A shunt tank assembly for a cooling system is provided. The shunt tank assembly includes a vent tube, a shunt tank, and an inlet port provided on the shunt tank. The inlet port is in fluid communication with the vent tube. The shunt tank assembly also includes an insert disposed in the inlet port. The shunt tank assembly further includes a drop tube. The drop tube includes a plug portion having a first length and received within the insert. The drop tube includes a transition portion tapered with respect to the plug portion. The drop tube includes a tube portion extending from the transition portion and terminating with a chamfered end. The tube portion has a second length greater than the first length of the plug portion. The tube portion is bent such that the chamfered end is disposed below an average coolant level of the shunt tank.