DreamTheater27

Hey guys! Owner of a 2013 G37x Sedan and am having an issue I haven't heard on any other G37 but I wanted to get some feedback from you guys and see if anyone else has had a similar issue.

To start with, this issue only populated once I did a muffler delete to a straight pipe from the end of the mid pipe to the tips, nothing much but regular piping and solid. I should mention that I currently have 91k miles on it. I started to hear minor rattles at certain RPMS but I could never pin it down, it wasn't consistent, and I wrote it off as "resonance". The sound has gotten progressively worse, and we'll fast forward to last week. I noticed my car suddenly got incredibly loud, I knew it was some sort of leak, sure enough my Y-pipe was completely cracked through, and had to be replaced. I replaced it with a Megan Y-pipe and now it's back to how it was before, but that rattle is back harder than ever. It doesn't happen on cold start ups, in fact, it takes about 5-10 minutes of driving to kick in, but once it does, it's super consistent now. In gears 1-4 I can really hear it every time at about 2800-3k RPMS, with it appearing at 1.5k RPMS in overdrive gears. There's no way this is resonance, something is clearly rattling or vibrating causing this noise. I have removed practically every bit of heat shielding I can, and have thoroughly banged against everything underneath to make sure nothing is loose. The initial response from the G37 reddit community is that the cats are going bad, I'm inclined to think this may be the case. I will include a series of short clips of this issue, a 30 second clip of it parked where I am able to reproduce it easily, and then a clip of night driving where it's insanely evident.

I hope someone here has seen this before and can help me get this resolved as it makes it completely embarrassing to drive.

Thanks!

Playlist of small exhaust clips: Terrible vibration while parked: Night driving:

PNW_IPL

iTrader: (5)

I dont think its the cats. I think theres a heatshield touching somewhere. It also sounds like a loose bolt rattling. Check heatshields and cat to header bolts and cat to Y pipe bolts.
Report back and advise.

slartibartfast

iTrader: (7)

Rotting heat shields are very common on the AWD cars.

DreamTheater27

DreamTheater27

DreamTheater27

@PNW_IPL Looks like everything I bang on under there around the cats feels solid. I can't visually see or even feel anything loose. I removed all heat shields that I could, under the mufflers, mid pipe, cats, etc. I think the honeycomb inside the cats is loose and bouncing around. It is hard to say though, definitely needs 5 minutes of warm up driving before it starts to happen. I posted a video of the underside and of me revving it after it starts to act up. You can hear it consistently at 3k RPMS

DreamTheater27

@slartibartfast While they definitely are rusting and not the best looking, I can't really say that this is the issue after really trying to move them

NealP

Make something like this and maybe you can isolate where it's coming from.

slartibartfast

iTrader: (7)

Someone recently reported their windshield washer reservoir as a source of noise. Check it, too.