I may have determined what the noise is...it is an affliction known to the 2nd gens.

I took a drive in my fathers 99 CTD, and it has a very similar noise...a noise that even has a TSB. His has had the coolant whistle since day one...it has something to do with a nipple on the cooling system. It is almost exactly like my noise, same warbling squalling noise...

So I'm going to concentrate on this a little more, but I'm going to say its most likely a found deal.

 

Not sure wat gen a 98 24v is, but one of my friends replaced his today because it was cracked. Also would it being cracked right by the turbo cause loss of power? Sorry didn't mean to steal your thred.

 

A 98 is a 2nd gen...and they are known to crack manifolds...and a loss of boost would cause a loss in power, and the crack doesn't have to be big.

 

Well, a little more digging...

I've determined its something controlling the turbo that is causing my wavering whistle or warble. Its not a leak, its something causing the boost to lightly fluctuate...but not something I'm seeing on my Outlook. Recently the Outlook has started doing weird things, so I decided to pull it offline. The reason I think its something controlling the turbo is that it comes and goes, typically "resets" once the truck is restarted.

Upon removing the wiring, I noted two OLD nicks in the Outlook wiring at one of the connectors...neither seemed through, but I'm wondering if it shorted the Outlook out when it was damaged? It was in the wiring between the outlook and the main wiring harness of the truck (not the wiring between the MAP sensor and truck wiring).

I'm not sure if this was the cause, I haven't driven it since. If this doesn't fix it, I'm going to replace that solenoid on the turbo as my next move.