whine at idle

GeorgeC

GeorgeC

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GeorgeC
I hear a high pitched noise between 700-800 rpm. I initially thought it was electrical but I hear it even with the avionics off. Toggling the alternator field switch had no effect. Happens if the engine is warm or cold. As soon as I bump up the rpms, it goes away. O200A. Anything to look for? The right seat is empty, so it's not the passenger...
 
Do you hear this noise with and without headsets on? Do you have ANR headsets, are the batteries fresh? Is the tone of the whine steady or does it go up with increased rpm?

Lots of questions but regardless of your answers at the moment I have no clue....

-Skip
 
maybe when you make that first video we can actually hear what you're hearing...…..
 
Induction leak. Check the gaskets at the carb and cylinder intake flanges, and the hose clamps. It will whistle because the manifold pressure is low at idle (high vacuum is another way of saying the same thing), and opening the throttle changes that and the whistle stops.
 
It's more of a whine or a squeal than a hiss or a whistle. It does idle a bit high though, 7-800 instead of 5-600, which I suppose an induction leak would contribute to. Would such a leak show up on my MP gauge? IIRC it's below 15" at idle.
 
GeorgeC said:
Would such a leak show up on my MP gauge? IIRC it's below 15" at idle.
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No, it would not. The MAP is sensed from one cylinder. A leak would just be pulling air from source other than the carb.
 
GeorgeC said:
It's more of a whine or a squeal than a hiss or a whistle. It does idle a bit high though, 7-800 instead of 5-600, which I suppose an induction leak would contribute to. Would such a leak show up on my MP gauge? IIRC it's below 15" at idle.
Click to expand...
A loose gasket will squeal like the reed on a saxophone. It can make plenty of noise.
 
GeorgeC said:
I hear a high pitched noise between 700-800 rpm. I initially thought it was electrical but I hear it even with the avionics off. Toggling the alternator field switch had no effect. Happens if the engine is warm or cold. As soon as I bump up the rpms, it goes away. O200A. Anything to look for? The right seat is empty, so it's not the passenger...
Click to expand...

Did you recently have engine mounts replaced? Is the flywheel clear of all cowling? Don't ask me how I know this.
 
Timbeck2 said:
Did you recently have engine mounts replaced? Is the flywheel clear of all cowling? Don't ask me how I know this.
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He has an O-200. It doesn't have a flywheel up front like the Lycoming.
 
weirdjim said:
I hear a whine around the house when I'm idle also. :cheerswine:
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Is that from the wife continuously asking when we are going to leave? Did you lock the car? Did you lock the house? Do you think I’m pretty? Can you work any overtime? Have to called your mother?
 
Sounds expensive, whatever it is. I am on the induction air leak side. You may or may not have noticed a difference in leaning due to more air in the system.

Unless it is you being impatient to fly, 8n which case, just stop making the noise.
 
I finally figured it out. It was warm today, so I started up with the window open. Upon hearing the whine, I reached out the window and put my hand behind the venturi... behold, the noise stopped.
 
GeorgeC said:
I finally figured it out. It was warm today, so I started up with the window open. Upon hearing the whine, I reached out the window and put my hand behind the venturi... behold, the noise stopped.
Click to expand...
I've seen that, too. On an old 172. Took me a while to track it down. If I put one finger between the aft inboard edge of the venturi and the side of the airplane, it would stop.
 
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