As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(LOG 7489532) ODOR ON TO ROLL TILL ABOUT 8000' STRONGER ODOR ON DESCENT AROUND 20,000' WENT AWAY AROUND 6000'. T/S PER B737 FIM 21-00-00-810-804, NEVER DID DETECT ANY ABNORMAL ODOR. HYD LEVEL WAS NORMAL, NO ENG OIL LKS NOTED. PER MCC REQUEST REPLACED EQUIPMENT COOLING FILTER (WAS VERY DIRTY) PER B737 AMM 21-27.