Ting / Metallic Sound

[kozakvod]

Thought I'd pose this question to get some feedback.

2013 ISX15 demandated 665000 miles

This past Monday, started it up after overnight in Amarillo. I heard what sounds like a constant ting/metallic noise coming from directly in front of the truck. Quite noticeable. I got it back to Dallas. Started pulling belts to check tension pulley (both of them) and stationary pulley on the AC belt.

1. I pulled the AC belt completely off, started truck, noise still present.
2. I pulled the main belt, started truck, noise gone.

So obviously it's in one of four possible locations. 1. Tension pulley, 2. Fan, 3. Alternator, 4. Water Pump

I oddly enough can't hear (with a scope) any noises that are making that sound. In all honesty I can't get the scope on the fan housing without chopping my hand off so that's a challenge, but with the belt off and manually spinning the fan I don't hear anything. The fan and clutch were replaced 2 years ago. There is no lateral or back and forth movement in the fan, it spins well so I don't think that's it.

I put the scope on the water pump, no odd noise there, sounds smooth and spins freely even with just hand.

Dummy me actually didn't scope the alternator pulley. I did spin it manually and while I didn't hear anything specifically perse' it is quite a heavy spin and doesn't turn as freely as others have said it should? Not sure about that.

I did scope the tension pulley and while I do hear some noise there it doesn't seem like that is issue, even though it could be because even with it off the truck and spinning by hand you can hear the bearings rolling, which is very different from the quiet sound of a new pulley.

So I guess the question is about that alternator. It was 3 years old in Nov 2020. Is there anything I can specifically look at on that thing to help me determine if that's my issue? Any other ideas?

I have decided to replace all tension pullleys and fixed pulley simply because they are original to the truck.

Thanks fellows.