1)The radiator's fans are backwards here, and as things currently are, you have an all exhaust airflow.
Flip the radiator fans.
2)Is there enough room in the chassis to allow you to turn the radiator 180 degrees to where the tubing enters from the bottom?
If not, disregard, and instead do the following:
-Remove the screws securing the radiator to the chassis.
-Turn the PC on.
-While it is on, move the radiator around so as to relocate the air pockets; the idea is to try and trap them in the radiator - which is what the tubing down position does with less effort.
-Then you can turn the PC off and proceed to secure the radiator back inside