C Class 'clonking' noise from rear nearside

[Alex Argent]

Hi Guys and Gal
Over the past few months, I have been plagued by quite a loud 'clonking' (thin metallic) noise from the rear nearside when driving over rough surfaces/speed ramps etc. It doesn't do this every time - about 1 in 5 times and also appears sometimes when steering hard left (even at low speeds).
It definitely sounds like the exhaust knocking, however it's been into ATS and National and they have both said they cannot find anything wrong - the exhaust hangers and rubbers are fine.
I have a sneaking suspicion it may be something to do with the suspension, but a couple of cursory glances and tugs underneath the car reveal nothing untoward.
I am aware that the control arm bushes on 202's have a tendency to wear fairly frequently, but haven't a clue if this would give rise to the clonking noise. Can anyone throw a bit more light on this problem or suffered from similar symptoms? If not I suppose it's off to the stealership to investigate (at £85 p.h. I think that even Dire Straits would be cheaper to carry out a private investigation! )
Look forward to some replies,
Alex
Edit in red

 

[jan]

Hi Guys and Gal
Over the past few months, I have been plagued by quite a loud 'clonking' (thin metallic) noise from the rear nearside when driving over rough surfaces/speed ramps etc. It doesn't do this every time - about 1 in 5 times and also appears sometimes when steering hard right (even at low speeds).
It definitely sounds like the exhaust knocking, however it's been into ATS and National and they have both said they cannot find anything wrong - the exhaust hangers and rubbers are fine.
I have a sneaking suspicion it may be something to do with the suspension, but a couple of cursory glances and tugs underneath the car reveal nothing untoward.
I am aware that the control arm bushes on 202's have a tendency to wear fairly frequently, but haven't a clue if this would give rise to the clonking noise. Can anyone throw a bit more light on this problem or suffered from similar symptoms? If not I suppose it's off to the stealership to investigate (at £85 p.h. I think that even Dire Straits would be cheaper to carry out a private investigation! )
Look forward to some replies,
Alex

How strange...I had very similar symptoms with my C class...
When I had the rear tyres replaced the problem disappeared so never did find out what was causing it.

Sorry I can't offer any help.

Jan

 

[PJH]

We had a (thin metallic) noise on Wifey's C180. Turned out to be the warning triangle. Only 2 of the feet had rubbers on them, hence it was loose in the boot lid.

 

[Alex Argent]

Jan - Tyres recently rotated due to new AMG wheels being fitted. Noise was apparent before this was done.

PJH - Good thinking . Unfortunately, I'd already tried this, in fact I took everything out of the boot - including the spare wheel - when I was applying a process of elimination. The noise persists

Keep 'em coming guys, I'm running out of ideas (apart from the suspension fault).

Cheers

Alex

 

[C240Sport97]

I had a metallic clanging sound from under the car for 2.5 years -- finally pissed me off so much I got someone to look at it. I have a C240 Sport like yours.

The sound was coming from just behind the automatic gearbox. There's a horizontal (across the width of the car) brace just behind the gearbox that holds another bracket inside it (this other bracket is hidden from view until you remove the brace). It was this bracket that was loose.

 

[Birdman]

Is it still clonking?
I had a similar-sounding problem, with an occasional rear end clonk under the conditions you describe. Tried all the same remedies too. A theory the garage put forward was the boot counterbalance lever mechanism thingy - I'm pretty sure that's what was implied. Mind you, mine's a W210 but maybe that's not relevant because they never found out what it was and it just went away for no apparent reason (who says German cars don't have character?). It may of course return with the warm weather.

 

[andy_k]

try the rear anti roll bar drag links - they are a favourite for making hard to trace noises as it's usually an end bush that collapses so you can't immediately see it. It took me 3 months to find out that what was wrong with my W124 even though I'd supposedly checked them

HTH

Andy

 

[Birdman]

Didn't know the W210 had a rear anti-roll bar. Let alone a drag link. I'll speak to the (independent) garage.

 

[Alex Argent]

Wow - this is an old thread!

I should have posted the diagnosis and repair beforehand.

Eventually took the car into MB Bury St Edmunds, and they found the rear left spring had corroded and a small piece broken off the bottom end where it sits in a kind of circular tray. They also informed me it's quite a common problem (I've heard that statement tooooo many times from the stealership ). Apparently, water collects in the tray supporting the spring.

One new spring and £90 odd later, the noise went away for ever - well at least until the next time!

 

[Robbo]

Yes its a common problem, I had a rear spring go last year. Wish it only cost £90 to repair though. Your dealer must have quite low labour rates as the spring itself cost me £50. Either that or I was ripped off by my dealer.

 

[Alex Argent]

£28 for the spring, half an hour labour, plus VAT! At least that's what is on the invoice .

 

[Robbo]

I need to find another dealer!

 

[Birdman]

Eventually took the car into MB Bury St Edmunds, and they found the rear left spring had corroded and a small piece broken off the bottom end where it sits in a kind of circular tray. They also informed me it's quite a common problem (I've heard that statement tooooo many times from the stealership ). Apparently, water collects in the tray supporting the spring.

Had exactly the same problem at the front. Mine went off like a pistol shot so didn't take too long to discover what it was.
You may have gathered I use M-B Bury too, having given up on M-B Norwich (always scrounging for more work ) and M-B Ipswich (far too expensive ).

 

[Dieselman]

To check anti-roll bar links grip the car at the roof and rock it from side to side. If the links are faulty they will knock.

 

[genesis1210]

got the same noise from my clk320 - most annoying clunk from rear offside - good news is its going to be sorted under warranty - if they find it!!