Originally Posted by camodown
Could be something like an idler pulley going out. Start your truck up and pop the hood to find where it is coming from. You can use a long screw driver and place it on stuff and put the handle next to your ear to amplify the sound.
Great idea. I'll try that when there's daylight.
Originally Posted by Nevermore
How cold is it where you live? It could just be normal truck warm up noise if it's cold.
It's cold every so often here in N Texas, but it doesn't always happen when it's cold.