C15 twin turbo squeaking noise on 2005 Pete 379

Does it get louder as you the boost/rpms go up? Could be a small air leak, check to make sure the exhaust is all tight.

 

Check the bellows pipes and all the boost boots. If those all check out, look at the CAC.

 

How many miles on motor? Have your turbos been replaced?

 

first check the CAC for any leaks.i had the same issue on Detroit. it turned out to be blown gasket at one of the exhaust manifolds.check the for leaks on the exhaust manifold as well(LOOK FOR BLACK SOOT)

 

I’m having a similar issue with my CAT. Did this end up fixing it?

 

The squeaking is probably the gasket between the inner turbo and manifold. Probably a broken stud, or at least a nut or two backed off. Don't wait too long to fix it. It will be completely blown out in a few more days. Tightening it won't help, it's already cracked or a piece blown out if you're hearing it.

That engine (guessing MXS) will also tend to blow out the exhaust gasket on cyl #6 every now and then, that's usually a broken stud. Obviously check them all and replace any that are broken or sketchy looking. Since you already found the exhaust leak on the manifold to head surface, the turbos have to come off anyway to get at it. So the first problem I noted should get fixed as part of the job. Check/replace those studs as needed.

While you're in there, look around to see if that hot exhaust leak melted anything near it. Wiring conduit, evaporator drain, hoses, etc.

When you get it all back together, you'll have to go over those flange nuts and flex coupler clamps about a half a dozen times before they stay tight. Plan an extra 5 minutes in your pre-trip and do it while the engine is cold. Obviously don't over tighten, but you'll notice about the 3rd or 4th time you do it they are more tight than the first time. The flange nuts are a booger to get at with tools, so a cold engine is your friend for those.