Screeching Noise (with video link and audio)

[Delta.Speed]

Hello guys,

As some of you know, I recently finished working on my 2002 LB7.

I've been driving it for the past two days to see how the truck came out, and overall it's running fine but I have a screeching noise coming from the engine when I accelerate and the RPM go above 2,500ish. It only happens when under load though. If I just rev the engine in neutral there's no noise.

Here's the video link on the noise. If anyone has ever heard a noise like that before or has any idea what it could be, I'd appreciate some pointers. Thanks ahead of time.

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[Delta.Speed]

Here's another clip. This time there was no traffic ahead so I was able to stay in it a bit more.

Notice how the screeching comes when accelerating and then goes away for a bit when the trans shifts.

Turbo going bad??

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[2004LB7]

maybe the uppipe gasket. can you see any soot on the exhaust pipes?

 

[Delta.Speed]

maybe the uppipe gasket. can you see any soot on the exhaust pipes?

The gaskets back there are all brand new. I changed them recently as part of the top-end work I was doing.

But now that you mention it, I also have a ticking noise coming from the passenger side that I thought could be I botched the valve adjustment... maybe the ticking is also an exhaust leak.

I personally have never heard an exhaust leak squeal like this though. But I'll take your tip and double-check all my gaskets back there.

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[darkness]

Could be a gasket, could be loose bolts. My truck chirps when my manifold bolts start backing out. The stainless ones are slowly getting replaced as they get loose.

 

[Bdsankey]

I would bet it's a drive pressure leak like stated above. While the gaskets are new, the surfaces aren't always perfect on the manifold/up-pipes/turbo. What I always do is spray my MLS gaskets with copper spray gasket. It seems to have made MAJOR improvements in terms of having leaks. Knock on wood, ever since I started doing that I have not had any exhaust leaks.

 

[Delta.Speed]

Thank you fellas, I appreciate the input. I'm gonna go in and take off all the gaskets and spray them with copper sealant like Brad recommended. I'll come back in and update the thread on the results so it helps out the next guy.

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[Fastshovelhead]

I sometimes will lap or mill the gasket surfaces to make sure the flanges weren't distorted while being manufactured.

 

[Dozerboy]

I sometimes will lap or mill the gasket surfaces to make sure the flanges weren't distorted while being manufactured.

Ya mine where pretty rough and I sanded them down. Everyone seemed to think milling was a little overkill.