1997 buick lasabre, ok so here is the tough question. after running and getting hot i here a grinding and squealing noise. replaced the ac, tensionor, power steering pump and water pump. also just had the tranny rebuilt. ideas?

Did you replace the idler pullies as-well if so check to see if back-side of the pullies & belt are worn if so the spacer/washer was not installed properly if at all (bolt & spacer/washer does not come with pulley assy.

Remove the serpentine belt. spin all the pulleys on the system and make sure none are seizing. check for any play in the pulley bearings. if you have a stethescope, with the belt on and the car running, put the probe on all the components and listen for any abnormalities.