Exhaust Brake Whistle Noise?

[ykobzar2]

I was going on a 3-hour road trip and noticed a whistling noise starts when the exhaust brake is turned on.

I noticed this noise started happening once temperatures started dropping in Washington state in the last couple of weeks.

I had all of the exhaust gaskets on the manifold replaced about 5,000 miles ago with BD exhaust gaskets.

I have a Steed Speed manifold installed about 30,000 miles ago and a compound turbo setup.

The noise comes on and off.

I noticed that when I accelerate with 20-30lbs of boost, the noise goes away.

However, under normal cruising, the whistle is more common.

This noise is a different whistle than what I had when the exhaust manifold gaskets were leaking.

Previously, it was a loud squeal.

Here, it’s more of a whistle.

Do you have any ideas on what else this can be?

I uploaded a short video of the noise going downhill with the exhaust brake on.

https://youtube.com/shorts/JHz2gFGnO...vEUAQmX5D47oqJ

Additional video of exhaust brake noise: 1st brake application sounded normal, first few seconds of the video. Second brake application you can hear a slight whistle. Third brake application is the full whistle noise which I am referring to in this post.
https://youtube.com/shorts/p941e2m97...1id_8M8HAnwKMv

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[AK Bob]

I listened to the video several times but could only hear a very faint turbo whistle.

Personally I wouldn’t be too concerned.

If it changes the pitch or gets louder, look for any signs of an exhaust leak or soot around exhaust gaskets.

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[Corkey]

Have you looked at the turbo flange gaskets\bolts?

It could have a couple of loose bolts on the turbo.

It looks like you're using the exhaust brake descending, which, if a bolt is loose or leaking by, you could hear a whistling noise.

The leak will allow outside to suck into the leak at the flange.

I might not be able to hear it at all at higher rpm, just from being drowned out by motor noise, etc.

You still make a significant boost, but compounds spool great so that I wouldn't throw out the idea of a boost leak yet.

Have you checked the EBT yet, "Exhaust back pressure tube?"

It's at the front of the engine on the passenger side.

It might be loose at the threads or have a puncture on the hard line.

It's a small 1\4" hard-line, if that.

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[ykobzar2]

Thank you for the suggestions.

I think you are spot on.

i do have a boost leak somewhere in the boost pipe/intercooler.

I am replacing the stock setup with the Bank's intercooler and boost pipes and will be replacing them.

I will double check and make sure the bolts are tight.

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[ykobzar2]

I had a three-hour drive back home today across two mountain passes.

In this video, you can hear the normal exhaust brake sound in the first few seconds of the video.

Exhaust brake is muffled and has a deep rumble.

You can hear the squeal/whistle in the exhaust brake, and in the third and fourth, the squeal/whistle is much more apparent.

https://youtube.com/shorts/p941e2m97...1id_8M8HAnwKMv

A few observations I had.

1. The noise occurs once the exhaust EGTs cool down and remain in low temps, such as when coasting down the hill at around 200-400 degrees.

2. Once you accelerate to “warm up” the exhaust, it goes back to normal until it “cools off” again.

Is there a possibility that the manifold is warped?

This, with cooler temperatures, is compressed and creates a leak.

Does Steed Speed manifold warp that quickly?

My average egt temps are around 600-800, not towing.

The highest I got going up a pass was 1100.

Of course, I’ll go through all the other bolts and clamps to ensure those are tight.

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[Corkey]

On a cold motor, grab a spray bottle and soap.

Coat areas that might be a possibility; as bubbles start to grow and get bigger, you find a leak.

For giggles, have you checked the intake horn for loose bolts?

I have never heard of a steed manifold ever warping.

The heat tolerance can peak up to 2600° on that manifold.

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[AK Bob]

You could also do a smoke test on the exhaust and intake to check for leaks.

AutoLine Pro Automotive Smoke Machine Leak Detector EVAP Vacuum Diagnostic Tester | Shop Series | Assembled in the USA

https://a.co/d/8mVfB9Q

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[ykobzar2]

Thanks @Corkey.

The cold start and soapy water was a great idea and I found the leak.

The cylinder 6 exhaust gasket is leaking.

It started bubbling instantly.

Maybe I bought the wrong exhaust gaskets when I replaced them all?

Maybe go for MLS gaskets?

https://us.bddiesel.com/products/6-7...30073666306112

I'll double-check the torque on the exhaust studs in case they are loose.

I also have a hard time believing the Steed Speed manifold is warped.

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[Corkey]

If I recall correctly, with the VGT manifold, it's a PITA to get back there.

If it's just 6 that's leaking, I think you got the proper gaskets; it's most likely just loose.

I'm glad you found the culprit; hopefully, that's the only leak.

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[myfirstCTD]

Hey if the exhaust gasket doesn't fix your whistle, check the vband clamps on your EGR crossover pipe.

That is where I found my whistle.

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