It's not a belt

[Shakeymike359]

2009 Pete 388
ISX 79329607 (esn)
I'll keep it as short as possible. I started working here April 3. Fired her up while I put my things in the truck and right away a loud screeching sound I took for a belt. I'll deal with that later I told myself, it was now the 5th and a load of 9 cars was waiting. The noise faded upon warming up and for the first few weeks was barely noticeable.
Then came the "nosedives". A pair of back to back episodes where upon my getting into the throttle, all manifold pressure dropped with what could be felt in the seat going from a slightly positive g force during acceleration to instantly a negative g force (throwing you forward against the windshield if exaggerated) combined with the empty, throaty sound like an engine just puked. It may seem silly but I can't describe it any other way, but all this I felt under my right foot.
Weeks go by and the screeching slowly becomes louder. Week #5 and I get the first​ call for a Regen. I park and hit the switch while I air up a tire. Son, you talk about loud. Screeching was louder than it ever been and the engine revving up, down, up, down. 30 minutes she was done and it took a lot of the screech out for the next week. Back to hardly noticeable. But shes back to loud as ever and I tell the owner since I'm heading back towards the shop in Florida he should take a look at the turbo. I'm concerned the bearing is fixing to lock up and I'm hearing metal on metal screeching. I'm trying to avoid a several thousand dollar increase in cost to repair out on the road over what could be repaired in house.
3 days after I get in I'm back to a truck left untouched. Oh that's nothing major maybe a belt is what Mr "been in the truckin' binness 30 years" expert assures me.
I'm no expert. But I'm pretty damn good with a wrench in my hands going back 25 years to a teenager swapping out engines and tranny's laying on my back in gravel. I have a vast knowledge of all things mechanical in particular the workings of the internal combustion engine, 4 stroke, whether it's spark or pressure the source of ignition.
I've done some research lately online with much of it coming from this guy named Rawze.
Sidetrack- its a rare delight to watch video and read information from someone that all the while allows me to keep up by explaining what he's doing, how he's going to do it, and why hes doing it. From video#1 on EGR tune up where he says he's never done a video before I must say a better job couldn't be done by anyone. Thank you sir.
I'm leaning towards VG actuator or related. The thing is nosediving everytime I downshift. Big truck behind me pulling a hill beware. That car hauler in front of you is gonna drop 15 real quick and you oughtta left lane it even quicker. I'm letting her do her thing and just keeping pedal down until she coughs her way out of it. 4-5 seconds and by that time R's are lost and another gear needs to be found.
Hey, if it comes to a meltdown of all 6 pistons it'll be on Mr Truckin' biness.
I have video of a gear drop episode[/size]