A venting plug assembly for sealing a coolant channel and venting air therefrom is disclosed. The coolant channel defines an open portion to receive the venting plug assembly. The venting plug assembly includes an outer sealing element with an annular portion configured for sealing engagement with the open portion of the coolant channel. The venting assembly further includes an inner sealing element configured for sealing engagement with the annular portion of the outer sealing element. The inner sealing element is configured to move relative to the annular portion of the outer sealing element to allow air to vent from the coolant channel through the outer sealing element.