Knocking noise from rear of C5 2.2 HDI mk 1

[kca]

My C5 2.2HDI SX has a strange knocking noise from the rear end on random occasions. I have owned the car from new it is a 2001 51 reg and it has 91000 miles on it.
The noise has been there for a few months, braking, turning or the road surface does not seem to effect it. Sometimes I hear it on a smooth flat road without turning or braking and occasionally on speed bumps. On other occasions I can drive 20 miles or more and not hear it at all.

It sounds like something metal sticking and then releasing and on occasions can be heard when bouncing the cars rear suspension when stopped. I have had the car on ramps and everything looks fine, I also had it checked at a local garage and they found nothing. It was MOT tested 3 weeks ago and passed with no problems, but the noise is still there and seems to be happening a bit more recently.

I have removed everything from the boot and checked the spare wheel is secure. Could it be the rear spheres as I know I had to change spheres on a BX I had a long time ago, but the ride became very firm and bouncy on it. The rear suspension on the C5 seems less firm at the rear compared to the front.

Hope someone can help as the car still looks and drives like new.

[Hell Razor5543]

It is likely to be the rear arm bearings. They do age, and can make strange noises as they do. It is possible to do them yourself, but I got mine done for around £400 (including parts and labour).

[GiveMeABreak]

Also there was a known issue of a knocking noise from the rear - I had it on my C5. Citroen simply applied a soundproofing fix, consisting of pads and other material and glued it down. If I recall it was on the rear axle. They also put a load of deadening material under the rear bench seat and glued that down.

[Hell Razor5543]

Simple question. Has it always made this noise, is has it only recently started?

[kca]

Thanks for your help, it only started a few months ago. I did suspect the arm bearings but though they would have lasted longer than the mileage it has done, or do they wear with age.
Also if the bearings failed completely would it be dangerous. I have been thinking of getting another car so did not want to spend a lot of money on it.

[Hell Razor5543]

As you have had the car since new, and you know what work it has had done to it, I would say it is probably worth the cost of getting the rear arm bearings done (assuming that this is what the problem is). Yes, it may seem expensive, but that should be another 15 years (or 100,000 miles) before you have to worry about them again. Let us say that it cost you £600 to get them done (it should not be that expensive, more like £450). That would work out at £40 per year. I cannot say if it would be dangerous if they failed.

[kca]

Thanks again for your help, I will get someone to give me a price to have them done. Although it is difficult to find some one to do any work on the suspension here in Scotland.

Thanks Again.

[Hell Razor5543]

This list might help. They are garages that most people would recommend . Please read them carefully, as there may be one or two that are there to WARN members away from;

https://www.frenchcarforum.co.uk/forum/ ... m.php?f=15

If you manage to find a garage who can do it, get hold of some Plus Gas (NOT WD40) and spray it on the union between the calliper and the brake pipe (ideally every day for a week or so beforehand). Over time this may have seized, and will make things difficult. Plus Gas is very good at releasing these, so using it daily on a join that is going to be released in a week or so will have a beneficial effect.

[kca]

Cant thank you enough, will do as you say if I decide to keep the car.