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91 C2 Hollow Ringing Sound in Engine Bay

 
Old 06-21-2015, 10:21 AM
  #31  
Goughary
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Originally Posted by J richard View Post
Any chance you can get it on vid?
I'm 1000 miles away from my car this week, so can't today, but yeah good idea. Not sure how I can do that, since it doesn't happen with the car idling. But maybe I can borrow a friend to stand on the road and see if he can pick up the sound on a drive-by...
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Old 06-21-2015, 05:16 PM
  #32  
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loose parts inside muffler or Cat?
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Old 06-21-2015, 05:45 PM
  #33  
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Originally Posted by jimq View Post
loose parts inside muffler or Cat?
Nope. Have had both g pipe and cup pipes on , and the cup pipe used a different cat. Also replaced my heat exchangers last year. So each component has been off. Never affected the sound.
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Old 06-22-2015, 04:56 PM
  #34  
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Originally Posted by chobe22 View Post
...My engine makes what I can best describe as a fairly faint, sometimes not-so-faint, ringing sound above the music of an otherwise strong motor.
The noise is a sort of hollow ringing sound, as if a relatively light weight metal ring 4-6" in diameter were vibrating within a thin walled pipe...
+1

Originally Posted by Mr. C4 View Post
Check the fan belt tension sensor, common culprit for "ringing" noises...
I hope not, I'm already replaced two!

Originally Posted by Fred, Long Island View Post
Fan pulley halves. If the rectangular hole in the center of the half wears, the pulley moves laterally and creates the ringing sound. Had it happen to my old SC. Not enough shims in the shaft caused the gap, allowing it to wear gradually until it rang.
This sounds like a good possibility...

Originally Posted by John Boggiano View Post
It's not a rattle..It's a ringing...
+1

But then this thread seems to change (from a faint ringing noise, now the focus is a rattling noise... Funny, I hear both noises coming from my car.

Originally Posted by Goughary View Post
old thread new bump -

I have this same noise - I am replacing my alternator this week - but I don't think my noise is the alternator - I think its more coming from the exhaust - but it's definately wierd - and seems to be worse if I am cruising slowly at 2500 rpm on a downtown street, sounds like a couple steel ***** in a can....hollow knocking type thing....anyone familiar with this noise?
I hear the same rattling noise, seems as though it's coming from the passenger side. I hear it at low speeds and it sounds like it happens after going over a small bump in the road, I thought it was loose bumper hardware shaking (rattling) back and forth after a bump. Everything I've touched seems solid, but I need to get it up on a lift...

Originally Posted by crg53 View Post
My first guess would be cat heat shield.
No cat, and it sounds like it's coming from the other side.

Originally Posted by Goughary View Post
Resurrecting an old thread. This hollow marbles in a tin can noise is still present. A lot of other guys have experienced this. It's not the alternator. It might be heat shields, but when the motor is idling, you'd think the noise would be worse due to more vibration, and it's less noise, not more...

Has anyone experienced this noise and fixed it?
I only hear the "hollow marble noise" when driving down a bumpy street at low speeds. Not while idling.

Originally Posted by Goughary View Post
...The frequency of the marbles in the can doesn't change with the rpm...but it does go away and return it seems.

Who else has the sound?
+1 frequency of the marbles in the can doesn't change with the rpm.

Originally Posted by J richard View Post
Any chance you can get it on vid?
I don't have a video (yet) of the marbles, but I found a video of the faint singing noise.
I heard it could be coming from the harmonic balancer? (I can see a slight wobble)

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Old 07-11-2015, 04:40 PM
  #35  
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Took a little while to capture the sound, it seemed that on the days I had a camera with a decent microphone ready the sound wouldn't be as audible. So here is what I have from three different days. Might have to turn up your volume a little.

Starts being distinctly audible around 15sec mark

Also, excuse the butt to the camera in the beginning, I had just replaced fuel filter and was checking for leaks.

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Old 07-12-2015, 08:58 AM
  #36  
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Alex,
I think I can here it in your vid. It's faint though.
Do you hear the same noise in mine above??
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Old 07-12-2015, 01:16 PM
  #37  
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It is tough to get a mic to pick it up well, but it is a faint sound for the most part in my case. Loudest at start up. I don't hear it in your video, to me it your sound is more a steady whine than a ringing.
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Old 07-12-2015, 01:50 PM
  #38  
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Ah....

Now you guys know you bought air cooled cars right?

I thought you had a harmonic banging or grinding, sounds normal to me. These things make those noises. Unlike a water cooled motor there is nothing to dampen all the mechanical internals. Just tap on the fan, shroud, cyl cooling fin, even a lwfw all make a particular ringing sound, the fan makes a howl that I've found particular to each car. I know you know all this but my point is these motors just make these noises, it's part of the charm, enjoy the drive
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Old 07-12-2015, 09:10 PM
  #39  
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Thanks Alex and J.

Like you said, these cars all make different noises (and each drive differently too). I can hear the ringing, tinny noise... but I guess it's all part of the cacophony of noise coming from back there.

With that settled, I'll start researching more about fuel lines... lol.
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Old 07-12-2015, 09:51 PM
  #40  
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To the other noise I was hearing....

I think this is the cause of the rattling noise I hear in town when I go over bumps in the road:

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Old 07-12-2015, 11:29 PM
  #41  
Goughary
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Default 91 C2 Hollow Ringing Sound in Engine Bay

I realize these cars make noise. I can't tell Alex if yours is like mine. So next NE9O meet we can have a listen...

My noise, and the noise that has been described, is not "noise these cars make". I've heard plenty that don't make the same sound.

Still hoping it's something easy or benign...so far the motor hasn't fallen out the back...knock on wood...
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Old 07-14-2015, 03:04 AM
  #42  
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Mine does it too.

I think it's exhaust related. Something just needs tightening up.

'94 C4
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Old 07-14-2015, 11:20 AM
  #43  
J richard
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in the clip above does the audible ringing sound go away when you close the door?
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Old 07-14-2015, 12:52 PM
  #44  
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Have you checked to ensure the fan isn't contacting the housing at any point?
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Old 07-15-2015, 08:47 PM
  #45  
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I do agree that these cars can make a variety of sounds, and smells in some cases, but I don't really the sound being there for the first two years I had the car. But as a new development, if I drive next to a wall or barrier on highway, I can hear a slight raspy tinkering, and in some cases it will increase with RPM. So I'm hoping its something loose, just can't wrap my head around what it could be. All exhaust clamps and mounts are tight.
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