The present invention is a method and apparatus for unidirectional coolant flow control unit for pressurized cooling systems. The invention comprises a valve on a coolant flow control unit. The valve remains in the open position during normal function of the coolant flow control unit. If the coolant flow control unit fails, the valve closes. Thus, the cooling system performs better than prior art cooling systems in the event of a failure of one or more coolant flow control units. In one embodiment, multiple improved coolant flow control units can be implemented wherein a flow of coolant enters one side of the system and exits the other side. In the even of a failure, the closure of the valve is caused by the shifting pressure within the system, which forestalls the cooling problems associated with prior art redundant coolant control flow systems.