Annoying squeal -not belt related

[tas_nav]

Hey guys I've got an annoying squeal going on. Happens above about 2500rpm only when the throttles pressed down more than about a quarter of the way. It definitely isn't belt related as I have taken the belt off and ran it around the block and the noise remains. It has had no noticeable power loss and I have checked all turbo hoses for splits and re tightened hose clamps. It sounds to be some sort of air or vacuum leak but I have no idea where to start looking!
Has anyone encountered this problem before? Or can point me in the right direction of things to start checking? Any help is appreciated!

Edit: it doesn't matter if it's in or out of gear and its not speed related

 

[bods]

What motor? How many km? I'd assume zd30 going by belt, as they only have the 1. Can you make a backyard stethoscope with a length of garden hose and get someone to keep the revs up while you use the hose to try and pin point where the noise is coming from?

 

[tas_nav]

Yeah zd30. Will try that tomorrow cheers. Was just talking to my old mate google and found that "the tea kettle whistle" is a major sign of a dead head gasket in 6 litres, IM going to assume it's the same with most diesels?

 

[tas_nav]

160000 or so kms

 

[Rumpig]

Crack in the exhaust gas recirculation pipe that runs from the rear of the exhaust manifold around the back of the engine, across to the drivers side. Or exhaust manifold itself.

 

[tas_nav]

Just opened my eyes and noticed a but of soot around the exhaust manifold, the bolts around this soot were very loose, hopefully this fixes it but im assuming the manifold will need to be machined? Is it possible to remove the whole egr pipe and block off both holes?

 

[nuckin futs]

shouldnt need to machine the manifold. just tighten bolts up. if it still leaks just put a new gasket on

 

[Rumpig]

Just opened my eyes and noticed a but of soot around the exhaust manifold, the bolts around this soot were very loose, hopefully this fixes it but im assuming the manifold will need to be machined? Is it possible to remove the whole egr pipe and block off both holes?

Yeah , you can remove the egr pipe and blank it off.

 

[tas_nav]

Problem solved! Not sure of the exact cause, missing a couple of bolts from things and tightened a few up! Thanks everyone for your help, now to tackle the blow-by...