I have this 2004 Dodge Neon 2.0. the PS/AC Belt was gone. so i went to get a new belt today. I went online & found out how to route the belt. so i put it on CORRECTLY & the belt pops right back off when cracked in idol. i KNOW i have it on correctly. so in your past experiences with this type of thing what could be causing the belt to come back off after putting it on right. I was thinking the Tensioner Pulley might be wore out. seems to me the tensioner pulley should have a lips on it to keep it from allowing the belt to slip off. but then again the PS & AC Pullys have lips on them & their in a rut so it should keep the belt from coming off. Can you help me please.

 

Bent or worn pulley could do it. Is it making any noise, or just popping off?