A sealing assembly hinders or prevents air or other fluid from seeping between various components of a medical device by use of a liquid seal. An infusion port is for introducing a sealing liquid to immerse a flood space between a liner that surrounds a torque tube and/or within the torque tube, thereby creating a liquid seal around the torque tube and lubricating the torque tube. The length of the liner and the cross sectional space of the flood space are adjusted to control flow rate. An aspiration port may force suction pressure into a lumen extending along the length of the medical device in a distal direction. The liquid seal also prevents diluting of the suction pressure by stopping ingress of air.