[Jamo]

I agree with Patrick...not the pusher fans. Mine are off at speed, and even with the slight drag of being coupled to the motors, it doesn't stop airflow. If pusher fans are having that much of an effect...then you have troubles elsewhere.

Tom's suggestions regarding the pulleys seems to fit your recent fitment changes the best. The water isn't moving the heat out of the block.

Assuming no air bubble in the system.