I drive a 1996 Dodge Ram1500 with a 318, it's my first Dodge and other then a major sludge issue(3 leters of dextron/mercon, a high volume oil pump, 3 plugged solid pickup screens and some time solved that issue) it has been a very good truck to me. Last week I was sitting at a light on my way home and other then the nice sound of the twin flowmasters, I heard a chirping. When I gave it gas it went away, and back again at the next light. When I arrived home I pulled it into the garage so see if I could figure out what it was, I couldn't find anything loose and the sqeeking noise was still there while at an idle. I had thought maybe one of my rockers wasn't getting enough oil at an idle, that wasn't the issue after pulling the valve covers and watching the oil flow all over the rockers, both sides, then I started to look a little more twords the serpintine belt, but the sound really didn't sound like it was coming from there so I didn't bother to much with the belt drive area. Long story short I had a mechanic friend look at it and he told me the Belt Tensioner wasn't springing back as well as it should and there was a little slop in the belt, So I changed the Tensioner and the Belt.
Tensioner $59.99 and GatorBack belt $27.99. "YES problem solved I said"..... I gave it a little gas and when it went back to an idle the same noise came right back. Now im scratching my head, all the pulleys have greese and oil, There not making any noise that I can hear, the noise is coming from the back of the motor or somewhere and it really is annoying, I can hear it in the cab and anyone can hear it if they pull up next to me with the windows up. I'm still gonna do a little more poking around this weekend but I really don't know what else to look for not very firmiliar with a Dodge (Previous Ford truck owner). Anyones advice I am more then happy to hear, feel free im all ears [sm=helpout.gif]

 

squeak from the engine could be any of these. you can prove it by temporarily removing the belt and letting the engine run for a little while. (just watch temp and don't overheat, since the water pump won't be turning)
1. tensioner pulley/spring.
2. idler pullery.
3. alternator.
4. power steering.
5. AC
6. water pump
7. clutch fan.

these can be a little hard to track down. what i do is use about a 3' length of pipe, pvc or conduit, it doesn't matter, and place one end against the truck part and the other end at my ear, and it acts like a stethoscope. good for pinning down noise. you can move all over the engine and hear valves, pistons, bearings, etc. BE VERY CAREFUL - DON'T STICK THE PIPE INTO A MOVING PART.

here's a non-engine squeak that drove me crazy. it would do it while it as sitting in the truck while stopped or going slow. when i'd get out at a stop, it would quit.
https://dodgeforum.com/m_657737/tm.htm

 

i had the same problem with my car ... but i think this is the nature of diesel engines once they get old they seem to make strange noises ..!!!

 

idler pully.. they are common for this... replace idler pully

 

how many miles on engine? it could be the distributor bushins going bad any change in performance. but i would have to agree remove belt to narrow issue down does it have a fan and a fan clutch fan clutch could be making noise