C5 2.0 HDI woes

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Hi guys, I've been reading this forum for a while now, slowly building up my frenchy knowledge. I bought the aforementioned C5 2.0 HDI 110 back in March, and since I bought it it's had this horrible grumbly vibration like noise. I'm not really sure it is a noise, it's lessened significantly with a window down, and can't be heard from the outside. This leads me to believe it's something oscillating off the body, reverberating throughout. It occurs below 1,500 RPM in any gear, and gets louder with more load. Under no load it's silent, but when accelerating or decelerating it's present. Since it happens when decelerating also I assume it's after the gearbox in the drive line? I've heard of the injector dribbling issues but they can't make noise when off throttle. It sounds exactly like the motor is labouring, but it's not. Could I be looking at inner CVs or the O/S driveshaft bearing? We have a Xsara Pic 2.0 HDI 90 as a taxi in the house with close to 250k miles also which I've compared to mine, and it is silent in comparison.

I've replaced the alternator bearing and aux belt, which needed doing but made no difference to this. The clutch needed to be replaced so I threw a Valeo solid flywheel in while I was at it. The noise got louder after this, it was only in the background before. It's been getting progressively louder since. The car has 120k miles on the clock. Is this a common problem others have found? I have a hunch it might be the lower torque mount, so I have a polyurethane mount on the way to me to see if it helps. It's getting to the point where I have to drive a gear lower than normal, or I can't hear the radio or hold a conversation, which is taking a hit on the MPG-o-meter. There's absolutely no noise present above 1,500 RPM, or in neutral/clutched in. Any help is mucho appreciated, I'm stumped

[Peter.N.]

If you can feel vibration it could be the top engine mount/stabiliser. Both of mine have some vibration below 1500 rpm compared to the 2.1 XUD in the XM but its bearable. Sounds as though yours has the same problem but its being transmitted to the body. Try disconnecting the stabiliser link and running it. What did you drive before?

Peter

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Bugger, I suspected engine mounts so I went away and bought the bottom one! Will the engine not be hopping about in its frame with the link disconnected? Now that you mention it, I did read something on another site about harmonic frequencies transmitting through the top mount on a petrol Xantia at a certain frequency. Could it be that this frequency shifts to 1,500 on the diesels, and is transmitted by a failing mount?

I had a mk1 Focus TDDi before the C5 and a mk4 1.3 Mini before that. Both had no problems idling around town and picking up when requested with no grumbles.
I also have a 1.2 16v Seicento for autotesting, but that's quite a bit vibratey due to solid engine mounts

[Peter.N.]

If you drive it very gently it will be OK with the stabiliser disconnected just to try it as it it does transfer some vibration to the body. I was rather disappointed with the Hdi engine for that reason, my XMs would pull from tickover with virtually no vibration thus eliminating a lot of gear changing. I think either the flywheel is to light on the Hdi or the body isn't sufficiently stiff.

Peter

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That would explain why the solid flywheel made the vibration worse, it's a good 5 kg lighter than the DMF. I will try this out tomorrow, if this solves it I'll be a happy Citroen owner once more Thanks for your help Peter

[Peter.N.]

That's interesting, I did ask someone if their car was better with the solid flywheel but got no reply - I know now!

Peter

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Just to clarify, I don't think there are any vibrations from the flywheel itself, although there is a bit of clutch judder in stop start traffic. It's definitely better than a failing DMF anyway!

I had a look at that stabiliser this morning, I didn't realise there was a mounting under it, hence my reluctance to remove it, leaving just the gearbox mount and the torque mount behind! The old one does look pretty buggered to be fair, the small end has the bushing in the middle sitting at an odd angle. There's also scrapyard markings on the underside, so I guess the previous owner replaced it before. I took it for a quick spin and the resonance is definitely lessened, but is now present throughout the rev range. I presume this is because the engine steady is missing though. I'm not 100% sure it's causing it, but I've ordered a new one for the princely sum of €20. Between this and the poly torque mount, hopefully any vibrations are damped out.

[Peter.N.]

Let us know how you get on.

Peter

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4 weeks later and I got around to fitting the top torque mount! My first impressions were good, the car is a lot quieter inside and out at idle, however the main vibration is still there. The poly bottom torque mount I ordered has arrived, so when there's another gap in the weather (possibly another 4 weeks?!?!) I'll fit that and see what happens.

[taffy]

can u post a pic of that polly bush?
sounds nice!

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I sure can taffy. As you can see it's in two halves with an alloy tube in the centre, so it can be installed without needing to be pressed home. That's what stopped me getting an OE mount, I don't want the hassle of removing the driveshaft, changing the diff seal, refilling the gearbag with oil, and still having to bring the mount to a garage with a press. Powerflex have this red one specifically for diesel engines to cut out typical diesel vibrations, compared to the usual yellow compound. The issue I have is that it's not officially supported on a C5, this is for a 306. I'm kind of assuming it's going to fit The outer diameter is the same so it should be ok...hopefully?!

[taffy]

i think it should fit..they should do pollys all over!!
looks nice mate cheers for the pic
how much was it out ofinterest?

[taffy]

haha it will be tight as a ducks ass after fitting that!

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It was just under £30, still cheaper than the OE equivalent and it has a lifetime warranty! I'm hoping that even if the old mount isn't the source of the vibration, this will at least stop it transmitting to the body.

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All fitted this morning, and it has definitely tightened things up! There's no more start up or shut down judder, and it's also cured what I thought was clutch judder. The downside is the vibrations throughout the body at idle are immense. The front right wheel is visibly shaking! I'll live with it for a few weeks and see if the mount beds in any bit, otherwise it'll have to be an OE rubber mount going back in. But for now, it's an improvement.