Hello,

I have a 2008 G37S coupe with a manual transmission. I have noticed a rattling noise when I accelerate since I bought the car 1.5 years ago. It sounds like the sound is coming from underneath the vehicle and not the engine bay, but I can't be sure. The sound seems to come and go.

Take a look at the youtube link and let me know if you know what it might be. The Infiniti dealer couldn't diagnose it as they were unable to reproduce the sound.

https://www.youtube.com/watch?v=i_QQ...ature=youtu.be

 

I am not a mechanic and definitely not an expert. However, the sound from your youtube clip sounds like a heat shield issue. My 2002 Mustang GT did that. Not sure about the G though.

 

that definitely sounds like the catalytic converter heat shield. easy to get under the car and see. they're probably all rusted out and loose. mine did the same thing. had it happen on other cars i've owned as well.

 

post a longer video of that noise. its either the heatshields or the catalytic converter. but then again i would think the techs should have been able to identify that noise and gave you a nice upsell for the parts and labor.

 

It's one of these. My car made same sound when I took it in and ended up being the cats had gone bad but heat shield vibrations replicate a very similar sound.

 

That's the EXACT sound I have too, omg what a relief. I thought it was a rod bearing or something lol.. Although, I don't have cats so are there heat shields connected to the body itself? I'll just have to get under there with a 10mm and tighten everything up.

 

It sounds like that. Had my stomach in knots thinking about the possibility of that being the cause before my mechanic put my mind at ease and the dealership confirmed the cat.

 

My noise sounds like its coming from the centre of the car though. Also, I think a rod bearing sound gets worse with acceleration, whereas my sound seems to get quieter. Who knows though.

 

Yeah, rod bearings would be a constant noise and get worse over time so I knew that wasn't it after a few times BUT, when I heard it the first and second time I died a little.

 

I have my car booked in on June 13th with my mechanic (not the dealership). I will keep you posted.

 

Now that I know its probably something minor, I'll sneak under my car tonight or tomorrow and start checking for things. I'll also keep ya posted.

 

in the vid that you posted months back i hinted to you that it was your catalytic converter that was bad after watching it. this was verified later after you took your car into a shop to get checked out. you had a long enough vid plus it was shot from outside of your car. the op of this thread has a 7 second vid that looks like it was shot from inside the car. without climbing under the car and inspecting it is hard to tell. noises created by vehicles do travel to other parts of the car. it could even be caused by road damage on one component of the vehicle which is touching another part of the vehicle creating a rattle. i know one thing for sure, its that the noise is definitely not a rod knock.

 

Right. You were right about the cat being bad and I used that info when I brought it to my personal mechanic. They confirmed the hypothesis and from there, the dealership fixed under warranty. I shot my video from the wheel well of the driver's side; that's where it was loudest at the time of discovery. I didn't even think to check the passenger side to see if the noise was the same volume over thee since I thought it was a knock at first or a spun bearing. My only peace of mind was the fact that the sound dissipated as a drove; as mentioned earlier by someone- this sound intensifies the faster you go.

Circling back, the OP's video is shot from the inside of the car but I can recall when mine went bad, I could hear the rattling from the drivers seat with both windows up and windows down. I actually have videos form inside the cabin when I first noticed it. It wasn't until I closed in on the source of the sound and concluded it was in the wheel well vicinity that I posted my video. Figured this would help with asking other's for help diagnosing; which it did.

 

Not sure what the argument is here but regardless of who and how the video was taken, the OP's clip helped solve my issue. Mine would only make the sound pretty rarely but it sounded like internal engine damage so, for someone to captire the sound and post it was a big help for me. Thanks OP, was a big help bringing this to light.

 

No argument, I think castle was just pointing out the difference in my video from the wheel well and the OP's from the Cabin. I was just saying my video was from the wheel well because that's where I could hear it clearly; but it could be heard from the cabin like in the OP's video. I just figured my video help centralize the sound better than shot from the cabin where the noise could be from anywhere.

Did your's end up being the cat or heat shield?