Over the last two years my 2015 EL XLT 4WD has been randomly over heating mostly when towing up a steep mountain. I changed the thermostat and no change so I decided to change the water pump and discovered it had lost all but one of its impeller blades, I replaced it with an metal water pump from auto zone. I had to flush out the system to get the pieces. I like OE parts but in this case I do not trust motorcraft. Pretty amazing that it only over heated when under a very heavy load.