egsol631

i just replaced a radiator and both drive belts to the motor the serpentine belt and the ac pump belt 2 seperate belts ,

i had replaced these items because the idler pully had gotten loose let the serpentine belt loose and the radiator exploded , i found the nut and washer for the idler pully on the ground looked in good condition still so i took off both old belts put new ones on and tightened up the idler pully now when i started up the car the pully is getting loose again !!!! i can see that the nut holding the idler pully is turnin loose wtf !!!!!! i had it on tight and now what im stuck.... please help assap

mech361

The pulley shaft fits in a slot on the bracket, and has to be turned the correct way or it will come loose. If it's in the slot correctly it won't turn.