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Discussion Starter #1 (Edited)
I originally had a problem with clunking at the rear of my car when going over bumps. Mechanic diagnosed it to be self leveling linkage/valve, that got changed and the clunking went.

The ride was still feeling a little rough (very slight clunking when going fast over humps), so sent it back to mechanic. Seems like the valve is broken again and only driven like 20 miles since it was replaced. He said it might be due to a fault strut, hes looking into it. Any idea if it could be strut (hope not), or it was just very very unlucky that it broke again?

Thanks
 

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I would guess it more likely that the accumulators are bad and not providing a cushion effect so the fluid pressure peaks are too high.
 

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Discussion Starter #3
I changed the accumulators about 300 miles ago so I'm not sure wherever that is the problem? However it was done by a local mechanic, maybe he didn't installed it properly (although I felt smoother ride so im guessing it was done properly).
 

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Clunking could be control arm or strut bushings or the mounts on top of the rear struts. I don't think I've ever seen a report of a failed levelling valve. I had my linkage arm degrade and become disconnected. I think others have experienced this, too.

Repairing the Self-Leveling in a W140 Mercedes


That does not cause clunking, however. It simply stops the valve from levelling the rear. I don't see how any issue with the valve could cause a clunking problem.

Brett
 

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Discussion Starter #5
Maybe Im just being picky with the clunking, its rarely there but the whole car felt just a little stiff so I got it checked out anyway. Could the valve be causing a stiff ride and not absorbing road humps as well as it should? Mechanic said it seems valve has broken/damaged (he changed the valve or linkage 20 miles back) and will look into it and see if the struts have gone and causing the valve to break.

What could be causing the valve to break?
 

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The valve itself can't cause a rough ride or noise. If the valve is not working you would notice that the car is not level. If the car looks level than most likely the valve is working.
 

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You have to crawl under, disconnect the linkage, and operate the valve manually to see if the valve is working properly. Or, I guess you could put a large amount of weight in the trunk (maybe just have a couple people sit in the trunk) and see if the rear rises to level like it should. If it does, the valve and linkage are fine.

Also, there is the sway bar mounts and bushings for possible clunk sources.

Brett
 

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valve wont cause noise.

and i guarantee you it was never bad to begin with. "mechanics" heh
 

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I have to agree that there is no way a bad leveling valve body would cause a "clunk" noise. Bad sway bar links can cause the problem. A bad lower control arm outer bushing can cause the problem and a bad bump stop on top of the strut (ram) can cause the problem.

I'd suggest getting in touch with an indy shop that actually knows their way around a W140.

Jayare
 

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As others have recommended, bushes are the most likely scenario. On the w124 which has a similar set up with the SLS, clunking at the rear is often due to sub frame bushes being worn out, but a good look around with the car on a ramp it should be easy to spot if any bushes need replacing.
 

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As others have recommended, bushes are the most likely scenario. On the w124 which has a similar set up with the SLS, clunking at the rear is often due to sub frame bushes being worn out, but a good look around with the car on a ramp it should be easy to spot if any bushes need replacing.
ok lets end this subframe bushes in a 140 fallacy before it begins yet again. Nothing in common with the w124 problem where you commonly have to drop the rear subframe to correct it! 140 does not have said issue.
 

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Discussion Starter #12
I've decided to move the update thread back to here.

As the self leveling valve was broken, I got it replaced. But mechanic (apparently has experience with w140) says it will keep breaking due to faults with the struts.

The way he explained it to me (might explain it wrong) is that when the ride drops down it dosent trigger the self leveling, so the oil gets pushed back towards valve and front of the car? Therefore breaking the valve, and he's saying the problem is the struts, and unless we replace the struts the valve will keep breaking.

The other problem I get the rear end mainly doesn't seem to be absorbing the little holes and impurities in the road. Going fairly slow over speed humps seems nice and smooth but cant cope with the small holes in the road at all.

I don't see what the problem could be, the accumulators was changed although not by a w140 specialist so maybe it was installed wrong? Could struts could be causing it? I've got mid range tyres but ride should be that bad I guess?
 

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Discussion Starter #13
Brett: If you disconnect the linkage and manually operate the valve with the car running, does the rear of the car raise and lower properly?


I've left it up to the mechanic to sort all the linkage/valve out so I don't know how to do that, but what would that tell me?

nhzruthless818:are your shocks leaking hydraulic fluid? how is the top mount of the shock doing? what exactly do you mean when you say clunky?

I dont think the struts are leaking, although because the valve broke the fluid leaked out somewhere through the front end of the car I think. By clunky I mean car dosent seem to absorb the little holes in the road very well causing rough suspension. I'll ask mechanic about the mount, but he's done a check over on the car including mounts and he thinks the cars in good nick.
 

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You need to find a mechanic, not some scammer. This guy is so full of shit. You are being taken for a long, expensive bumpy ride by this asshole. The hydraulic system is a recirculating system. Fluid is ALWAYS being sent back to the pump on the engine. The valve breaking and sending fluid to the front is pure bullshit. Please excuse the language, but you are being cheated. If there is a leak at the front, investigate it! There are several hoses which may be leaking or the pump is failing. The rear struts have nothing to do with the valve breaking. When the accumulators were installed, they have to be blead of air through a simple process of manually raising and lowering the back end by moving the valve. Once that is done the valve linkage should be adjusted--sounds like none of this was done. If there is still air in the sytem then you will have a bad clunky ride. Sounds like the dealer may even be less expensive than this excursion.
 

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Brett: If you disconnect the linkage and manually operate the valve with the car running, does the rear of the car raise and lower properly?


I've left it up to the mechanic to sort all the linkage/valve out so I don't know how to do that, but what would that tell me?
You have a mechanic telling you that the valve is broken. Manually operating the valve and observing if the rear suspension goes up and down as it should will tell you if the valve is working. If you can't do this yourself, you cannot tell if the mechanic is telling you the truth. I agree with Chuck. Time for a new mechanic, if you can't DIY.

Brett
 

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Discussion Starter #16
Ah thanks for the reply guys!
Well there was 2 mechanics, first one was a w140 noob and he changed the accumulators and steering pump (was no need!). This is for clunking I used to get.

I then had enough and went to this Mercedes specialist place, the guy seems pretty honest and experienced. He said he used to work on them while they were on production and worked on quite a few. He changed the linkage or valve and that sorted the clunking. But hes failed so far to sort out the rough suspension, and valve keeps breaking.

Looks like I have to find a new mechanic or just take it to the dealership! From what you guys said It seems like there might be air in the system caused by the first mechanic, maybe the second mechanic just assumed that the accumulators were installed fine but there actually not? Therefore ruling it out and saying its the struts fault?
 

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It's just really hard to tell exactly what you mean about clunking and rough suspension over the internet. The car really needs to be driven by someone (or someone needs to ride along with you) to know what you're talking about. I don't recall reading a single report of levelling valve failure since I've been reading this forum. All I can say is if you believe your mechanic, then change the valve again. If not, find another mechanic if you can't or won't do any work yourself. You have multiple opinions here that suggest the valve unlikely broken, but we haven't seen or touched your car.

The dealership is just another mechanic. It's not like it's a completely different animal.

Brett
 

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Discussion Starter #18
Thanks for that Brett, I do believe in my mechanic and don't think hes a type of person to rip me off (unlike last mechanic). Say there was air in the system from badly installed spheres, how would one go about taking that air out?
 

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how about your damper valves? one on each side or acceleration sensors .If I was you I would visit MB dealer just to perform short test that will cost you $35 that way you can see whats wrong with it.
 

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how about your damper valves? one on each side or acceleration sensors .If I was you I would visit MB dealer just to perform short test that will cost you $35 that way you can see whats wrong with it.
Deltz has not indicated that his car has ADS. The adjusting damper valves and acceleration sensors are ADS parts.

Brett
 
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