Originally Posted by
tunaglove
The pressure increases inside engine bay when the fan runs closing the flaps. without the flaps hot air would be pushed forward through these vents back to the front of the radiator.
That's certainly an interesting theory. Fantastical in fact. Unfortunately the scenario you imagine simply can't happen. The engine bay would have to be sealed much, much, much tighter for this theory to work. It is not sealed that well.
