I have a 2013 Dodge Ram 1500 Hemi 5.7 144k miles, strange squeak sound coming from engine at idle or lower RPM. I changed the belt, belt tensioner and Idle Pulley, to no avail. Next option is to change the Alternator but I'm not showing and real signs the Alternator is bad. Water pump shows no leaks and it's not a constant squeak. You can hear it every 3 to 5 seconds or so. Looking for any other possibilities.Started about two months ago and is very annoying.

 

Remove the belt and start the engine. If the sound disappears you know it is a component that is operated by the belt. You've already replaced the idler and tensioner. Next likely culprit is the alternator. I am changing mine this week.

 

Thanks for the quick reply. I just ordered an new alternator and will replace tonight. Will do as you suggest first however.