One problem related to engine head gasket failure has been reported for the 2010 Ford Flex. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2010 Ford Flex based on all problems reported for the 2010 Flex.
Total motor failure when driving! transmission frequently slips. Motor had to be replaced. When pressure exhaust for ecoboost is redirected to cylinder 3 and 5 the head gasket fails allowing water to enter the head of motor which them steam fries the cylinders. This is very common in the 2010 Flex with ecbiost and need to be recalled ASAP! motors up to 100,000. Mine had 74000 when failure occurred.