1999 e320 rear hydraulic suspension - Mercedes-Benz Forum
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post #1 of 10 Old 02-08-2016, 11:23 PM Thread Starter
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1999 e320 rear hydraulic suspension

My suspension went flat on my 99 e320 wagon 4-matic.
Good news is that there is absolutely no fluid leak.
The fluid just dropped about 1.5" in the reservoir.
From what I understand it must be an accumulator that went bust.
The power steering still works perfect.

My questions:
1) Before I take off both accumulators, is there an easy way to check which of the two accumulators went bad ?
2) I dont understand why a bad accumulator will make the suspension go flat.
Should it not still rise, but not do much shock absorbing ?
3) Anything else but the accumulators that could cause this.

Thanks
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post #2 of 10 Old 02-09-2016, 04:25 AM
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1.5"? Looks like both accumulators have gone. To check them you have to remove them and insert a screwdriver into the open end, if the driver goes all the way in then the unit is kaput.

They have a diaphram inside and behind this it is gas filled. Once the diaphram breaks fluid can fill the whole unit hence the 1.5" drop in fluid.

ERIC

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post #3 of 10 Old 02-09-2016, 08:25 AM Thread Starter
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Thank you very nuch Eric.
Clear and easy solution.
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post #4 of 10 Old 02-09-2016, 08:30 AM
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Let me know how you get on with this please.

ERIC
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post #5 of 10 Old 08-06-2018, 05:13 PM Thread Starter
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Hi Eric,
I know its been a year+ since I posted this, but just have another question to know what to expect if I have the same problem in the future.
I will post some photos to the thread as you requested.

1) You seemed amazed that 1.5" inch would be for only one accumulator, technically what do you expect the drop in reservoir will be if one accumulator goes bad ?

2) How do they test at inspection that these cars have a bust accumulator at the back. When it originally went, the car went through inspection and they did not pick it up. Unless I drive with it I cannot see any indication it is bust doing the standard hoppity test pressing gown seeing if it comes back once.

Do you have a procedure for me to test the rear suspension before I take to inspection as I dont want to have a fail and not understand it. How do they detect it, I cant unless I drive it, which they dont. When I drive it I can feel it is dead.

3) Once the accumulators are replaced, does it lift the car slightly higher off the ground, or does it stay the same and the air in the reservoirs just control suspension shocks, but the level stays the same.

4) Also, I know you can set the height it must lift up, but I see absolutely no mark or indicator systems on the piston, where I can see if it lifted up or not.
I expected something like a pin that should align with another pin on the chassis, but see nothing. They can be adjusted and apparently you can see in some way what the initial height was before startup and the final height after startup. I just dont see any such indication.

There is very little online info available on the suspension of these models.

Thanks

Last edited by daimlerbenzuser; 08-06-2018 at 05:27 PM.
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post #6 of 10 Old 08-07-2018, 06:27 AM
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Originally Posted by daimlerbenzuser View Post
Hi Eric,
I know its been a year+ since I posted this, but just have another question to know what to expect if I have the same problem in the future.
I will post some photos to the thread as you requested.

1) You seemed amazed that 1.5" inch would be for only one accumulator, technically what do you expect the drop in reservoir will be if one accumulator goes bad ?

2) How do they test at inspection that these cars have a bust accumulator at the back. When it originally went, the car went through inspection and they did not pick it up. Unless I drive with it I cannot see any indication it is bust doing the standard hoppity test pressing gown seeing if it comes back once.

Do you have a procedure for me to test the rear suspension before I take to inspection as I dont want to have a fail and not understand it. How do they detect it, I cant unless I drive it, which they dont. When I drive it I can feel it is dead.

3) Once the accumulators are replaced, does it lift the car slightly higher off the ground, or does it stay the same and the air in the reservoirs just control suspension shocks, but the level stays the same.

4) Also, I know you can set the height it must lift up, but I see absolutely no mark or indicator systems on the piston, where I can see if it lifted up or not.
I expected something like a pin that should align with another pin on the chassis, but see nothing. They can be adjusted and apparently you can see in some way what the initial height was before startup and the final height after startup. I just dont see any such indication.

There is very little online info available on the suspension of these models.

Thanks
You will find a world of information and answers in this link;

https://www.benzworld.org/forums/w21...-steering.html

https://www.benzworld.org/forums/w21...hocks-buy.html
https://www.benzworld.org/forums/w21...mlulators.html
https://www.benzworld.org/forums/w21...000-wagon.html
https://www.benzworld.org/forums/w21...ar-shocks.html
https://www.benzworld.org/forums/w21...ling-rear.html

https://www.benzworld.org/forums/w21...ue-values.html
https://www.benzworld.org/forums/w21...hydraulic.html

ERIC
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post #7 of 10 Old 08-07-2018, 12:51 PM Thread Starter
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Oh well, I read all that years ago and although that site has a lot of data, it is not really helpful. I sort of got better answers here on this site.

Anyway I took off the left accumulator and it is seemingly shot. A dowel pushed into the opening went straight to the back. I will check the other one in a while.
I dont know how tough these diaphragms are supposed to be, or how easily they are pierced. The dowel was blunt though and I felt no resistance or Nitrogen gushing out if it was pierced.

How can they quote me $2500 to do an easy job like this.? Its easier than changing a darn battery ?
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post #8 of 10 Old 08-07-2018, 05:56 PM Thread Starter
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Accumulator Photos

Two photos.
First One with the dowel in all the way.
Second shows deep the dowel went in.

As you can see the dowel went in about 90%.
I am not sure if this is normal. The diaphragm would not have any space to work with unless it works by vacuum which is not the case.

So where is the diaphragm located 1/4 way 1/2-way or all the way ?
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Last edited by daimlerbenzuser; 08-07-2018 at 05:59 PM.
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post #9 of 10 Old 08-07-2018, 10:21 PM Thread Starter
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I figured it out myself. The diaphragm should be about 1" from the opening so these are thoroughly shot.

This problem was pretty sneaky on this car. I initially noticed the drop in fluid, which made me believe something was wrong. Driving it didnt give much away so I was never sure if anything actually was wrong.
Only now that I checked the accumulators do I see that there is a problem.
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Last edited by daimlerbenzuser; 08-08-2018 at 09:12 AM.
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post #10 of 10 Old 10-18-2018, 10:11 AM Thread Starter
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General comment based on experience.
If you dont want this to happen to your self leveling system, make sure that the dealer first show you what fluid they are going to put in your self leveling system before they proceed and ask for the empty canisters back. In my case the dealer put the wrong fluid in probably knowing that the car will fail after a couple of years etc etc. When I checked the codes of the cans they used it was not the same as what was prescribed for my MB and the prognosis by MB was that the system will fail in a few years. This info I got from Germany. I realized the error about a week later and apparently that is already too late. I was told the accumulators will fail and so also the levelling valve. I immediately went to a local shop and had them completely flush out the self-levelling fluid and put in what I supplied which was the correct codes. So that error from them cost me quite a bit of money and they just shrugged it off when challenged, saying that the different number fluid should work. So as expected the change was too late and the self-levelling failed after about 4 years and the valve failed two months after the accumulators were replaced just as the HO in Germany told me would happen.

So I never go back there again. If you can DIY, a MB will last you a million miles with minimum expense. Since
I decided to DIY, I have no more trouble period.

Last edited by daimlerbenzuser; 10-18-2018 at 10:52 AM.
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