After loading the 560SEL down at Costco last night, it seemed to me
that the left side of the car was lower than the right. With the
self levelling system, I thought that this shouldn't happen.
I have looked over all previous posts that I could find about the
system, but could find nothing that diagnoses the accumulator air cells.
Can a bad one cause my problem? I'm going to check the shocks and cells
this weekend. What should I look for besides leaks?
Thanks for any and all tips regarding this system.

__________________
VR
1967 250SL

Vaughn,
Hopefully someone more knowledgeble than me will respond, but I have been looking at 560 SELs to buy for the last 6 months. A friend of mine who owns one had to replace the nitrogen spheres as soon as he purchased the car, and I understand they wear out fairly commonly. I also understand they're fairly easy and relatively easy to replace.

I am looking very seriously at a '91 560 SEL with a rather harsh ride, so I suspect the spheres are bad in this car.

After driving with bad accumulators the system often fails to lift anymore. This usually solves itself after the accumulators are replaced.

The idea behind the accumulators goes like this: The rear struts are given the job of supporting some of the load in co-operation with the springs. As load is applied the valve allows the pressure to rise the whatever is necessary to maintain level ride. At this point if the struts were full hydraulic and the car hit a bump the pressure would rise but have no where to go and the strut would act as a rigid membe. The accumulator is originally filled with high pressure Nitrogen pushing a diaphram against the wall of the sphere. As fuid pressure is built the diaphram is compressed till maybe half the sphere is nitrogen and half hydraulic fluid. The pressure of the Nitrogen has doupled and the total pressure now lifts the car. When a bump is hit the shock now can push the fluid into the remaining area of the sphere which compresses the nitrogen to very high pressure which then recoils like a spring.

Over time the Nitrogen is lost through the diaphram and the system becomes "water logged". Then the strut acts as a rigid member.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I hope you can follow this instruction I made...This is for a 1987 190E-16V..I believe they are similar in design..

HOW TO CHANGE 190E 2.3-16 SELF-LEVELING SUSPENSION CELLS OR ACCUMULATORS.

1. Jack up the Left rear side of the car, make sure the handbrake is engaged. Put block in front and back of one of the wheels to prevent the car from rolling. Also put a jack stand under the car for safety.

2. Put old newspaper under a wide opening container below the cells/ accumulators to catch dripping hydraulic fluids.

3. Loosen the smaller nut at the side of the cell first and let the fluid drain for a couple of minutes then remove the nut. At this point the system is without pressure, loosen and remove the larger nut at the end of the cell. Do not loose the 2 washers, otherwise you will have a leak later. Remove the 4 mounting bolts and remove the cell. Watch out for leftover fluids in the cell. Installation is reverse.

4. Follow same procedure with the right side. It is actually easier because of more room to work with.

5. Remove the jack stand and lower the car.

6. This is how to drain the reservoir. (Others might have a better idea) Get a syringe or aspirator with a flexible tubing at the end and suction the fluid from the reservoir. Then replace the fluid in the reservoir with fresh hydraulic fluid ¾ full. (Make sure to use the recommended type.) At this point start the car and open the trunk, sit on the lid and bounce the rear of the car, occasionally checking on the reservoir level. Take the car on a test drive and enjoy your new suspension. Check the fluid level and the cells for leaks. That’s it, I hope this help.
Regards,

Orlie

Orlie, how did the repair work out? What were your symptoms
before the replacement or was it just time to do it?
Thanks.

__________________
VR
1967 250SL

Replacing the rear shocks is something to check as well, esp. around 100k miles. Mine rode like a truck until they were replaced. Not cheap from a dealer, a few hundred dollars.
Check out the "parts shop" here and I'm sure you'll find better prices.

Cheers,

The rear 'air cells' are simple to replace if that is needed. The symptom is not having any/enough rear suspension travel.

There is not anything to cause /prevent uneven side to side level except sway bar. The rear shocks are manifolded together and get the same pressure.

Hi,

I forgot to mention, before I replaced my accumulators, I replaced the rear shocks with OEM parts. The left side was leaking oil so I replaced it. A year later the car was bouncing so bad that I almost hit the ceiling when I hit a bump. Someone from this forum told me about the accumulators.

After they were replaced the car rides and handles better. I got the accumulators and the fluid from parts shop.

Regarding the hydro-pneumatic suspension, and specifically the shocks, I have heard consistently over the years that they should only be replecd if they are observed to be leaking. Is anyone aware of a failure mode for these shocks other than leaking which could cause poor performance? I should replace the N2 cells in my 300TE 4m but they aren't high enough on my list of to-do's yet. Besides, the car still rides well at 205k miles.

Hi Mike,

I had mine replaced on the 560 SEL a few months ago at 100K miles. The car rode like a truck -- nearly teeth jarring if you sat in the back.
The hydro-pneumatic suspension was bled and deemed to be in good working order as well. I never suspected anything was up with that, as the car "sat" well etc. It was all in the shocks, pricey at that. Get them from here if you can.

My 89 was not leveling and they replaced the actuator valve I believe. It now sits right and levels. I also lost that harsh thunking noise when going over speed bumps. Don't know the price as it was warranty work, I believe the part was like $400.

560SEC ridding a bit harsh lately, 68k. I had the rear actuator done about 8 months ago. It was working but would not keep the height up after shutting her off. The ride was sweet, little harsher than my buds 420 but nice. Highway is mint, most roads are mint but I am starting to hear more than feel every bigger bump including those damn road reflectors. Is this the spheres or something else? Where should i check for leaks. I also need to lower the rear suspension a tad but it has been that way since before I did actuator. About 2 months ago I added some fluid to my resevoir and since then it has gradually gotten harsher. Did not overfill, it did take a qt. I have been keeping an eye on it and level is good. Closest I can think is they never topped it off after they did the actuator. Any ideas and let me know what to look for. Thanks, Nick