C5 2.2 hdi 136 strange buzzing sound

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ml11ML
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Joined: 07 Oct 2020, 10:22

C5 2.2 hdi 136 strange buzzing sound

Post by ml11ML »

Hello,

I've recently bought a C5 break exclusive with the 136hp 2.2 hdi. It has been mostly fine besides all the spheres going hard a week after I got it (just enough time to get me used to the soft ride and then take it away) and some other minor issues like the auto wipers going crazy but this is making me slightly worried as I haven't heard anything like this in any other diesel but I have never been in another car with a HDI so I don't know if this is just a normal thing for these engines.

The strange sound happens only between around 1700 rpm to maybe slightly below 2000 and only when the engine is under a medium to high load. The car runs and drives fine besides being gutless below 1500 rpm compared to other cars but I assume this is normal and just because this turbo can't make boost at low rpm.

I don't (yet?) have a lexia to check any details but there are no codes or check engine light that I can find with a generic OBD scanner.

I have recorded 2 videos on seperate days in 6th gear that do pick up the sound but it is louder in real life. If anyone has any idea about what this is and how bad it is that would be great.

video 1:
video 2 with no rain:

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GiveMeABreak
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Re: C5 2.2 hdi 136 strange buzzing sound

Post by GiveMeABreak »

Can't really determine anything wrong from those videos to be honest.

As for your spheres, they wouldn't all suddenly go hard - they would go harder over time. Secondly, SPORT suspension mode can keep the car in a firmer setting for longer when active, so you are effectively riding on 4 spheres instead of 6.

ml11ML
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Joined: 07 Oct 2020, 10:22

Re: C5 2.2 hdi 136 strange buzzing sound

Post by ml11ML »

Oh, okay.

Must just be a normal thing for this engine then. But it is really unexpected when you drive gently for a while and then step on it only to suddenly hear a loud buzz especially when no other car has ever done this.

As for the spheres they didn't all go bad exactly at the same time. First the front center sphere died which made the car suddenly feel very stiff in the front (the corners could still be pressed down) and the next day the rear center sphere went too. Shortly after replacing the center spheres the front sides started becoming harder and harder to the point where it is now very hard to press it down on the front corners. Even with my entire body weight over the wheel it barely moves at all and the ride is getting stiffer slowly. Rears still seem okay for now as i can get it to bottom out when parked if i sit in the trunk but the ride has also slowly been getting stiffer in the rear just much less than in the front. Sport mode does remove much of the body roll in the corners when turned on but when driving straight I don't notice it doing anything differently which as I understand should be correct that it only changes the suspension when turning.

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GiveMeABreak
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Re: C5 2.2 hdi 136 strange buzzing sound

Post by GiveMeABreak »

Did you actually bleed the system after changing the spheres?

Flat ground, remove LDS cap, suspension on lowest setting with engine running, then make 10 SLOW turns, lock to lock (without holding the wheel at either lock).
Then return steering wheel to dead ahead, switch engine off and check LDS fluid (see below).
If there is any 'fizzing' or bubbles, allow these to dissipate and repeat andther 5 turns of the wheel lock to lock.
C5 MK I LDS A.PNG
C5 MK I LDS A.PNG (41.6 KiB) Viewed 48 times
C5 MK I LDS B.PNG
C5 MK I LDS B.PNG (29.91 KiB) Viewed 48 times
" a" : LDS fluid minimum level.
If the level is below the " a" mark, add 1 litre of LDS fluid.
MAXI mark on the LDS fluid reservoir.
LDS fluid maximum level:
Hydractive suspension 3: Reference BASE
Hydractive suspension 3+: Reference HYD

ml11ML
Posts: 4
Joined: 07 Oct 2020, 10:22

Re: C5 2.2 hdi 136 strange buzzing sound

Post by ml11ML »

After changing the spheres I set the suspension to highest and lowest about 5 times until the fluid level stopped getting lower (obviously added more so it isn't low on fluid) and also turned the steering lock to lock twice which did nothing to the fluid level. Will try this correct procedure tomorrow and report back if anything changes or not.

ml11ML
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Joined: 07 Oct 2020, 10:22

Re: C5 2.2 hdi 136 strange buzzing sound

Post by ml11ML »

There weren't any bubbles at all and the fluid did not drop any more. The side spheres really must be going bad. I will replace them anyway as I already have some new "comfort" ifhs spheres and I'm now just waiting for the sphere removal tool because taking them off without it is really annoying.