A system and method for the early detection of connecting rod bearing failures in pump power ends using temperature measurements is provided. The system may include a housing enclosing the pump power end, and a crankshaft, connecting rod, and crosshead all disposed within the housing, with the connecting rod coupled between the crankshaft and the crosshead. The system also includes a temperature sensor assembly at least partially disposed on the housing. The temperature sensor assembly is communicatively coupled to a controller located outside the housing, and the temperature sensor assembly is positioned such that the temperature sensor assembly detects a temperature of the connecting rod or the crosshead. A controller may read, store, and monitor temperature data received from the temperature sensor, and output an alert to an operator or shut down the pump upon detecting a temperature that exceeds a predetermined threshold.