The intent of this study was to investigate experimentally the root cause of torque loss in a die-cast aluminum threaded fastener joint that is used to assemble an engine mount to the front cover of an automotive engine. The primary goal was to develop a practical experimental method to characterize threaded fastener joints in situ. Using installation torque measurements, hardness test results, and a DC nut runner, joint attributes were measured, and the data was evaluated. This investigation demonstrated that the incompatibility of the mechanical properties at the interface of the housing and fastener resulted in significant torque loss. Further investigations are planned to study cost effective design modifications.