Strange Noise- cannot figure this out

[71firebird400]

Long time reader, but finally joined the forum out of desperation. My truck has developed a strange noise that only occurs once it’s up to temp and only when I am heavy on the throttle. I have replaced the intercooler boots recently and no change in the noise.

The truck is a 2003 HO, 6-speed, MM3 tuner with a mild tow tune on it. No other modifications.

The noise is not there every time, it tends to come and go. I finally got it on video;

https://youtube.com/shorts/TUIIouFIOzo?si=8Bcu45ngExz4QIhP

 

[Crunch]

My truck has developed a strange noise

I couldn't distinguish the "strange noise" from the other background noise in the video. Any chance you could describe it so it can be better isolated?

 

[71firebird400]

I couldn't distinguish the "strange noise" from the other background noise in the video. Any chance you could describe it so it can be better isolated?

Hi, it starts around the 5 second mark. It's a high-frequency sound....like a high pressure boost leak almost. I am thinking I should check the intake horn and manifold area but I was curious if it's possibly hydroboost related.

 

[Tuesdak]

Check the turbo for signs of rubbing the housing on the compressor side. Check the exhaust manifold for leaks esp #6 pointed to the firewall. Remove engine fan belt and spin each pulley by hand looking for a bad bearing. Esp. the water pump!

When it's making the noise bump the clutch to see if it's slipping or the throwout bearing.

Last idea is what is the HVAC blower motor speed set at? It may have ingested something or have a bearing going out.

 

[Topzide]

That sounds like an exhaust manifold leak. Similar to a reed vibrating in a "kazoo". Which makes sense as the gaskets are made with several layers of stamped steel. I just did my 2014 and found that #6 was the culprit! Mine didn't have that sound on boost but really heard the leak with EB. Feel around a cold manifold for soot build up. Maybe wipe it down the best you can, than after running for a week, check for build up again. Never affected my boost or EB braking, just heard the leaking! Good luck with hunting it down.

 

[71firebird400]

Appreciate all the feedback. Tuesdak and Topzide I went in there and it is obvious my manifold is leaking from cylinder 6. I never thought a manifold leak would make a whistling sound but that certainly looks like the cause of my frustration. I’ll look into what options are out there for replacement manifolds, it sure seems like the two piece units from BD and Diesel Power Source seem to be the way to go. Thanks all!

 

[Topzide]

@71firebird400, Glad we were able to help steer you in the correct direction. I used the Victor Rienz gaskets with new fasteners. You'll have easier time without EGR cooler and other stuff in the way. Might be able to do without the manifold. Gaskets, fasteners and a re-torque might get it done. I keep the engine bay clean to help find just such issues. Started to smell diesel exhaust and started looking, found some soot. Cleaned that up and it reappeared! Then know what I was up against. Mine didn't do the "kazoo".

 

[Tuesdak]

I’ll look into what options are out there for replacement manifolds

Your manifold is likely warped so gaskets are a waste of time on it. I put one of these on my 2003 back in the day as it was leaking on #6 as well.

https://www.genosgarage.com/product/bd-1045987-kit/exhaust-manifolds

I also used a stud kit.

https://www.genosgarage.com/product/studkit8905-a/exhaust-manifolds

 

[bcbender]

My 04 was leaking at both #1 and #6, I took it off and had my local machine shop hit it on the sander to tru it up... was fine after that and not that much $$... I was looking into aftermarket but the OE one served me well for many years.

 

[71firebird400]

BD manifold, gaskets and hardware has been ordered. Should be good to go, thanks again.

 

[Ozymandias]

BD manifold, gaskets and hardware has been ordered. Should be good to go, thanks again.

Oh Mei, I'm to late.
I had one of these and it leaked at the connection of the two halves.
Amazon and BD played the we deny warranty game with me.
In the end I bought a new OEM from Genos and it serves me well - and doesn't leak.
Don't do studs, the bolts work excellent.

 

[BigPapa]

I had an ATS on my 12-valve that never gave me a problem. We’ve had to use Exhaust Sealer on a few Cummins exhaust manifold joints.