A fuel cell stack configuration and method of removing gas from the coolant flow path within a fuel cell stack is provided. The fuel cell stack has an internal vent passageway that communicates with the coolant supply header to enable gas entrapped therein to be vented from the fuel cell stack. The vent passageway can be formed by a plurality of apertures in the components that comprise the fuel cell stack and run parallel and adjacent to the coolant supply header. Alternatively, a vent line can be connected to the coolant supply header with a valve therein to selectively vent gas from the coolant supply header.