Abstract: A valve device for draining liquids from a tank and, more particularly, a valve device for draining lubricating oil from an engine crankcase. The valve of the invention is characterized in having a generally tubular valve casing, containing a valve element spring-biased into closed position, which is permanently threaded into an opening in a tank. To open the valve and drain the contents of the tank, a pressing sleeve is inserted into the valve casing, this pressing sleeve serving to engage the valve element and unseat it as the sleeve advances into the casing by turning a cap nut which threads onto the casing, whereupon liquid will flow through the now-open valve and the pressing sleeve to a sump or the like.