Automotive

(Diagnosis) Need help to identify the source of a rattling noise?

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  • May 8th, 2015 11:51 pm
[OP]
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Aug 3, 2011
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Toronto

(Diagnosis) Need help to identify the source of a rattling noise?

My car is making a rattling noise, and I need some help to identify the source of this problem. I believe there are several car experts (or auto mechanics) on this board, so please help me out!

My car is 2007 Infiniti G35x (all-wheel drive; automatic transmission; VQ35HR engine).

I've been neglecting the issue (I know I shouldn't have :( )... and I think it's time for me to fix it. The car was problem free until this winter when I noticed two kinds of noise from the car.

One was a squeaking noise from the front of the car, and the second was a rattling noise coming from the underneath (most likely, but not 100% sure).

The source of the first noise was the serpentine belt. This problem went away when I replaced it with a new belt.

However, I cannot identify the source of the rattling noise. :cry:

The rattling noise appears when I start the car. After awhile (~30sec), the noise disappears. The rattling noise can immediately disappear when I shift the gear to Reverse/Neutral/Drive.

My guess is a transmission issue, but I hope it really isn't.







Anyways, I've recorded two videos to show you the problem.

Video #1 (from the underneath of the driver side)

[video]https://docs.google.com/file/d/0BzYjse8 ... EN2R2lQU0k[/video]

Description of the Video #1

0:08 - Driver enters the car
0:16 - Engine starts
0:19 - Rattling noise starts
0:37 - Rattling noise goes away
0:58 - Gear shifted to Drive
1:14 - Car on the lift ramps
1:17 - Gear shifted to Park (idling noise comes back, but the rattling noise doesn't)
1:37 - Engine turned off
1:40 - Parking brake engaged
1:42 - Brake pedal depressed
1:46 - Driver exits from the car



Video #2 (from the Passenger side)

[video]https://docs.google.com/file/d/0BzYjse8 ... FdOSGExNGM[/video]


Description of the Video #2

0:08: Engine starts
0:11: Rattling noise starts
0:16: Gear shifted to Reverse (and the rattling noise goes away)
0:18: Parking brake disengaged
0:30: Gear shifted to Park again
0:40-0:45: Sharp noise unrelated to the car (Removing the lift ramps)
1:25: Gear shifted to Reverse
16 replies
[OP]
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Aug 3, 2011
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Not sure why the video tags aren't working....but both are 720p MP4 files.

Anyways, thanks in advance for helping me.
Deal Fanatic
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Nov 24, 2012
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Space
Misfire? Injector? Bearing? Heat sheild ( doubt this one ). Does the sound only happen on cold start or when the cars been sitting a while? Any engine light on?
Sr. Member
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Aug 27, 2010
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Did you check the area where the flex pipe joins to the catalytic converter? I know that the rattling noise that was coming from underneath my car was because that area had rusted out. I am not a car expert, so I am just taking a guess here!
Deal Addict
Nov 21, 2008
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If that sound came from your transmission, you'd be driving a Lada.

I've had similar sounds from a rock caught between shield and converter, and also with a loose heat shield.
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Aug 12, 2007
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have you checked the oil levels in the transmission? taken it in for transmission service? sounds like cavitation in a fluid pump. maybe that's just because of it being a video and not me being there in actuality.
Member
Jun 9, 2011
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Arabidopsis wrote: Description of the Video #2

0:08: Engine starts
0:11: Rattling noise starts
0:16: Gear shifted to Reverse (and the rattling noise goes away)
0:18: Parking brake disengaged
0:30: Gear shifted to Park again
0:40-0:45: Sharp noise unrelated to the car (Removing the lift ramps)
1:25: Gear shifted to Reverse
I would bet on engine mounts or anything along the drifeshafts (worn mounts, worn u-joint on the rear driveshaft).
Sr. Member
Aug 5, 2012
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MISSISSAUGA
My guess is a worn out ball joint on the driver side.
Member
Jul 19, 2007
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Sarnia
I bet its a heat shield and the noise goes away after the metal expands. Try putting a screwdriver between the pipes and heat shields and pry a little and see if the noise goes away or changes.
[OP]
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Aug 3, 2011
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Solsearchin1 wrote: Does the sound only happen on cold start or when the cars been sitting a while?
Yes and no. I originally thought it only happened on the cold starts (at winter time). But now it's also happening when the car was parked for ~20minutes (after driving for ~30minutes).
Solsearchin1 wrote: Any engine light on?
No light on.
[OP]
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Junerose wrote: Did you check the area where the flex pipe joins to the catalytic converter? I know that the rattling noise that was coming from underneath my car was because that area had rusted out. I am not a car expert, so I am just taking a guess here!
robertz wrote: If that sound came from your transmission, you'd be driving a Lada.

I've had similar sounds from a rock caught between shield and converter, and also with a loose heat shield.
tyweed220 wrote: I bet its a heat shield and the noise goes away after the metal expands. Try putting a screwdriver between the pipes and heat shields and pry a little and see if the noise goes away or changes.
I'll check the heat shield. I saw some serious rusts there, so it is possible that a few clamps might be loose. Thanks.
[OP]
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Supahhh wrote: have you checked the oil levels in the transmission? taken it in for transmission service? sounds like cavitation in a fluid pump. maybe that's just because of it being a video and not me being there in actuality.
Checked the ATF level. The level is good. Color is clear red (good sign). No burned smell.
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May 10, 2005
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vik56in wrote: My guess is a worn out ball joint on the driver side.
Really, the car is not moving...how could the ball joints make any noise :facepalm: Time to learn a bit about cars.

Anyway, the fact the you can make the noise go away may indicate that something is loose, like a heat shield or a connector pipe. When you put the transmission in gear, you "load" it up and that may be enough to tighten up whatever is loose.
Get a big screwdriver and, with the metal end, tap on any piece of metal under the car, it should sound solid, if it resonates, that is an indication of looseness or a crack. I call this a 'tap test". I have used it many many times and it works for finding loose metal. If you do not have a big screwdriver than a small hammer will do. It has to be something made of metal so you can get the sound, if you use plastic, it is too soft and will not transmit the right sounds.
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May 2, 2010
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Good video. Yeah sounds like heat shield to me. The noise is definitely coming from outside of components..
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Nov 13, 2010
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tighten the metalic heat shield......
[OP]
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Aug 3, 2011
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Thanks everyone for the help. It was a loose heat shield causing the noise. I tightened it up with a hose-cramp, and the noise went away! I`m so happy :D
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Luckily it was such an easy fix. It definetly didn't sound like that! That would have been my last choice lol. Goes to show you that without seeing the car all we are doing is guessing online. Glad you got her fixed up.

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