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High-pitched buzz/whine when engine is stopped

28318 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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mine does this high pitched buzz too, i found it to be the pump at top of engine bay behind the block ( belt side ) at the side of the ECU and it's belt driven, you can feel it buzzing when you touch it, don't know what it is or what it's for as there's nothing in the manual, can anyone elaborate on this, cheers
 

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I think is this ...:)

Turbocharger “Cool Down”
This vehicle is equipped with an after-run pump to cool
the turbocharger after the engine is shut off. Depending
on the type of driving and the amount of cargo, the pump
will run for up to 10 minutes after the engine has been
shut off to circulate coolant through the turbocharger.

Although the pump is rubber-mounted for quiet operation,
it is normal to hear it running during this time.

...info from a Abart manual...not 100% sure:
 

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For anyone still wondering what this sound is:

Visit your local autoshop and order an aircon service. The "eletric whisteling" noise is caused by this.
I thinks the explanation was low level of fluid.
Have done it twice now and it works :)
 

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My 2016 Giulietta did this buzzing/whining noise. It quietened down when I locked the doors and then got louder again. Didn't use to do it but started over Winter and continued until a few weeks ago when I had the innoperative aircon looked at & the dealer re-charged the refrigerant. God knows how it's stopped it making the noise, but it's quiet again now, so I'd agree with those saying it's linked to the aircon, but I've no idea how or why.
 

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Hi all, so for anyone still wondering what this is. I have found exactly what causes this noise, what it indicates and how to fix it:

The noise comes from the AC pump relaxing with less/without gas.

So once you start hearing this noise, it means your air con is going to fail soon.

The way to fix it is to have the gases refilled by a professional and take the opportunity to fill it with a fluorescent agent to look for leaks. If the car's old, then it may just be normal loss through old rubber seals. As long as the leak isn't too big, you should be good to go for a few more years without a refill.

Hope this helps.

Edit: Fixed the running error with relaxing
 

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Stelvio Veloce
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Hi LumiUmos, how do you come to this conclusion? Once the engine stops the AC compressor is not being driven by the auxiliary belt. I have a 2010 car and the buzizng we are all talking about is from the ECU on the bulkhead. If this noise happened every day from the AC system with a leak there would be a day when it didn't happen I've had my car now for 7 years and it does it every time we turn off the ignition. Also to quash other opinions there is no coolant pump running to cool the turbo on any Giulietta that I know of upto the 2016 models.
 

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So my noise sounded pretty Electric and today I went to the garage to fix my AC which wasn't cooling anymore. I've had that noise since November and you can easily check if it comes from the AC pump by putting your hand on it.

So I mistakenly said that it was due to the pump running, but I meant it is due to it relaxing when the car shuts off. When relaxing with gases there is no noise (it hasn't happened since the gas refill). But if the pump relaxes without gases you will be able to hear the noise.

Also the noise happens because the system has no gas left, the leaking is not the noise. As long as you're above a cetain gas threshold you will hear nothing and right after you have insufficient gas the noise starts.

Now we may be talking about two different whining electrical sounds, but last time I found a thread such as this there was a video from someone attached and it was the same as mine. I'll post a link hear if I happen to find that video again.

Now there may be some electrical component to the noise (maybe a solenoid discharging because it can't do it mechanically against gases or something) because I also noticed that it could get louder when using my central lock.
 

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Giulietta JTDm-2 170 TCT 2012 (MY2013) Sportiva
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I have it too but always thought it was normal, if you listen to it long enough you will also hear a sort of clunk at the end just before the whine stops. I always thought it was the vacuum pump levelling pressure out.

however I am due an ac refill so interesting.
 

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I had this whine / squeezing noise too - after driving, and engine stopped.

I have just had air-con serviced and re-gassed and it has magically now stopped.
Yay! I had it for about year, so very pleased that worked! :)
Same here. I initially assumed it was a turbo timer but it stopped the day I had my aircon (which was at 25ish% if what it should have been) recharged.
 
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