This started happening a few days ago. Its loud enough where I can hear it over the engine running sitting in the truck with my windows down and hood closed. It only does it when the engine is running and does not appear to change with RPM. I double checked the TB and it is fine. I havent changed anything in 2 weeks and then this starts one day...

http://www.youtube.com/watch?v=SPUZ5Osyawg

Any suggestions?

 

at first just by reading the title i was going to say thats what the blower does...
but reading the thread and watching the vid... sounds like a vaccum leak or somethin, def not supposed to be there. Is your truck a SD tune?

 

Yep, 2bar SD.

I couldnt see anything wrong when I put the scanner on it (hptuners), and there is no change in drive-ability.

I thought vacuum leak too, but from where....

 

There are a few threads of a problem like this that turned out to be a vacuum leak. As i recall it was an easy fix.
If I run across something I'll post up.

 

carb cleaner is your friend when looking for vacuum leaks

 

care to elaborate?

 

im not completly sure if it works on newer LS engines but i dont see why it wouldnt.

spray carb cleaner around any vacuum hose, or anywhere vacuum could leak, if/when you hear the engine increase in RPMs, you found it. works wonders when i was chasing a vacuum leak a few years ago

 

Man thats loud. I would think vacuum leak, what do your trims look like? What about the boost a pump? I heard they sound like a jet.

 

i have an in-tank walbro 255

the leak is very loud, loud enough to hear over the truck sitting at a stop sign with the hood closed and windows down.

trims are within 3% at idle

turning on the AC doesnt change anything for what its worth

 

Alternator... Hell I don't know, sounds electrical.