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'84 300DT, '97 S320
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Discussion Starter · #1 ·
When I was test driving our S320, to present day, there's been a cricket/chirping/whistling sound. It's rpm-related.

Usually most noticeable when driving up to 30 or 40 mph, or more, then letting off the gas pedal, and when the rpm's drop from 2400 to 2000, there's the sound. Always in that range. Appears to be coming from behind the glove box. Maybe an idler pulley ?
 

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W220 S320 CDI 2005; W140 S280 1994 (Sold Nov. 2012)
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867 Posts
Is it still there if you turn off the a/c unit - i.e. blower not operating?

Mike
 

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nothing broken. finally!
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2,619 Posts
blower motor
 

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1999 Mercedes Benz S420 45K miles, 2007 Acura MDX, 1997 Honda Del Sol
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84 Posts
No big deal. Just lube the blower fan motor. I just did that last weekend, no more noise
 

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'84 300DT, '97 S320
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682 Posts
Discussion Starter · #5 ·
Noise is still there with fan/climate system off. Refining my original post, the chirping is closer to RPM 1800-2000. I can sesaw the RPM's back and forth through 2000 and the chirp is always there. I don't seem to hear it when accelerating normally, I guess because it passes through that RPM value quickly.
 

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1995 Mercedes-Benz S420 (W140), 1997 BMW 740iL (E38), 2011 C300 Luxury (W204)
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1,314 Posts
Noise is still there with fan/climate system off. Refining my original post, the chirping is closer to RPM 1800-2000. I can sesaw the RPM's back and forth through 2000 and the chirp is always there. I don't seem to hear it when accelerating normally, I guess because it passes through that RPM value quickly.
I get not a chrip, but a "rattle". Like something is loose and rattles about that same exact RPM you mention. Instead of being on my glovebox side, it is towards my drivers side speaker vent/telephone speaker area. But my driver side is on the left hand side. Is your steering wheel on right hand side? If so, maybe we are experimenting the same thing on the same side of the car since your glovebox side = my driver side.

Anyways, more about the sound. It only occurs in the range of 1800-2000 RPM, more evident when slowly accelerating through that RPM range. I can hold it steady around 1900 RPM with cruise control on and the rattle will be continuous. Is yours similar?


EDIT: Nevermind, I think you are a Left hand side driver as well. This rattle annoys me, but with low music on I never hear it.
 

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'84 300DT, '97 S320
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682 Posts
Discussion Starter · #7 ·
Yes, LH Drive. Mine really is very cricket-sounding. Gotta record it. If I try I can make it somewhat continuous, yeah.
 

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W220 S320 CDI 2005; W140 S280 1994 (Sold Nov. 2012)
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Yes, LH Drive. Mine really is very cricket-sounding. Gotta record it. If I try I can make it somewhat continuous, yeah.
Is the chirp there when the car is stationary and the engine revs in the 'critical' range?

Mike
 

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1998 s320
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I had a strange chirping noise that came on around 40-50mph, turned out to be a cracked exterior mirror seal, the black vertical molding between mirror and body. Pressing the mirror slightly forward made the noise go away.

Jan
 

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1995 Mercedes-Benz S420 (W140), 1997 BMW 740iL (E38), 2011 C300 Luxury (W204)
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Is the chirp there when the car is stationary and the engine revs in the 'critical' range?

Mike
Mine does not make the rattling sound if car is not moving, ie neutral or park.
 
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