Strange "buzzing" sound from motor space, Citröen C5, 2.0 HDi, 16V, 160HP, 2011

[claudiob]

Regards to all.
I drive over 10 months Citroen C5 2.0 HDi 160hp, made in 2011, with automatic transmission and Hydroactive 3+ suspension.

Everything is superb, don't have any issue and car has real 137.000km.

Since a few weeks ago, when auto is hot, ie. after relaxed driving an hour and a half or two, sometimes I hear a buzz, from under the bonnet or below the middle of the windshield, which is clearly heard when you raise the hood. Please note that the car driving around big city in europe, where only pensioners ride possible, ie without the rampage and foot on the throttle.

I recorded a video tonight with buzzing sound:



I would just like to mention that suddenly there is no noise, but I guess my Samsung S6 microphone is turned so that the software of the phone annulled the sound ... buzzing was mostly hears constantly until the engine was shut down. I do not use the air conditioner ... so that is not a fan of air conditioning or something similar

Once again, let me emphasize, the buzzing is heard only after an hour and a half, maybe two hours of driving, let's say, that's min 90 minutes relaxed driving. If I drive 10-15 minutes, there is not any buzzing sound ...

Thank you all for reading this messages!

[GiveMeABreak]

Err not sure what's happening with the video - but it's only showing Star Wars Trailers and Srreen Junkies???? Regardless if it is restarted!

[myglaren]

Works fine for me Marc - use adblock if you aren't already.

[GiveMeABreak]

Yep got that on already Steve - where would we be without that! Closed the page and it works now! Still, an odd noise - tend to want to say a relay is on the way out, or secondly that is sounds very close to the BHI Hydraulic pump. Can you get it checked with a Lexia where you are Claudiob?

[white exec]

Even if you don"t use the AC, cooling fans may still cut in (first at slow speed) after some hot driving.
Does sound like something rubbing on the fan 'blades' - maybe a stray cable-tie, or a twig, or...
You could try to check this out by turning on the AC: fans should come on immediately at slow speed.

Noisy alternator? Heater blower?

[claudiob]

Guys, thanks for reading my theme.
I tried AC fans first time i hear that sound, but no, thier sound is diferent.
Also, there is no point for service, if simptomps can't be easily reproduced. Buzzing sound is heard only after long ride, and not every time... I will order Lexia, it's not expencive...
I thought, maybe some repair men would know what is hiden behind that plastic and what could produce such noise...

Thank you guys.. i hope some one will see this video and will know.

[white exec]

Does C5 have a vacuum pump for EGR, like XM? These can go buzzy with age.
Electric hydraulic pump?
Just guessing...

[GiveMeABreak]

They are electronic ones on later models, so not sure.

[Mandrake]

Have you tried using a mechanics stethoscope (also known as a very large very long screwdriver held against your ear ) to help identify the source of the noise ?

In an engine bay full of noise this can sometimes be the only way to identify where a noise is coming from...

[old'uns]

mine does it too...very low volume, sounds like it's from somewhere around the LDS reservoir?
do i care? no
maybe it's another thing to add to my list of 'woes'

[myglaren]

Just turn the audio up a bit

[old'uns]

just makes the speakers crackle

you don't hear it when driving, only when stopped, ignition off and very little background noise

hopefully it's about to catch fire/blow up and so will stop me spending, sorry, throwing money at it