One problem related to engine failure has been reported for the 2013 Ford Flex. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2013 Ford Flex based on all problems reported for the 2013 Flex.
While traveling at 55 mph, on cruise control, the engine began to knock and then the car lurched forward twice and began to shake pretty bad. I pulled off the road and called the dealership. After holding up the cell phone to the engine, I was told to "turn that engine off now!". The car was towed to the dealership and I was later told there was a catastrophic engine failure due to an cylinder within the internal piston that broke free and put a whole in the engine block, requiring the engine to be replaced. The service manager gave me the mangled cylinder and stated he thought the ball bearings had failed and caused the cylinder to wreak havoc with the engine. After seeing the piece that broke off. I feel that we were very lucky it did not come through into the passenger compartment; it could have caused a serious injury, if it had. Ford has agreed to replace the entire engine under the extended warranty, saying this type of failure only happens "1 in a million". I do not have any confidence that the same type of engine failure would not happen again if the ball bearings and or cylinder are inferior. I have pictures available if needed.