help my truck is making this noise and I don’t know why! I have a 2005 Dodge Ram 1500 with a 5.7L hemi engine. Just recently in idle it makes this noice/rattling sound and I don’t know what it possibly could be. I just replaced the belt tensioner and nothing worked. Please if anyone has any idea I would greatly appreciate it! Thank you!

 

It sounds like it could be an exhaust leak/broken header bolt. One check for exhaust leak is taping a strip of toilet paper over the area where the headers and exhaust manifold meet. Start the engine and see if air blows by the toilet paper. There are some other checks you can find in a search.
You could try moving the headers to see if they are loose.
If not exhaust leak, consider getting an auto stethoscope.

 

Can you see any blue spark when looking at the plug wires?

 

Maybe cut down the possibilities. Take the belt off and start it for just a few seconds.

 

There is an idler pulley towards the middle of the engine, see if that one is no good.

 

thank you very much for the advice it turned out to be one of the idler pulleys

 

it turns out it was the idler pulley! It was shot and couldve broke at any moment so thank you very much!

 

Excellent ! Cheap fix too, put your old tensioner in the good used parts box
.