[basjoos]

I've had both grill openings on my 97 Ford F150 4X4 totally blocked off since last spring and haven't had any overheating, even when pulling a loaded stock trailer in 80F temps. The only cooling air flow is through the 1/2" gap that runs the width of the trunk between the top of the bumper and the front sheet metal. I made the grill block of black duct tape, so I can easily remove part of it in the event of overheating. Truck grill intakes are sized for the largest available engine option towing the heaviest loads under the hottest summer temps and so are massive overkill for 99% of your driving.