<p>The automotive industry is increasingly focused on sustainable manufacturing processes, particularly in the production of internal combustion engine (ICE) components. Recent advancements have found 3D-printed inorganic bonded sand cores in the manufacturing process of ICEs, which are critical for minimizing emissions. The 3D-printed sand cores for the high-volume production of cylinder heads show a large distortion in thin-walled areas in light metal casting applications. This study investigates the thermal stability and creep behavior of these 3D-printed sand cores. To decrease the development costs of future cast parts using 3D-printed sand cores, a simulation model to predict these distortions is validated in this work. Stress rupture tests of 3D-printed bending bars are conducted and the distortion over time measured and compared to bending bars manufactured by the core shooting process. Using these data for advanced simulation models, including the Drucker–Prager–Cap model for plasticity and a rheological model for viscoplasticity, are validated to account for the distortion during the casting process. The creep curves of inorganically bonded sand don’t show the typical creep behavior of, e.g., metals, due to the deformation taking place rapidly in a short amount of time and a sudden stop when the maximum deformation is reached. The findings highlight the necessity for improved material models to accurately predict the performance of these innovative cores under varying thermal conditions, due to new discovered dependencies of creep of 3D-printed inorganic sand cores.</p>