B737-300 CREW HAD ENG OVERHEAT WARNINGS FROM BOTH A AND B LOOP SENSORS.

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DEPARTED AT XA00; OFF AT XA12 CST. APPROX 75 NM FROM ORIGINAL CITY DURING DEP WITH CLB PWR. AT FL250; #2 ENG OVERHEAT LIGHT FLICKERED ON 3-4 TIMES; SEVERAL TIMES MORE DURING REFS TO QRH. QRH ENG OVERHEAT ACTIONS WERE TAKEN WITH OVERHEAT LIGHT EXTINGUISHED; NEVER TO ILLUMINATE AGAIN EXCEPT DURING SYS TESTS. AFTER SUCCESSFUL AND NORMAL OVERHEAT/FIRE SYS TEST BEING PERFORMED; SELECTIVELY PLACED #2 FIRE LOOP SWITCH FROM NORMAL LOOP A AND B. FAULT LIGHT CAME ON WITH LOOP A ONLY SELECTED WITH ADDITIONAL REFS TO QRH. CONTACTED MAINT FOR ADDITIONAL SUGGESTIONS OF SYS CHKS AND ANY RECOMMENDATIONS OF CORRECTIVE ACTIONS. NO ASSISTANCE GIVEN EXCEPT ADHERE TO QRH FAULT LIGHT. FLT ATTENDANTS AND PAX ADVISED OF TURN BACK DUE TO 'PROB WITH ENG MAINT MONITORING SYS AND NOT BEING REPAIRABLE IN DEST CITY.' CONTACTED ATC FOR TURN BACK AND RECOVERY WITH IMMEDIATE DSCNT AND ARR CONDITION WITH CTR AND ARR. NO EMER DECLARED WITH ATC. ADVISED OF RETURNING FOR MAINT ITEMS ONLY. DUE TO TIME COMPRESSION; EXPLANATION TO FLT ATTENDANTS; EXTENSIVE ATC COORD; AND ROUTING; AND ADVISING 3 DIFFERENT CTLRS OF NATURE OF PROBS; DISPATCH WAS NOT ADVISED. RETURN WAS UNEVENTFUL WITH REDUCED THRUST AS REQUIRED ON #2 ENG FOR NORMAL FLAP 30 DEG APCH. LNDG RWY 25L WITH ARR AT GATE AT XA55 CST. CONTACT WAS MADE WITH DISPATCH AND MAINT CTL IMMEDIATELY UPON ARR AT GATE. APOLOGIES AND EXPLANATIONS WERE MADE TO DISPATCH FOR NON-CONTACT. ACFT HAD HISTORY OF SIMILAR PROB WITH LAST EVENT ON SEP/THUR/02; WHICH WAS 2 DAYS PRIOR TO FIRST PAGE IN LOGBOOK. MAINT CTL AGREED WITH CREW ACTIONS; CHKING OF TEST SYS FOR FAULT LIGHT; AND TURN BACK FOR CORRECTIVE REPAIRS. ASSISTANT CHIEF WAS CONTACTED WITHIN 15 MINS OF ARR WITH FULL EXPLANATIONS OF EVENTS. UPON ADVICE FROM CHIEF PLT; ASAP ACTIONS WERE INITIATED WITH WRITTEN RPTS TO FOLLOW. CREW AND PAX WERE XFERRED TO SECOND ACFT WITHIN 1 1/2 HRS OF ARR FOR UNEVENTFUL FLT. SUPPLEMENTAL INFO FROM ACN 560560: FLT DEPARTED. I WAS PF. DURING CLBOUT; PASSING APPROX 25000 FT; WE EXPERIENCED AN INTERMITTENT #2 ENG OVERHEAT LIGHT. WE RETARDED THE THRUST LEVER WITHOUT RESULT. THE OVERHEAT LIGHT CONTINUED TO FLICKER BUT NEVER ILLUMINATED STEADILY. THE CAPT ATTEMPTING TO TROUBLESHOOT SELECTED 'A' LOOP AND GOT A 'FAULT' LIGHT; FLICKERING CEASED. HE THEN SELECTED 'B' LOOP; AND GOT AN INTERMITTENT OVERHEAT ONCE AGAIN. AFTER A VERY BRIEF CONVERSATION WITH MAINT; HE ELECTED TO RETURN TO ORIGINAL CITY. THE SUBSEQUENT APCH AND LNDG WERE UNEVENTFUL; NO FURTHER PROBS NOTED. I FEEL WE HANDLED THE SIT WELL. THE CAPT RAN THE APPROPRIATE CHKLISTS BEFORE ATTEMPTING TO FIX THE PROB. HE LET THE QRH DO ITS JOB IN TROUBLESHOOTING AND THEN MADE THE DECISION TO RETURN. I WAS FLYING AND CONTINUED TO DO SO WHILE HE SORTED THINGS OUT. WE EACH FULFILLED OUR ROLES AND BROUGHT THE SIT TO A SUCCESSFUL END.