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  #1  
Old 11-18-2019, 10:31 AM
11Sterling 11Sterling is offline
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Default Whatís the squeal and screech?

Okay 2011 6.7 with 161K on it, bone stock. Last Thursday, I notice a slight and very faint whine almost like an A/C issue. Same thing Friday. Saturday, took the truck out to the desert to scout for sheep and all good. Sunday, out to the desert to scout again, all good. Then the afternoon to run around town with my wife and then the squeal started. Low rpms rolling through parking lots in 1st and 2nd, the truck has an almost metal on metal screech that is way louder than anything Iíve ever heard with the windows up. I remote start it this morning while walking out of the house and the squeal goes on for about 30 seconds. Very loud at first and then dies off to a very low squeal. The whole way to work each time I press the throttle or get it on it to pass it comes on again. No CEL or warnings. Anyone have the solution on this one? Iíve read all over and it seems that no one has an exact answer. I need to have the truck 100% by Friday night and I canít afford to have it down for more than an afternoon right now. Any help is appreciated! Going to wash the dust off after work today and start looking at it tonight. Itís also worth mentioning that itís always had a slight squeak on shut down from a belt, but itís become more intermittent the last few weeks. Iíve owned the truck for a year as of yesterday. Thanks!
  #2  
Old 11-18-2019, 11:12 AM
Zeb Zeb is offline
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Sounds like an exhaust leak, pre turbo. Vane position differences dictates the varying level of exhaust back pressure and thus the changing noise level.
  #3  
Old 11-18-2019, 12:35 PM
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6.0 Tech 6.0 Tech is offline
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What zeb said. Sounds like a broken exhaust manifold stud. The gasket acts like a reed and makes a god awful squeal depending on back pressure. Roll under yhe truck with a flashlight, usually its the rear most studs that break. There is updated stuff to replace it. Basically goes to 15+ hardware.

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04 cclb IDP and TSD tunes, KC Stage 2 hi pressure, S476 atmosphere, Odawg Stage 2 ported intake, RCD Stage 1 cam, RCD lifters and pushrods, RCD 120# valve springs, ARP 625s, o ringed heads, Warren 7mm 250/100 hybrids, Strictly bowl dereete regulated return, Air Dog 2 4g, Snow stage 2 water/meth
  #4  
Old 11-18-2019, 02:33 PM
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sootie sootie is offline
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either that or the compressor wheel is contacting the housing in the turbo.
  #5  
Old 11-18-2019, 02:44 PM
11Sterling 11Sterling is offline
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Right on, thank you guys. I’ll crawl under the truck tonight and check the studs at the manifold.
  #6  
Old 11-18-2019, 04:16 PM
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jbolen323 jbolen323 is offline
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Quote:
Originally Posted by 6.0 Tech View Post
What zeb said. Sounds like a broken exhaust manifold stud. The gasket acts like a reed and makes a god awful squeal depending on back pressure. Roll under yhe truck with a flashlight, usually its the rear most studs that break. There is updated stuff to replace it. Basically goes to 15+ hardware.

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I can upload of what mine sounds like if youd like a comparison.... Maybe we can do a DIY / Video Tutorial about this issue.
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  #7  
Old 11-18-2019, 07:57 PM
11Sterling 11Sterling is offline
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Finally got home. Someone give me some bearings on where to look at exactly?
  #8  
Old 11-18-2019, 07:59 PM
11Sterling 11Sterling is offline
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Quote:
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Finally got home. Someone give me some bearings on where to look at exactly?
PM me your number and Iíll send you the video I took when I fired the truck up after work today!

Iíll figure out how to upload off of my phone at some point.
  #9  
Old 11-18-2019, 08:39 PM
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Quote:
Originally Posted by 11Sterling View Post
Finally got home. Someone give me some bearings on where to look at exactly?
Underneath, look up at the motor, right basically at the top of the bell housing. You'll see where the up pipes come off the manifolds, there are heat shields up above the manifolds as well. They'll probably have a bunch of black on them. You should also be able to see the nuts on the studs that hold the manifold to the head, if theyre broken. You wont be able to see the nuts, and the spacer may be gone too.

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  #10  
Old 12-07-2019, 10:39 AM
11Sterling 11Sterling is offline
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To update everyone on this - I had the truck taken in 2 weeks ago and looked over by a mechanic I’d had referred to me. He inspected everything he could without having to tear into the truck and start spending money. The only item he could find suit on was the pressure tube that comes off the turbo up-pipes referenced in TSB 11-6-22. He felt confident the issue was somewhere close and not manifolds/studs. I took the truck back in this week and sure enough he was right. $364 later, in lieu of $3K to replace the manifolds, the squeal is gone. He does need to go back in an re-tighten the fittings a little bit, or I do because there is a very faint sound at times when I get on it hard at 1150 rpm. The truck was wayyyy worse than that prior to replacement and would squeal essentially all the way to 1500 rpm and 1900 in higher gears. Either way, hopefully this is helpful. I fully expected to be replacing manifolds and it was not the case. Just one of those things to double check. Thanks everyone!
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