i have noticed w/ the electric fan setups you can either push or pull the air thru the radiator.what are the +'s or -'s of this?  what one is best? thanks  

Fans set up to pull through the radiator are more efficient than those set up to push through a radiator. Often times you will see a fan's cfm rating and if you read the fine print that is for in a pulling scenario. Sometimes they list the revised cfm for the pushing configuration.

Also, the pulling mode usually allows for more mounting room since the vehicle usually has room left over from the old mechanical fan and shroud, where as in a pushing mode you have to deal with grille supports, valences, headlight brackets, and so forth.

HTH...
Mark  

one more thing...   with electric cooling fans...  ram air through the radiator is needed...

the area in front of the core support on some cars has factory rubber flaps to direct air through the radiator... when these get removed over the years... the air can go around  instead of through..  so it is lost for the purpose of cooling the motor..

on some models there were also rubber strips on top of the core support...  did the same thing...  

Things to remember about electric fans - the are typically rated in "free air" ,meaning zero restriction.  The radiator creates a pressure drop, which de-rates the fan.  Pusher vs puller also de-rates the fan capacity, as much as 30% or more.  An electric fan can become just like a round piece of plywood at highway speeds - this is why you'll see some OEM fan configurations with rubber flaps to bleed air out from behind the shroud.