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High-pitched buzz/whine when engine is stopped

28317 Views 72 Replies 34 Participants Last post by  CuoreAlfa
Hi all,

I'm a fairly new owner of a '62 plate 170 TCT diesel.

I've noticed that when I turn the engine off, there's a high-pitched whining/buzzing noise coming from the engine bay somewhere. It doesn't matter if the engine's been run for a few moments or a half-hour or more. Is this normal? Has anyone else noticed it, and if so does anyone have any idea what it may be?

Just curious...

Thanks in advance,
Biggsy
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Itis nothing to do with your aircon, the ECU's buzz like mad for about 2 minutes after engine off, my Stelvio does the same thing, had it on the Giulietta and the Giulia!
When i got my 2015 car 2 years ago i had this buzz every time i switched the car off,i managed to find that it was coming from the bottom of the engine on the belt side,i found online somewhere it was because the air con needed recharged,had that done and not heard it since,i still occasionally get a buzz when switching off but this is around the top of the engine so probably ECU's.
 

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Stelvio Veloce
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More refrigerant would mean higher pressures and more chance of a leak. Less refrigerant would mean lower pressures and lower velocity leaks that would be so hard to hear, so I can't understand why you all think its an aircon issue?
 

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Possibly because there are numerous posts in the forum stating that a similar noise disappeared after topping up the AC. I've not experienced it and I'm not sure if it is compressor feature or a symptom of low refrigerant causing a noisier equalisation of pressure. Not sure how long the noise lasts.
 

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Okay so if your aircon needed recharging did anyone fix any leaks or seals or did they just add more refrigerant?
Hi,no leaks,just needed a recharge,probably the first time it had been recharged,i must admit when i read that's what the problem could be i was a bit sceptical that it would work but it did for me and the buzzing before hand was easily found to be at the bottom of engine.
 

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I can confirm a recharge of refrigerant will fix the buzzing sound, heard after a few minutes switching off car. I had recharge done and the sound has never reappeared. The leak is from the front seal of the compressor as with all vehicles with A/C, if not regularly run. Every week for at least 10mins you should switch on your A/C to prevent the seal drying out and contracting. I had not been able to drive the car for long distance and only twice a week at most for over a year and never used the A/C or climate control (obviously runs A/C). I should have known this from my previous life but it wasn't top of mind.
 
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