Nowadays, the world faces tough challenges related to climate change that are leading to an energy transition towards clean energy sources. In the automobile sector, electric vehicles are becoming more popular and affordable. Electrical machines are expected to be increasingly more efficient and have greater power density, and therefore the implementation of effective cooling systems is crucial. The objective of this paper is to investigate a novel cooling system to be implemented at the end-winding of a permanent magnet synchronous motor. A thermal model is implemented in the commercial software COMSOL Multiphysics, which is validated through the data experimentally obtained from workbench tests in the motor. In the initial phase, experimental tests of the blocked rotor with alternating current were performed until steady state was reached. In this way, the power losses distributed by the motor components and the temperature evolution at points of interest (winding, stator, fin housing) were obtained. A thermal model was developed and calibrated using these data, through a sensitivity analysis of the critical thermal parameters of the motor, to reduce the difference between the predicted temperatures and the measured ones. Then, a parametric design of the cooling system was carried out, considering mechanical and thermal requirements. The performance of each configuration was analysed through numerical simulations. The final geometry was determined through the best compromise between the pressure drop and the maximum motor temperature. The results demonstrate that the proposed cooling method greatly reduces the maximum temperature in the motor, from more than 75°C to less than 30°C. Moreover, the cooling method remains effective even if the heat losses increase by a factor of six.