In the past years many research efforts on turbocharger heat transfer have been performed, however, there are not enough investigations on unsteady condition of turbocharger. One of the unsteady condition is heat soak test. In this test, engine runs at maximum power until all temperatures are stabilized, then the engine stops suddenly. After the engine has been shut down, heat stored in the turbine housing soaks back into the bearing housing of the turbocharger. This heat can potentially destroy the bearing system and the oil-sealing piston rings. The aim of the paper is to investigate the effect of turbocharger temperature distribution in heat soak test and considering effect of electrical water pump on temperature distribution. Experimental investigation has been performed on gasoline engine turbocharger, which several thermocouples have been used on accessible surfaces of the turbocharger. Turbine, compressor and bearing housings temperature have been measured inside engine test cell. Moreover, temperature, pressure and flow rates of oil, water and air have been measured. Results of engine heat soak test with original cooling circuit, show that bearing housing temperature increases 60°C after engine shutdown and maximum temperature reaches 220°C. However, using electrical water pump after engine shutdown causes only 10°C incensement of bearing housing temperature.