# Ringing Noise while idling



## shadybab123 (May 9, 2006)

Hey Guys,
Just bought a 1998 Nissan Altima GXE (auto). The car only has 69,000 miles on it and I just had one of the pulleys replaced. I was sitting in the Carl's Jr. drive-thru for about 3 mins when all of a sudden I hear a very High-pitched ringing noise coming from my engine. The sound kind of reminded me of a 'FLATLINE' when someone on TV dies, but it was very loud. I revved the engine a little bit and the sound stopped for about 10 seconds and then it comes right back. It only makes the sound when I am idling, when I am driving it is completely silent. I've read online that it could be the idle air control motor... But I'm not sure. PLEASE SOMEBODY HELP


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## Pinny (May 1, 2006)

There is a dozen things that could be your noise but if you have had pullyes replaced occasionally they arent done up properly and things like the washers behind bolts eg. the crank bolt washer or the altenator pulley nut washer get loose enough to spin at low revs giving a sort of jingling noise but go quiet with revs.
A/C clutches make noises occassionally.
Most of the noises solenoids and management devices make happen fairly quickly to respond almost instantly to changes and typically idle up devices would make more of a whistling sound.
Some plenums in EFI systems whistle quite loudly even at revs.
Just one blokes thoughts thats all


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## davido (Aug 23, 2004)

*re*

hows your fuel pump? it might be harmonics. get you a stethiscope (sp) and do some listining around.


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## shadybab123 (May 9, 2006)

Don't need a stethoscope for this noise, it can get really loud. I noticed that if it started making the noise and I turned on the AC, after a second or two the noise would go away, making me think it was the AC compressor. But I noticed when I shut off the engine I hear the same whining noise as the engine shuts down. Can anybody tell me if these two noises are related (Possibly)? What noise could the engine down be. Its the same whining/ringing noise.


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## Pinny (May 1, 2006)

Dont suppose you are having any brake problems like hard pedal?
If the noise remains momentarilyafter the engine is switched off the noise you may be hearing could be the sound of a leaky one way valve or brake booster slowly losing its vacuum.
The noise going with the a/c could be to do with the manifold depression dropping with the little bit extra load.


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## FiredragonCT (Sep 1, 2004)

From the noise you are decribing it sounds like a loose part - I had the same problem and eventually found that my alternator fan (located directly behind the alternator pulley) had come loose - when the car revved up it rotated with the alternator - but at idling speed or switching the car off it would rotate at a different speed and cause the noise. When you switch the AC on the car revs a bit higher - resulting in the noise going away.

Might be a washer or another pulley as well - but definately sounds like something is rotating loosely on an axle of some sort


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