One problem related to radiator has been reported for the 2011 Ford Flex. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 Ford Flex based on all problems reported for the 2011 Flex.
While accelerating from a stop with the ecoboost system , the car will almost stall, then speed up with out your foot on the pedal. It blows black smoke and then it will be fine. This has happened on and off for the past several months, the car had an extended warranty in which this showed up. While this was going on I have had to replace the power transfer unit because it locked up, then the car would only work in front wheel drive, have had nothing but trouble since the car radiator fan system burned up and they replaced. They have re-flashed modules after they could not figure out what was happening, however it still does it. I am worried as the car has speed up to 2000 rpm while driving and stayed there with out the gas pedal being pressed.