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So a couple of weeks ago, my truck started making this short "pew" noise directly after it starts when the engine is cold. Only last like a second and it happens just as soon as I release the key from starting. Seems to be worse if its colder outside but will even do it when its above 60F. Once the truck has been driven and reached operating temp, it will not make the noise when you start it again. the truck pretty much needs to sit for a day and completely cool to make the noise. The truck starts just fine, runs and idles just fine. I have an Insight CTS and all temps and pressures are the same as they always have been. The truck is up to date with all maintenance. I have realized though that the noise started directly after an oil change! I changed my oil on the 5th and I first heard the noise on the 9th and its very possible that I didn't drive any between those days. Changed oil with 10qts of Rotella 5w40 and a Mobil 1 filter, same as always. The only thing I did different was I changed out my factory oil drain plug with a PPE magnetic plug. Feel like this shouldn't be related but its the only thing "different" I did during the oil change. I assumed the noise was belt chirp so I installed a new belt, both idlers, and tensioner prior to this post. Please see link for video of noise.

 

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Discussion Starter #2
Anyone?
 

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Diesel Technician, Formerly Mwy123
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It sounds like pressurized air coming through a small opening. If you think its belt related, drop the belt and start it up. If you are still getting the noise, could be the turbo barking. Completely wild guesses. Keep driving.
 

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Discussion Starter #4
It sounds like pressurized air coming through a small opening. If you think its belt related, drop the belt and start it up. If you are still getting the noise, could be the turbo barking. Completely wild guesses. Keep driving.
In person, it doesn't sound quite as much like air as it does in the video. To me, it kinda sounds like the starter spinning. But I would think if I was having starter problems, it would do it all the time, not just cold. I wouldn't think turbo because it acts just fine driving. Veins cycle just fine and boost pressure is the same. I plan to just keep using it and if something is breaking, it will tell on itself eventually.

Next time I start it cold, I may get my wife to start it and I can listen, mayne I can pin point the location better.
 

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Welcome to DieselPlace

I would guess up pipe connection or gasket, by the sound of the noise on the video
 

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Discussion Starter #6
I would guess up pipe connection or gasket, by the sound of the noise on the video
Never thought about that. Wouldn't a leak from the up pipe just get louder with exhaust pressure? No noise at all other than just a second right after it starts. No drop in boost either.
 

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Never thought about that. Wouldn't a leak from the up pipe just get louder with exhaust pressure? No noise at all other than just a second right after it starts. No drop in boost either.
It could be that the initial startup is just enough pressure to push through to make the noise, then stop.
 

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That video sounds really similar to this up pipe noise
 

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Discussion Starter #9
That video sounds really similar to this up pipe noise
2015 lml durmax 6.6 up pipe leak - YouTube
I guess because I am use to hearing it in person it doesn't sound as similar to me. However, I am up for checking into anything. Im thinking next time I start it cold, I'll have my wife do it and I can be under the hood to see if I can better pin point its location.
 
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