A system for controlling airflow through a syphon tube associated with a vehicle cowl airbox disposed within an engine compartment associated with a vehicle may include a drain valve disposed on one of a first open end and a second open end associated with a hollow tubular portion of the syphon tube. The drain valve may include a connecting portion configured to be received by a portion of a first passageway defined by a divider extending between the first open end and the second open end. The drain valve may further include a flap attached to the connecting portion, the flap configured to, in response to the vehicle cowl airbox being drained through a second passageway defined by the divider, allow air to flow through the first passageway and, in response to a negative pressure within the vehicle cowl airbox, prevent air from being drawn into the syphon tube.