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Mack mp8 squeaky noise from engine


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Have a noise coming from the engine can not really hear where it’s coming from . Seems like a belt squeak or something like that but only does it in higher gears and while in gear does not do nothing on idle . Also have to be on the pedal halfway or all the way down kind of noticed when boost goes over 20psi. I’m thinking it might be something turbo related have noticed my boost did not go past 30psi when I noticed this issue . It used to easily go 34 paso to 36 while loaded . Just trying too see if anybody has encountered something similar.

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Ok yes I gave it a look today dint see anything found one small leak but dint fix the problem . I still don’t get past 30 psi and have that squeaky whining noise while in high gears and over 20 psi . I’m a keep on checking just ordered a turbo boost leak tester . 

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'F' is onto something!!  the orings at the tube he is talking about are a pain in the a$$..  all it takes is for the oring to split, and the leak starts.. iit is a squealing sound under a load.  you wont see it til you take it apart..  jojo

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1 hour ago, Rsc1717 said:

Ok found the issue cracked intake manifold . How should I go about removing it dint want to break any bolts . 

if you found a cracked intake you likly already have a broken bolt! is the crack at the front just below were the egr tube enters ? if so look for a missing bolt at the bottom

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32 minutes ago, fjh said:

if you found a cracked intake you likly already have a broken bolt! is the crack at the front just below were the egr tube enters ? if so look for a missing bolt at the bottom

It’s on the driver side of motor intake manifold don’t know if theirs a egr tube by their . And yes crack is like 5 inches from beginning of intake started at the bottom and worked it’s way up pretty long crack . Trying to find the torque specs for intake manifold. 

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There is a service bulletin on the intake manifold bolts . They came out with some new longer bolts with spacers on the ends . The broken bolts and intake manifolds we’re common more on the MP7 than the MP8. But seen plenty of both . The broken bolts usually come out easily sometimes with just using a pick to spin them out. If you do have to drill them they are very soft and drill easy. 

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Mack service bulletin SB214061 shows the new design intake manifold for MP8 and MP7’s that use the longer bolts but no spacer. If your intake manifold is not broken and your just replacing the broken bolts the service bulletin SB214057 shows using the longer bolts with a spacer , I will try to attach links to the bulletins 

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4 minutes ago, Mackpro said:

Good reminder FJH, ask for new bolts because with the new thicker manifold the old bolts will be to short, 

A good parts guy would know to offer the bolts However ......................!

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