C4 Cactus 1.6 BlueHDI 2014 whining noise

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martin_b
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C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

My car has this strange high pitched whining noise coming when driving at around 100-140 km/h. I am pretty sure it's something resonating, a wind noise of some sort. At first I suspected the turbo, but I don't think that's the case. My mechaninc has checked the turbo. There's no slack, the car doesn't use any oil at all, exhaust is clear. We removed the DPF and had it profesionally cleaned just to rule that out. After 200.000 km it was 47% full. When it got back it's 0,9% full according to the computer.

The sound comes only when driving in windy conditions with wind hitting the car from the front/right. It doesn't change when I switch off A/C, if I set it to re-circulation or any other combination of settings. I have tried removing the little "pan" which is under the fresh air intake where the cabin air filter is located. I have tried removing the engine cover and driving without. All this does nothing. I am pretty sure it's some sort of resonance. My daughter filmed a video while the noise was present the other day. Please have a look and let me know if you have experienced something similar. Comes on at about the 10 second mark.

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GiveMeABreak
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by GiveMeABreak »

Hi Martin. It doesn't sound engine related to me. It may be the wind at speed entering the air intake and causing some whistling. Possibly some object / debris stuck in the air intake grille or that has gotten into the air distribution system for the interior of the cabin. If you manually switch the fans off and switch to recycling, does the noise stop? I was thinking another cause may be the blower motor bearings whining.

It may be a process of elimination, checking window and door weather strip seals and exterior trim for loose parts etc.

Regarding your DPF - don't forget that the DPF will constantly show its status as it fills up. The percentage is not related to the overall blockage of the filter. This percentage reading will increase over several hundred kilometres until a regeneration is triggered and then the percentage falls back, then the cycle repeats. So if the DPF has been cleaned, I would expect to see a low figure initially, but that will start to increase and fall back again after each regeneration.

So that doesn't really tell you anything except the filters status at the time a diagnostic is run.
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

Yes, I agree it doesn't sound engine related. Posted this to find out if anyone experienced the same. It could be a million things.
As I said, I have tried switching fans off and changed to recycling. Doesn't make a difference. The sound comes on only under certain speeds and wind conditions. Not when I drive about on country roads which is most of my driving. The sound comes from the middle/right part of the car, that much I can determine.
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GiveMeABreak
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by GiveMeABreak »

That would make sense relating to the air intake and ducting. When were the pollen filters changed last? A lot of bugs, leaves and other debris can accumulate in the housing once the filter gets blocked.

Pollen Filters
martin Pollen Filter.PNG

Air Ducting (You only have (3), (4) & (5) on this diagram.
martin Air Channels.PNG

Air Intake
Martin Air Intake Manifold.PNG
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

I replaced the pollen filters about a week ago to see if it would make a difference. The old filters looked brand new but I changed them anyway. No difference.
I will have a look in the ducting with a small camera I use for inspecting piping in a different context. The air-intake system at the front (6 in the last picture) is a bit loose - as is all the pipes that go to the air-filter box on top of the engine. I have seen this being broken on lots of Cacti because mechanics break it when changing air filters. Could be that too. I can gather that it will be a lot of detective work to solve this! Hoped somebody else had experienced the same :)
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GiveMeABreak
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by GiveMeABreak »

Anything loose like plastic cable ties poorly tied (which they love to use when they break the clips) are a good one and any loose items can cause the whistling at speed, or any housing not properly secured (again could be a clip missing), so good luck with the investigations (or buy some headphones!) :-D
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myglaren
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by myglaren »

Or as my brother says, turn up the radio.
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

Thanks for the suggestions guys :)
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by Rp0thejester »

Sounds like Morse code, do you have a roof rack? It's definitely air making that noise, definitely check windows and seals also body panels for debris
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

No, I don't have a roof rack. It sounds very distinct as if it comes from the middle/right side of the car. It doesn't appear to be related to the air ducting as it's pictured above but rather the air intake to the engine. Next step is to disassemble the entire intake and carefully re-assemble ensuring everything fits as it should.
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by Rp0thejester »

If it was anything going through the engine bay it wouldn't sound like that. You wouldn't notice it over the engine noise. It's an outside noise, hence only driving straight/wind direction etc. I would definitely check the outside of the car, that includes underneath.
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

Point noted, mr. Rp0thejester!
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citroenguy
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by citroenguy »

When i worked at a Citroën dealer i heard about wind noise from the door frame sealing area on the C4 Cactus.
There was a service bulletin for this eventually.
So check with your local dealer if they can find the TSB
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by martin_b »

citroenguy wrote:
23 Jul 2022, 20:44
When i worked at a Citroën dealer i heard about wind noise from the door frame sealing area on the C4 Cactus.
There was a service bulletin for this eventually.
So check with your local dealer if they can find the TSB
Thanks for that information! I will definitely go to a dealer one of the next days.
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Re: C4 Cactus 1.6 BlueHDI 2014 whining noise

Post by GiveMeABreak »

Citroenguy is correct. The TSB is reference "a2aw012xq0", so they should be able to locate it under the "front door / diagnostics" section of the software system at the dealership.

The fault results from poor adhesion of the front door seals as shown below:
cactus wind trim.PNG
The solution is to place foam inserts as shown here:
cactus wind trim B.PNG
They subsequently did this on future builds. So obviously a poorly manufactured seal.