Questions about Cummins ISX

[TractorHauler]

I've got a 2005 Volvo with an ISX Cummins with around 680,000 miles on it. It seems to have a squeek or chirping noise which sounds like it is coming from under the valve cover. I checked the belts first to make sure it wasn't in that area and it is definitely not them. It goes away once the motor warms up. What would be the cause of this? Thanks for any help!

[COLT]

Maybe an exhaust leak

[bob h]

I've got a 2005 Volvo with an ISX Cummins with around 680,000 miles on it. It seems to have a squeek or chirping noise which sounds like it is coming from under the valve cover. I checked the belts first to make sure it wasn't in that area and it is definitely not them. It goes away once the motor warms up. What would be the cause of this? Thanks for any help!

Sounds like a compression leak. If so, it should get worse. Engine light on?

[TractorHauler]

The truck does not have any check engine lights on and it runs very well. I wanted to also add that it only does it when the oudside air is 25 or below. Could it possibly be needing an overhead run? Also, what makes these ISX Cummins motors hunt every once in a while at idle. It doesn't do it that often, just something i noticed. I am used to by Cat motors which idle very smooth.