I had a scary moment as my car had this loud rattle under hard acceleration. As I hit the accelerator on a freeway on ramp I heard this rattle in front of me on the other side of the firewall in the engine compartment. It only made the noise at high RPM 6k +. Pretty loud though. My initial concern was some sort of oil starvation. A couple of months ago I noticed my oil was low a couple of weeks after I went in for servicing. I had heard about the oil loss issue and was checking on it. I took it to the dealer they said it looked fine, but that I should bring it in for monitoring. I also noticed that the Infiniti emblem was broken off my engine cover. They replaced that. I started changing my own oil after that and never had the problem again. It's never been low between changes. Anyway I pulled over and checked the oil after hearing the sound, perfect. I didnt see anything else so I drove it some more. Everytime I brought it up past 6k it would make the noise. In normal driving I don't rev it up that high (it's an automatic), so I have no idea if this had been going on for a while. I usually have music playing and under normal driving I don't take it past 6k rpm often. I took it to the dealer. My service rep said there is a service bulletin out about silicon/plastic peices in the heater core rattling around when the car is at high RPM's. He sat in the car , we revved it up and the rattling noise was there every time. They gave me a loaner for the day. They wanted to check it all out. I came back later and no more noise. It was indeed material in the heater core. They back flushd everything and got the excess pieces out. I asked if something broke inside and they said no. Its excess materialin some cars. Its been a few days and the sound is gone. No other issues. The car is a stock 2008 G35S sedan. The only mod is Tanabe springs and BFG tires. The dealer was Riverside Infiniti. If you hear the noise take it in. If you dont hear it go out and check.

 

If it was before you car is completely heated up, it could simply be your heat sink(?). Like that with most cars. Hasn't expanded yet and has a slight rattle sound if you gun it before the car is heated up.

 

Why in the world would you continue to take it up to high rpms with a rattle noise without taking it into a shop to have it checked out? You may have what is minor issue that will turn into a major one.

 

Is this the same?

http://x.infinitihelp.com/forum/loca...atid=87&id=178