B767-200 CREW HAD A STRONG 'GASOLINE TYPE' ODOR IN AN AFT ACFT LAVATORY.

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AFTER TKOF; FLT ATTENDANT #3 NOTICED A STRONG ODOR FROM AFT R-HAND LAVATORY AND ASKED ME TO VERIFY. I COULD NOT IDENT THE SMELL; BUT IT WAS STRONG. FLT ATTENDANT #3 THOUGHT IT SMELLED LIKE GASOLINE. I HAD TO AGREE; THAT WAS THE BEST DESCRIPTION. I THOROUGHLY CHKED THE LAVATORY. I CHKED THE WASTE BIN; AS MAYBE SOMETHING WAS DISCARDED ON A PREVIOUS FLT THAT HAD AN ODOR. NO ODOR. I FELT UNDER THE SINK. IT WAS DRY. I SEARCHED ALL COMPARTMENTS -- NOTHING. I RAN WATER INTO THE SINK; FLUSHED THE TOILET; AND CHKED THE OVERHEAD BIN AT 37 HJ -- NOTHING. IT WAS A MYSTERY. FLT ATTENDANT #1 CAME BACK AND RECHKED THE LAVATORY. THE ODOR WASN'T NOTICEABLE WHEN THE DOOR WAS CLOSED. LOCKING THE LAVATORY WAS DISCUSSED; BUT WE DIDN'T WANT THE FUMES TO BUILD UP. LEAVING THE DOOR OPEN WAS DISCUSSED; BUT THAT WOULD BRING THE FUMES INTO THE CABIN. SINCE THE CABIN AIR IS RECYCLED; WE DIDN'T THINK THAT WAS A GOOD IDEA. WE DIDN'T WANT PAX USING THE LAVATORY; AS WE DIDN'T KNOW IF THE ODOR WAS TOXIC; COMBUSTIBLE; OR BOTH. A NON-REVENUE CREW MEMBER JOINED OUR SEARCH AND RECHKED THE LAVATORY. OUR CREW MEMBERS CAN NO LONGER LEAVE THE COCKPIT. THEY MUST RELY TOTALLY ON OUR DESCRIPTION OF THINGS. BY THIS TIME; PAX AT ROW 36 COULD SMELL 'IT;' WHATEVER 'IT' WAS. FLT ATTENDANT #3 DIDN'T FEEL WELL; AND RUSHED TO THE AFT L-HAND LAVATORY. WE WANTED TO PREVENT A COSTLY UNSCHEDULED LNDG; BUT WE DIDN'T KNOW WHAT WE WERE BREATHING AND STILL HAD 4 HRS TO GO. THE CAPT OPTED TO LAND THE PLANE IN LAS. HE WOULD CUT ALL GALLEY PWR; ETC; FOR LNDG. FLT ATTENDANTS #2 AND #3; WHOSE JUMPSEATS ARE 3L AND 3R; OPTED TO REMOVE THE HALONS AND HAVE THEM AT THEIR JUMPSEATS FOR LNDG. WE LANDED NORMALLY AND PULLED INTO A GATE AT LAS. SOME FLT ATTENDANTS WONDERED WHY FIRE TRUCKS DIDN'T MEET THE FLT AND WHY WE WOULD PULL INTO A GATE? THE DECISIONS REST WITH THE COCKPIT. MECHS BOARDED THE PLANE IN LAS. THEY ALSO RECHKED THE LAVATORY; CEILING; AND CARGO. THE FUEL LINES WERE NOT IN THE AREA OF THE AFT LAVATORY. IT WAS A MYSTERY. THE LOGBOOK WAS THE LAST THING THEY CHKED. A LOG ENTRY HAD TO DO WITH THE AFT R-HAND LAVATORY DOOR BEING STICKY. IT WAS LUBRICATED. WHATEVER WAS USED TO 'LUBE' THE DOOR CAUSED THE ODOR. THE LUBRICANT WAS REMOVED. WHAT CAN WE LEARN? CHK THE LOGBOOK FIRST. KNOWING WHAT CAUSED THE ODOR WOULD HAVE MADE US FEEL SAFER. HOWEVER; THE ODOR WAS SO STRONG; FLT ATTENDANTS AND PAX WERE APT TO BE SICK; HAD WE NOT LANDED.