REPLACED THE SENSOR AND THE THERMOSTAT. RAN NR 1 ENGINE TO POWER. OPS CHECK AND LEAK CHECK GOOD. (M)