Help with Noise at Idle

[Jake707]

Wasn’t sure if this was the right place or not so feel free to move Admin if not.

Here’s a video I took from the passenger side wheel well. This higher pitch sound is driving me nuts. I have no idea what or where it is coming from. It’s only at idle and you can here it go away with throttle. It sounds to me like it’s coming from the back part of the engine. It’s def on the passenger side vs the drivers side and you can’t really hear it from up top. I think it’s coming from the filter assembly area but that doesn’t mean it’s true. These sounds can travel for sure. Any suggestions would be greatly appreciated. I’d like to put the wheel well back on but this sound is loud and annoying.


https://youtu.be/H2aPx--2ecA

 

[gmac32]

It is something vibrating. Just start grabbing thins with your hands while it idling and see if it goes away. Maybe you are starting to get an exhaust leak

 

[Jake707]

Haha. I’ve tried grabbing everything I could think of in that area thinking the same thing couldn’t find anyway to alter the sound.
Exhaust leak huh. Would that only be at idle and not under pressure down the road.

 

[gmac32]

Depends. At idle yes if the vanes on the turbo are closed creating acupressure. I would think you be able to hear it going down the road.

 

[gmac32]

Just listened to video again. Check your heater hoses. I don't think it is exhaust. It is harmonics

 

[KyleC4]

Try checking that bracket on the passenger side up pipe that your down pipe support bolt goes through. Sometimes a small crack forms and then the metal vibrates against itself.

 

[Chevy1925]

Try checking that bracket on the passenger side up pipe that your down pipe support bolt goes through. Sometimes a small crack forms and then the metal vibrates against itself.

^^ i was going to suggest the same

 

[cdbright]

FYI i chased the heat shield rattle on the down pipe noise for about a year. It was my old LMM , but it almost impossible to track it down, ended up finding it by prying on the shield for a guess and it went away.

 

[Jake707]

It has a MBRP down pipe so no heat shield but the support bracket to the up pipe is a possibility. Now gotta figure out how to test they.

Heater hose I don’t know where that would be either but I thought those were rubber?

 

[rmallen30]

Is the trans dip stick tube or the brace for it hitting the downpipe or the 2 bolts for the brace loose

 

[Jake707]

Ok went out on lunch and was grabbing and prying all around. Finally was able to affect the sound by prying between the down and up pipes. So I focused on that bracket connecting the two. Everything looked solid, nothing touching and was tight. So I said F it and shot a little wd-40 on the bolt head and it all went away. Wiped it off and took it for a little drove and still nothing. So I soaked the shit out of it haha. Not sure what the issue is but for no it’s quite. Will see how long it lasts. But at least I know the area now.

 

[Chevy1925]

that tab isnt being held down well enough. the end of it is most likely vibrating.

id also verify the hose clamp for the heat wrap is tight and the v-band for the down pipe is tight.

 

[Jake707]

Just to clarify this is where I originally put a tiny bit of wd-40 and it went away. I also adjusted the hose clamp just to ensure it was not touching the up pipe so there’s plenty of clearance there and the v band I double checked it was tight as well. To the point I thought it was going to break if I turned it.

 

[Chevy1925]

unless the bolt is loose or you have an exhaust leak, thats not going to be it. much more likely the WD got down under that black tab and stopped the slight harmonics its creating at idle. there is hardly anything holding it down so its going to be moving/vibrating.

 

[Jake707]

Ok. Maybe I’ll go in there, remove the bolt and put a small washer between the down pipe tab and the up pipe bracket. This would space them out enough and create a solid contact right.

 

[KyleC4]

unless the bolt is loose or you have an exhaust leak, thats not going to be it. much more likely the WD got down under that black tab and stopped the slight harmonics its creating at idle. there is hardly anything holding it down so its going to be moving/vibrating.

^exactly. Look more into this for that rattle. The crack can be really small and it usually happens along the weld on that bracket. So like James said the WD40 probably filled the void and created a buffer.

 

[Chevy1925]

Ok. Maybe I’ll go in there, remove the bolt and put a small washer between the down pipe tab and the up pipe bracket. This would space them out enough and create a solid contact right.

Realistically you need a thick/wide washer under the bolt that fits tight to the bolt, then cinch it down. Putting the washer under there doesn’t fix the two issues you have (noise and lack of contact bolt to tab)

 

[Bdsankey]

^exactly. Look more into this for that rattle. The crack can be really small and it usually happens along the weld on that bracket. So like James said the WD40 probably filled the void and created a buffer.

Realistically you need a thick/wide washer under the bolt that fits tight to the bolt, then cinch it down. Putting the washer under there doesn’t fix the two issues you have (noise and lack of contact bolt to tab)

X3, the tab needs to sit on the washer(s) before you tighten the bolt or else you're fighting the clamp on the charger and won't ever get it to be quiet.

 

[JoshH]

I would just remove the bolt and throw it away. If you look at the factory bracket, the strap wraps completely around the down pipe and is welded to the pipe on the back side of the opposite side of the tab. Having it built like that creates a point where the tab is flexed back and forth and ends up breaking the tab of the pipe over time similar to how you can break a solid wire by bending it back and forth a few times. I've had to fix more than a few of those that had gaping holes in them.

 

[Jake707]

I took the bolt out and there is no space to put a washer between the two the were sandwiched together pretty good. I ran it for a min or so with no bolt to see if anything would want to settle and not bind up. Looked the same so I put a washer on the bolt and ran it back in and made sure it was tight. We will see if the noise comes back. I hope not. If it does then there’s more than likely a break like mentioned. That would mean down pipe comes off, then the up pipe, then since the up pipe is off might as well replace it with a LB7 style or cut and weld it, then might as well delete the egr fully, then I would need to tune out that system so EFI live. Haha. As you can see things tend to escalate quickly at my house. It’s either a $.10 washer fixed it or $1,000 will haha