A sealant-filled enclosure assembly for environmentally protecting a connection includes a housing, a mass of sealant and a sealant valve mechanism. The housing includes a main cavity to receive the connection. The mass of sealant is disposed in the main cavity. The sealant valve mechanism includes an overflow chamber and a gate member between the main cavity and the overflow chamber. The gate member is selectively positionable in each of a closed position, wherein the gate member substantially prevents displacement of the sealant from the main cavity to the overflow chamber, and an open position, wherein the gate member permits displacement of the sealant from the main cavity to the overflow chamber.