Hi everyone

I have a 2007 G35 coupe that makes a weird metal rattling sound in certain RPM's. Usually it is between 1.5 to 2K RPM's. The noise only occurs when accelerating and in motion. If I put the car in neutral or park, there is no metal noise at all. I only use premium fuel from Chevron, checked my engine oil and its fine. I have gotten under the car many times, and do not see a loose heat shield at all. This sound is driving me crazy!! Here is even a video that I recorded of the noise. Please help!

 

Is the noise happening in the engine bay, or somewhere else? Pinpointing that could help. Check your exhaust midpipe; it's possible that it's contacting the cross-member whenever you accelerate/have the engine at certain RPM's and the motor/exhaust move enough to contact. Had that happen with an aftermarket exhaust, but it could happen with stock if your motor mounts/exhaust hangers are worn enough.

Alternatively, check your serpentine belts. Mine made a noise similar to rod-knock when part of it tore (was still connected, but flapped every time it went around a pully). Just throwing out some ideas.

 

Thank you for the suggestions! The noise is not coming from the engine bay. To best describe it, the noise seems to come from underneath the car, near the transmission/cross-member area. My friend when he is in the passenger seat hears it on his side of the car, and I hear the metal rattling noise on my side of the car. I have noticed that I HARDLY hear the rattling noise in the morning (cold start), and after driving for 15 minutes on the freeway and then driving on the street the noise is very faint. Did some testing yesterday, if I accelerate very very slowly to 2K RPMS the noise is very faint/non-existent, but if I accelerate with more gas then everyone can hear the rattling noise. I will check the mid-pipe and the rest of the exhaust system to see if it is hitting anything.

My driver side lower balljoint needs to be replaced, but I doubt that is the cause for the noise?

 

Check the cat heat shields.

 

^^^