MLG EXPERIENCES SMOKE AND EICAS WARNING AND FINALLY DIVERTS TO ALTERNATE ARPT. MEL CONSIDERATIONS ACTIVATED AND FLT CONTINUES TO DEST ARPT WHERE SOME SYMPTOMS ARE STILL EVIDENT. ACFT DIAGNOSED WITH MAINT DISCREPANCY OF LEAKING OIL FROM APU.

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FLT DEPARTED MSP 43 MINS LATE. ACFT; AN MLG; CAME FROM HANGAR WHERE APU HAD JUST BEEN REPLACED DUE TO PREVIOUS COMPLAINTS OF FUMES IN ACFT. SHORTLY AFTER TKOF; COCKPIT CREW NOTICED UNIDENTIFIABLE ODOR. WE CONSIDERED COOKING FOOD; HOT PACKS; AND OIL FUMES IN DUCTING (DUE TO ACFT HISTORY). SYS WERE NORMAL AND ODOR SEEMED TO DISSIPATE. CLBING THROUGH FL240 WE GOT A LAVATORY SMOKE WARNING AND ECAM MESSAGE. THE LEAD FLT ATTENDANT RPTED THAT THERE WERE SOME FUMES IN THE CABIN BUT NO SMOKE OR FIRE. WE FOLLOWED OUR COM PROCS AND THE COPLT WENT BACK TO VISUALLY CHK THE LAVATORY. WE LEVELED FL260. THE WARNING QUICKLY CLRED ITSELF AND THE STATUS PAGE READ 'NORMAL.' THE FLT ATTENDANTS AND COPLT FELT THAT THE AIR WAS CLRING. WE DECIDED THAT THE RECENT APU CHANGE WAS RESPONSIBLE FOR THE SMELL AND CONTINUED TO DTW. WE RECEIVED A SECOND LAVATORY SMOKE WARNING AFTER REACHING CRUISE ALT. THE FLT ATTENDANT RPTED THAT THE SMELL WAS BECOMING NOXIOUS AND IRRITATING. WE REQUESTED CLRNC TO MKE; 70 MI TO OUR E. IN CHKING THE SYS; WE FOUND THE L TO BE RUNNING SIGNIFICANTLY HOTTER THAN THE R PACK (ALTHOUGH STILL IN THE NORMAL RANGE) AND DECIDED TO TURN IT OFF. THE ODOR AGAIN SEEMED TO DISSIPATE; HOWEVER; AFTER DISCUSSING THE SITUATION WITH DISPATCH AND MAINT CTL; DIVERTING TO MKE SEEMED TO BE THE MOST PRUDENT COURSE OF ACTION. AN UNEVENTFUL APCH AND LNDG WERE MADE IN MKE. MKE MAINT INSPECTED THE ASSOCIATED SYS AND DECIDED THAT THE L PACK WAS THE CAUSE OF THE FUMES. THE PACK WAS MEL'D AND PLACARDED. WE DEPARTED TO DTW WITH A SINGLE PACK OPERATING. THE FLT WAS ROUTINE WITH ONLY A SLIGHT RESIDUAL ODOR IN THE COCKPIT. UPON ARR AT THE GATE; THE FLT ATTENDANTS RPTED THAT THE FUMES WERE STILL PRESENT AND IRRITATING IN THE CABIN. MAINT WAS INFORMED THAT THE PROBLEM STILL EXISTED. AN OIL LEAK WAS FOUND IN THE APU AND THE ACFT WAS TOWED TO THE HANGAR FOR REPAIR.