What was found
CRUISING, FL340. ODOR IN FLT DECK. SMELLED LIKE A WET DOG, MUSTY TOWEL, OR DIRTY DIAPER. GOT STRONGER. OPENED C/P DOOR & SAW A CLOUD IN BACK. BURNING IN NOSTRILS. PUT ON OXY MASKS. DIDN`T RECEIVE FIRE - SMOKE WARNINGS. DIVERTED, COULDN`T DETERMINE SOURCE. EMERGENCY DECLARED. MX CHANGED COALESCER BAGS. BAGS DIRTY. RAN ENGS PER JRH & ABLE TO DUP CLOUD IN CABIN & COCKPIT. AFTER HI PWR ENG RUNS PER JRH & BURNOUT OF AIR COOLING SYS IAW MM, COALESCER BAGS CHANGED AGAIN. BAGS CLEAN & NO CONTAMINATION. AFTER ENG RUNS, & HI PWR, PRESSURIZING ACFT, UNABLE TO DUPLICATE CLOUD & ODOR. HYD CHK VALVES CHANGED IAW MM. DUCTS INSPECTED IAW MM. NO CONTAMINATION. ACFT SCHEDULED FOR A FUNCT CHK FLT. A/C OK FOR SERVICE.