What was found
SMELLED AN ODOR DURING TAKEOFF SIMILAR TO DEICING FLUID OR OIL IN THE AIR SYSTEM . NOT SIGNIFICANT UNTIL WE BEGAN DESCENT INTO IAD. DONNED OXYGEN AND DECLARED AN EMERGENCY FOR PRIORITY.STILL APPARENT WHEN MECHANICS BOARDED THE AIRCRAFT. T/S PERFORMED REMOVED AND REPLACED ALL 3 WATER COALESOR BAGS M/M 21-54-05-2. RAN ENGINES PER J.R.H. ISOLATED BLEED SYSTEM FOUND ODER COMING FROM NR 1 BLEED. OPEN NR 1 ENGINE COWL AND INSPECTED ENGINE FOR OIL LEAK AND CHECKED DUCTS NONE FOUND COWLING SECURED CLOSED. M/M 71-10-00-2-2. FUTHER T/S REQUIRE. PERFORMED AIR CONDITIONING PACK AND DISTRIBUTION DUCT CLEANING M/M 21-53-00-7 OPS CHECKED NORMAL.