[2007 G35 coupe 6MT 34k]
I hear a rattle when I engage 1st gear abruptly. Sound it's like hitting a loose part that is flexible so it wobbles/vibrates back and forth when hit. It's usually when I engage 1st but I have it happen while shifting at speed sometime also but it's always with bad shifts. I think it's from releasing clutch too fast.

1.5 years later I don't think it's any worst(as described above), but now occasionally I hear rattles while idling. It's not very loud, but if you are near a wall(sound bounces off wall and is amplified) you can hear it sometimes. Scary thing is it sound like a 4 cylinder engine that I blew before because oil leaked out. That car sounded great most of the time, then sometime it would rattle or "tinker".

Car drives great otherwise, just hard to get into 3rd sometimes if the RPMs are'nt just right.

What you think it is? Is this normal for Gs?

 

Nobody? Well.. any opinions on what I'm hearing?

 

I can't believe nobody else has had this problem. Now there is another symptom...of what I don't know. After Hard acceleration 6th gear became very difficult to enter and the gear lever slipped out of the slot a couple times while driving. What is happening to my car?

 

In a manual G35 odd sounds from the tranny and drivetrain are pretty common. It's not like a Honda, it's a physically linked drivetrain and it's going to feel raw and physical. If your tranny is making noise that you think is irregular or "destructive" get it looked at.

Mechanical music is normal..

 

OK, I did more research and found at least part of the problem. The rattle on shut down is supposedly normal for our cars. You can prevent it by pressing the clutch while shutting the car down. I just tested it and I've never heard my car shutdown so smooth!

Now...the popping out of gear and rough 6 gear engaging after hard acceleration thing...that's another issue. Also, I hear another rattle during idle sometimes that reminds me of my Celica when it's engine was dying(oil consuption left me on the HWY with NO oil!).

 

Yes, the transmissions and clutches rattle. A lot.

Some amount of notchiness in the tranny is normal when they are cold, once warm they seem to work pretty well.

My engine makes a lot of noise, but it hasn't broken yet and the noise has persisted for as long as I can remember. Every once and a while I think it is about done between the valve clatter and the light knocking coming out of the bottom (with the clutch depressed). Then I forget about it for a while until I go through a drive through and it all comes back to me. I keep the oil changed and drive it like I stole it - 122K miles and counting.