Ok, I have heard that removing your engine driven mechanical fan and replacing it with an electric one will increase your fuel mileage. Now, with this said, will an electric fan cause more drag at speed because it is not turning off if it is trying to keep the engine cool? (thermostat controlled). I know the mechanical fan has a hydraulic thermostatic clutch, so at speed it should be literally free-wheeling. Also, if you are wheeling, what is better? or both?
Rob

 

The claim is that mechanical fans rob more power from the engine than do electric fans, and in doing so lower the mpg also. Probably true. Most new cars are going the way of electric motor driven cooling fans. I do know that the drag racing community use electric fans to shave a bit off their ETs, so the theory must be true as far as robbing power. Will your Montero mpg benefit from the swap? Don't Know! I have electric fans on both Corvettes and the only time the fans are needed is when you are not moving (in traffic) and insufficient air flow is getting through the radiator. At speed the natural air flow cools the engine without the fan running at all.