Cast aluminum engine components are increasingly being used in the automobile industry. Due to high engine operating temperature, thermal fatigue during start-stop cycles is a very important design consideration. In this paper we will describe the application of newly developed analysis methods to analyze these complex problems. A user material subroutine for viscoplasticity stress analysis using the commercial FEA code ABAQUS has been developed. Stress and strain of engine heads during thermal cycle are thus analyzed and this code verified. The thermomechanical fatigue model developed by Neu and Sehitoglu, a damage accumulation model including fatigue, oxidation and fatigue damage, has been extended to three-dimensional state of stress by using the concept of critical planes. The enhanced damage model has been implemented in a FEA postprocessor for engine component life analysis. The predictions of thermal strains and fatigue life based on 3D FEA analysis are compared with measurements of engine component tests. Three different thermal loading cycles are considered. The thermal fatigue life predictions are within 30% error of actual component test data.