This problem has been irking me for a few months now.

VIDEO IS ANNOTATED: IT'S EASIEST TO WATCH AND UNDERSTAND WHAT MY PROBLEM IS.

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My car is a 2004 Infiniti G35 coupe, automatic w/ 80k miles.

When the car is in reverse or drive:
- Accelerating at low RPMs (maybe only 1st gear) - sound of metal rumbling/rattle
- Also when idling (you'll notice I shift into R, and the noise starts, THEN I move, noise continues)

Not sure if the problem is the engine, transmission, or if something is loose or needs to be changed.

Some other things I noticed. It's horrible when the car is cold. When it warms up and I drive it for about 15 mins, the sound is still there, but only right as I accelerate.

When I start the car and leave it in park, no noises. In neutral, it rumbles momentarily when I step on the gas.

It is hard to hear in the video with the wind and traffic sounds. But what I can gather it may be the exhaust rattling on something.

Yeah, I tried to keep the wind minimal.

If you turn the volume up, you can hear the rattling though.

So you think it's the exhaust?

could be shaft itself is bad or the shaft bearings are bad. I worked before on g35x and it had a simular problem, i discovered a nand brake cable was grinding against the shaft underneeth cause it was loose so that could be easy fix. Something ales could be loose too, hard to say with out checking all those things or even maybe brakes are grinding somthing.

It sounds fine to me.

I'll try and make another video, but today I checked it out and I'm 100% sure it's from the engine bay.

When I crouch near the wheel well on either side, I can hear it, even in Park.

Check your oil levels.

dude, i have the same thing... dont know what the hell it is.. only in 1st during cold starts for me.. somethings gotta be loose

My oil is leaking, and I've been refilling it for the last month a little.

I need to get under the car and check it out, but haven't had a chance.

ouch that looka like a cold day... it went down to 50F in south florida yesterday and ppl were freaking out lol

good luck with the problem, maybe make a video in an enclosed parking lot, where wind factor will be taken out and engine noise with be amplified by the walls

Sounds normal to me too, but have you check the exhaust?

RESOLVED: Apparently the exhaust shield was loose. My mechanic removed it completely. Thanks guys

Could you explain where exactly this shield is. I have an 04 coupe and I only hear this when accelerating, and the sound echos off of a divider or other cars next to me. In neutral revving does not make the noise, only as I accelerate.
Any help is appreciated. Thanks.

Ok is it the exhaust heat shield?!? Cuz I don't know what an exhaust shield is and my car has had the same rattling for 20k mi and me and my g buddies r curious of the source of the noise cuz we all got it :/

I have the same noise. Its the heat shield on the exhaust. You can just cut it off.