This is tough since I am working at a distance (my son has the car approx. 200 miles away). There is a loud screeching noise, apparently from the engine compartment, on cold start up only. Shifting from Park to Reverse or Drive silences the sound (not instantly, more of a winding down sound). Since the sound is coming from the engine compartment and I recently renewed the belt, water pump, fan bearing bracket, idler pulley and tensioner pulley I don't suspect the belt drive. Could it be the AIR pump (NOTE: On this car it is not belt driven-it's apparently driven by an electric motor). When does the pump function? On a hot or warm start there is no problem.