My 2008 G37's exhaust is very loud on cold start up. I understand early G37's had a bad muffler and theres a TSB to replace it. My car is out of warranty though, is this problem more of an annoyance or will the sound get worse and make the car loud while driving?

 

Dude...thats just the car warming up. Happens on all cars.

 

No this isnt the regular warm up noise. It is very very loud on cold start up, I dont think its normal and I know theres a TSB. My only question is will the muffler deteriorate and get loud while driving if I dont replace it?

 

Could be an exhaust leak somewhere. I remember installing HFCs on a friends 370z a couple years ago and we forgot to rebolt the flanges on the mid-pipe and axel back and it was crazy loud once we started the car up. Once the car warmed up it quieted down and you couldn't even tell.

 

how loud you talking about? Be better for a video. I know G37 coupe startups are pretty loud..

 

Its making a loud rattling noise at start up, cant believe none of you know about the tsb on the muffler. I just want to know if it will get worse then that. The youtube link is just like mine.

 

Shouldn't get any louder the car already 5 years old

 

Sounds normal I have an 08 coupe and when the muffler went bad it wasn't louder the problem was it would rattle like some thing was lose inside the muffller. You could hear it even when the car was warmed up and at idle. I got another muffler from a guy who had a 2010 coupe, because he had got an after market muffler, and the sound was the same minus the rattle. The difference in mufflers between the early model and later model was the mufflers where stamped and the later models where welded so you would not get the rattle noise on them.

 

I think it sounds like a normal cold start, if it was an exhaust leak I think you would hear a ticking sound. Not always.Now on my Altima I had before, the mid pipe went bad and it would rattle on a cold startup and quite after it warmed up. Nissan wouldn't repair it under warranty. The part before and after was covered but strangely not that part. Even called Nissan North America which is right down the street and they wouldn't help.

 

I liken the sound to a Mercedes diesel from the early 80s. Mine makes this sounds as well (2013 sedan) when it initially starts up. Once the idle drops, it disappears. My 2004 did not do this, so I'm not sure what changed, but I think the sound is normal.

 

it's not that we don't know, it's that you weren't clear enough about what you were saying. If you said exhaust rattle then it might have rang some bells rather than saying your exhaust is loud...

 

that sound is 100% normal.. I have had 2 g coupes and they both do the same thing every morning! You really shouldnt rev your car up until it is at operating temp.

 

That's if the leak is at the exhaust manifold...

 

I can't view/listen to the video while at work but my exhaust was extremely loud at start-up. My co-worker even said it sounded like a beastly race car.

Well, it turned out that my "non-modified" car (which I purchased used) was indeed modified and the resonators were taken out. I have an OEM IPL exhaust now and it's not very loud at all on a cold startup.

You could always inquire about the exhaust TSB as my car is out of warranty but still had some warranty work done. Or it could be the unlikely chance like mine where the stock exhaust was modified in some way.

 

My new '13 G37s sounds like an old beater with a hole in the muffler when started cold. It lasts several seconds and then suddenly changes to a normal exhaust tone. My guess is there's a temperature actuated valve somewhere that opens when the exhaust cools to minimize condensate build up. Never had a car do this before.