Reply to "Replaced radiator, now the engine is running hotter during stop and go driving"

Is it possible for you to fit pusher fans in front of the radiator say 6 inches away ?



For the same size and power a pusher fan will move more air through the radiator than what a draw through fan will and they do not need a elaborate fan shroud like draw through fans do, just a basic housing around each fan.

In fact push through fans work best spaced away from the radiator so the air moved by the fan can induce a flow in the surrounding air so that more air than what is actually being displaced by the fan is pushed back towards the radiator.

It is kind of a multiplying effect. This effect does not occur with draw through fans and if there is the slightest amount of air leakage past the shroud of a draw through setup the amount moving through the radiator will be less than the fan displacement.

Fans push air much better than they can draw air. You can test this with a household fan. If you place your hand in front of the fan you can feel a strong flow of air, but if you place your hand the same distance behind the fan the airflow will be much weaker. This is the effect of the airflow itself inducing even further airflow in the surrounding air on the discharge side.

This is why it feels like you have good airflow on the discharge side of your draw through fans but there is poor flow on the inlet side (front of the radiator) the air flow on the outlet side is inducing further airflow from whatever air is nearby (not necessarily through air leaking or bypassing the shroud) and not from drawing all that air through the radiator core.

I have a big 16" draw though fan on my radiator and my engine gets hot in traffic. But counter intuitively the car runs cooler in stop and go traffic when i have the air conditioner on because the a/c switches on two push through fans in front of the condenser and even though the a/c dumps tons of hot air in front of the radiator the extra draft induced by their discharge is more effective at cooling the engine than the big 16" draw through fan.