Turbo Noise?

[Bs702]

I just got my truck back together after putting a set of used BD compounds on, I went to take the car for a drive and heard a screeching sound like the compressor wheel is hitting the housing, but everything sounds satisfactory at idle.

I pulled the piping off and looked at the compressor wheels from the front; they do not appear to be contacting anything.

I should also add I had the head off for a broken manifold bolt before putting the turbos on.

New head gasket, assembled and set valve lash. Any ideas? I would post a video, but the site will not let me.

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[Corkey]

It could be a crack in the exhaust manifold that is screeching.

Does it do it when the motor is cold?

Generally speaking, when the manifold is cool, you have less chance of seeing or hearing it.

As the steel heats up, the crack starts to show itself and screech louder hot than cold.

Try spraying soapy water on the manifold. Bubbles will develop, and that will be the culprit.

As you stated, at idle, it's OK. While under a load, you start to hear it.

As heat develops "under load" at the manifold, the crack grows as well as the screeching.

Thats where I would start

Edit:

Another thing could be that one of the ears on the gaskets might not have been sucked down tight enough

Or the turbo flange might be bypassing exhaust

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[Bs702]

I let the truck idle in the driveway for a while before driving.

Still, I will check tomorrow to see if it will do it right after start-up, I read other people having issues with screech noise being the manifold gaskets, so I re-used my old ones as they looked okay but thinking it probably wasn't a wise idea now.

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[Corkey]

I bought the ARP exhaust studs just for helping to align up the gaskets.

They make it much nicer than the stock bolts and holding the manifold.

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[Bs702]

I bought the ARP exhaust studs just for helping to align up the gaskets.

They make it much nicer than the stock bolts and holding the manifold.

When I put it back on, I went with factory replacement bolts for the manifold.

The old gaskets came off the factory manifold so maybe they aren't sealing well to the 3 piece that came with the turbos.

I picked up a set of Mahle replacement gaskets tonight; I will swap them out tomorrow and see what happens.

Hoping that is all it is!

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[Bs702]

I pulled my bottom turbo off to make more room for manifold access, backed bolts off, and replaced the gaskets one by one; the Mahle multi-layer gaskets looked a lot better; I cranked all the bolts back down on the manifold, but the rest of everything back together and took the truck for a short ride and the noise appears to be gone, didn't get too crazy as my downpipe isn't on at the moment.

Still, I'll take it for a longer ride later this evening with the truck at operating temp for a while and see if the noise returns.

I'm not much a fan of the three-piece manifold as a couple of the bottom bolts are right up against the manifold and leave no room for a socket, so you're only able to get small turns on them with a wrench.

It would be a better design if there were recesses for the bolts.

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