Mack ch613

[Nolan]

Hi everyone, in need for some guidance/ or help.

I have a 2004 Mack ch613 and I am having a squealing noise from the turbo area under the hood, it only does it under a load when it’s hot. It won’t do it cold! It’s been doing it for a couple months now the motor was just rebuilt with new turbo. I replaced the Intercooler and all the intake boots and I have no intake leaks. I’m thinking it’s exhaust but I’m not sure where to start, and help is much appreciated, I also have a video of the sound it makes.

 

thanks

[mrsmackpaul]

You have a air leak between the turbo and the inlet of the motor 

Maybe a split hose at a guess 

And one of those big rubber type of hoses maybe 5 or 6 inches across

 

Paul

[Nolan]

Already replaced the hoses on the inlet side and I’m not loosing boost pressure. Still squeals 

[theakerstwo]

It would help you to find it if you would make you a fitting from PVC pipe and pressure from turbo to the heads with about 25 or more psi.To pressure against the heads you need a pressure gauge and turn the engine slow untill your gauge reaches max pressure> other wise we will be guessing.It could be a crack in the air/air cooler of a gasket leaking on the intake manifold.

[Nolan]

I already did that found nothing and so did 2 Mack dealerships.  Looking to see if anyone has had a common problem or some little trick to solve such a pain of a noise.

[mrsmackpaul]

So you have pressure tested the intake side of things, is this correct ?

And when I say you I mean your actual self not some other mechanic, unless I  see things been done with my own eyes I dont know that they have been done

Apart from your intake side I have no other ideas, at this stage

 

Paul

[Rob]

I'd give a look to see if the exhaust manifold doesn't have a warping issue when hot. Exhaust studs should be replaced and manifold checked for flatness whenever the engine is apart. Seen this problem on many engines over the years myself. 

Wash the engine very clean around the manifold sealing areas and run it hard for a bit ensuring the squeal is prevalent. Allow the engine to cool and then with a very bright flashlight and an inspection mirror, look closely for exhaust "streaking" away from each exhaust port of the manifold. 

[Joey Mack]

Using an inspection mirror or scope... Try to look at the back side of the center exhaust manifold for a crack. I know you said it was re-built. If this truck is an ASET CEGR, then you have a big turbo hanging on by 4 studs. I have found many of these manifolds with cracks. The ASET IEGR can crack too.. Is the air compressor new?  Jojo

[mrsmackpaul]

Would be worth running a straight edge along the heads if the manifold is removed for checking for flatness

On motors with multiple heads like these I always run a straight edge along these mating surfaces to make sure they are lined up, I  have heads that have beem decked on the side that don't even come close to lining up with other heads, not saying it is the problem but only takes a second to check when apart

Paul