Rattle from under the 350z? how to fix it?
 

Hey guys, I'm having a annoying issue with my car. When the car is idling, I can hear a rattling sound from underneath the car.

It's a 2005 anniversary model 350z. I cant hear the rattle on a cold start (or maybe its just really faint). But on a hot day, after driving around for a while (or driven hard), when I park the car i can hear this rattling noise from under the car. Im guessing it could be an exhaust rattle.

Sometimes i hear it when parked on my driveway. And when parked on the streets, i cant hear it. So im guessing due to the road level, its something mechanical thats hitting something else.

From my google research i found out that it could be a heat shield rattle, or a CAT converter.

I took it to the mechanics and he said to find out if other 350z had a similar problem and how'd they fix it. And that he'd then go and fix it for me. He said "there is no use me charging you $80 an hour just trying to find the problem. It's better if you try to isolate the problem as much as you can and hence i'd charge you less". Good to know he didn't just want to chew my money! lol

Here is a video i recorded of the rattle. There are two DIFFERENT RATTLES i think. One while IDLING. and another when I turn off the car.

youtube.com/watch?v=97G12LT0mZE

RATTLE ONE Skip to 0:24 you can hear the rattle. And also at 0:50 to 1:00. Rattle one is not affected when i press in the clutch.

RATTLE TWO skip to 0.27 (when car turned off). and also at 1:00 (when car turned off). When i press clutch in, and then turn off the car, rattle two is very low then. Is this one just clutch rattle?

Both rattles seem to come from under the car, "center of front wheels, and then 10 cm back roughly".


THE SOLUTIONS?

Could it be this?
youtube.com/watch?v=OO03n22rwfg

For the rattle, skip to 1:10.

and this

youtube.com/watch?v=-tzQclY43IA

skip to 2:18. The sound is very familiar to this.


Anyone had a similar problem and fixed it? Any idea on what could it be? The noise is making me go nuts! haha

Thanks guys

My old si used to do this and it was the heat shield, just yanked it off and the sound went away

Good luck finding the rattle and I suggest you find a new mechanic.

lol put the car on a lift and move things around!

could be several things...

Your cats are now in your y-pipe.

Your y-pipe bracket is lose, may not feel it loose but once the car is on it's enough to vibrate it.

Your exhaust itself itsn't tighten...

Your y-pipe is slighty bent causing it to hit the frame...

etc....


can you replicate the noise with an action?

action meaning?

like is it only when your idling? You said it's quieter when the clutch is in, so could be time for a fluid change? Because the clutch is somewhat noisy but it's not described as a rattle...

I'm at work so can't really listen to the video i'll revist this at home

there are two rattle. One while idling and another when turning car off. I am not sure if its the same sound but they seem different.

Listen to the video on earphones and you'll see what i mean.

Thanks for the input guys.

Also check your lower control arm bushings. Especially the one that connects your lower arm to your frame. Both my bushings went at the same time and the sound was similar to mine. The aluminum arm rattling against the frame at idle was annoying as chit! Swapped out to some SPL bushings and away it went.

OP here. More info:

Rattle one is NOT there when car is first started up. Even when the car has been driven, and the weather is cold, the rattle isn't there. But it does happen when the weather is hotter. So i've guessing this is more to do with exhaust.

Rattle two is always there regardless of weather. Rattle is present even on cold start up.

OP here. More info:


another guy posted this on youtube. Rattle one that i get is veryyyyyyyyyyyyyyyyy similar to that. Sound same. Only heard at lower rpms.

Any idea guys?

of the 5 350z cars that rattled that i worked on, all 5 rattled from the heat insulation shielding that is screwed to the car around the catalytic converter. its suppose to sit up against the metal of the car but, some areas tend to just barely hover enough that if there is any engine vibration it makes that rattle. the simple fix was merely to bend the corners of the shielding enough so it would not sit close enough to rattle against the metal of the car.

RATTLE one seems to be heat related. I can only hear it on hot days. Now thats its cool in australia, I cannot hear it at all.

RATTLE two i think is clutch related. Because the rattle is affected by pressing in the clutch. I can still hear this rattle even on cold days.


Your referring to rattle one right?