2007 Mack AC 350 turbo waste gate

[mimsriggers]

Hi all! I have a 07 mack AC350. I'm getting a terrible screeching sound from somewhere around the turbo. After trying it while sitting I found it started at around 1200 or 1400 rpm. I then watched the waste gate and found that the noise did seem to be affected by the position of the wastegate linkage. I then put a small pry bar between the limit adjust screw or what appears to be such, and the noise disappeared. I'm wondering if 1. that's in fact what these screws are and 2. what it sounds like my problem could be. It seems like I could move the limit screw some and the noise would go away, however if that's the case am I making it so I wont get full boost? Perhaps the waste gate valve is bad? any help would be greatly appreciated. Thanks

[Joey Mack]

the waste gate on that is actually a ring nozzle, and called Variable geometry Turbo. The set screw is factory calibrated. A common air leak occurs right there at the elbow coming off the turbo and the C.A.C. pipe.  

[fjh]

I would check the turbo mounting gasket and all the exhaust gaskets! To find this simply get the sound to happen and run a garden hose over the area the sound will change when you get around the area do this when the engine is in a cooler state not when smoking hot!

my opinion!

[Joey Mack]

Also like fjh is saying, check the intake manifold but not with water.. just visual. I have seen #5+#6 gasket break and sneak out many times..