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loud chirp/whistle MP7

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Intermitant LOUD whistle under heavy acceleration. Starts as chirp and then loud whistle. Checked turbo boots and exhaust clamps and all tight. Any ideas? 2009 MP7

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Has any work been done recently? Could be a leak at the egr hot pipe, exhaust manifold, turbo, intake manifold, and charge air cooler. Seen them all but need to know if anything was done to the truck recently.

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The outlet hose clamps off egr cooler , cracked intake manifold.

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New flex pipe was installed under cab and all clamps were replaced from turbo back to burner box...have rechecked all of the clamps and are tight and no exhaust leak trails seen...wondering if possible carbon build up in EGR may cause it

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Check all of the above that was mentioned. Also check the back side of the flex pipe that was changed.

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could be belts,my RD was doing the same thing

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The EGR valve is not cleanable and will need to be replaced. Be careful as the bolts mounting it like to break off. I have a trick that works most times. I use a crack torch and heat the manifold where the bolts go in and work the bolts back and forth while spraying with penetrant and re-heating the area while working the bolts. If one breaks off the manifold will need to be removed. I have saved a lot of manifolds by extracting or using a carbide bit to remove the broken bolt and installing heli-coils. If they come out make sure you run a tap through the threads and use plenty of nickel anti seize on the new bolts.

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Most of the time I hear this its usually a blown exh. manifold gasket. Usual suspect is #1 port. You can see the soot trail at the rear side of the port. Most manifold slip joints leak as well, you could try to replace the seals but most slip joints are blown out or have excessive etching. There is a new updated manifold that has bellows between the sections, has thicker flanges. Its not too expensive either, most certainly cheaper to replace than to try and drill and helicoil, never liked doing that to manifolds anyway. Not knocking it, just not my cup of tea.

If this is the case and you want to repair yourself, know the correct torque procedures and NEVER reuse exhaust fasteners. Use never-seize on all threads.

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I just got finished chasing this same problem. I first thought that it was a tensioner, because at idle, the squeal was small and got louder as RPM got higher. Changed both and only one was close to bad... yeah, it had a little wear but I put the old one in my parts box for road calls (just to get a truck back to the shop and save a tow). Anyway, like trukster said, after a good bit of close listening and pinpointing I found soot under the #1 exhaust port. The bottom of the gasket had blown out. Time to pull the turbo off and install new manifold gaskets. You will also need to put a new trubo gasket on when you reinstall it, DON'T try to re-use ANY gaskets. The torque for the NEW manifold bolts is done in a specific sequence, and done in two steps. If you need the specs, I will post them here tomorrow.

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Was there any power loss from the exhaust leak? I'm having same sound but losing power and boost when I hit any kind of hill that requires mashing the pedal.

 

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