A pump, in particular for a fluid circuit in a vehicle, for example a coolant pump with a multi-part housing which has a pump chamber and a motor chamber, wherein an impeller is disposed in the pump chamber which is driven by a rotor arranged in the motor chamber, and wherein the rotor has a rotor shaft and a rotor body through which the rotor shaft is guided, wherein the rotor has through holes, which interconnect a space of the motor chamber on a first side of the rotor and a space of the motor chamber on a second side of the rotor.