my friend has a jeep grand cheorkee, dunno wut year exactly, but it was squealing pretty bad, it has a manual tensioner so i tighened it and the squeal went away, just wondering is there any official spec on tighten it or is just a tighen it till its not noisy deal?

well what year and what moter does it have

its a straight 6, dunno the year or displacement

most likely the 4.0

i don't know about the adjustable tensioner though