What was found
DURING TAKE-OFF AROUND 600' DURING GEAR RETRACTION WE GOT A HYDRAULIC/ELECTRICAL ODOR IN THE CABIN. AROUND 1500' THE ODOR CONTINUED TO GET STRONGER. LEVELED OFF AT 4000' STARTED A RETURN BACK INTO KDAL. THE ODOR STARTED TO DISSIPATE A LITTLE, THE FLIGHT ATTENDANT NOTICED THE ODOR IMMEDIATELY AFTER TAKE-OFF. ON THE APPROACH BACK INTO KDAL LOWERING THE LANDING GEAR CAUSED THE SMELL TO COME BACK. ONCE WE LANDED WE CHECKED THE ELECTRICAL AND HYDRAULIC SYNATIC PAGES. THE ELECTRICAL PAGE LOOKED NORMAL. THE NR 2 HYDRAULIC TEMP WAS AROUND 67 DEGREES. R & R THE LT & RT WATER SEPARATOR COALESCER BAGS WITH NEW COALESCER BAGS IAW CL650 AMM 21-51-13-000-801 / 21-51-13-400-801. PERFORMED APU/ENGINE RUN AND OPERATED AIR CONDITIONING SYSTEM AMM 21-00-00-862-803/-804. HI-POWER RUN WAS 10 MIN LONG WITH PERIOD OF 5 MIN AT IDLE, FOLLOWED BY SECOND 10 MIN HI-POWER RUN. NO ODOR NOTICED IN COCKPIT OR CABIN.