How to install a centrifugal pump
 

A lot of us are installing some kind of electric coolant pumps and what not so we might as well do it correctly.

Pump orientation is very important.
The "best" and "good" orientations or anywhere in between them let any air bubbles out of the pump when it is stopped or when it first starts up. The Orientations labeled "no" do not allow air out of the pump.

Suction head versus suction lift are very important.
All the 12v centrifugal pumps I have read the instructions for warn against running them dry for any amount of time. The seals have to stay wetted to keep from burning up.
Suction lift represented by the pump above the level of the reservoir of green coolant is not recommended by pretty much all automotive use pump makers.
The eye of the pump should at the very highest should be level with the fluid to be pumped. Ideally the pump should be well below the liquid level.

http://ecomodder.com/forum/attachmen...1&d=1456781301

thanks for the info

It's not just the seals. Running dry will cause the motor to spin too fast and also heat up. This causes excessive wear on motor brushes and risks burning out the whole motor.