RANA 1
As an amateur, my approach may be a bit un-orthodox, but I think it works. Please point me out if I did something incorrect.
In general, removing and installing self-levelling shock absorbers are not difficult.
The main features of self-levelling shock absorbers are that they are part of the hydraulic system, and they have a line connecting to hydraulic suspension spheres. The tricky bit of removing them, I would say, is to remove the nuts on the lines. Mine were seized. Use flare nut wrenches with penetrating oil to do the job. In that way, the risk of rounding the nuts is minimised. In addition, prepare for oil spillage (400ml hydraulic fluid was lost when I did mine; total required for the system is about 2L. I did not drain hydraulic system for changing shock absorbers (I did when I changed hydraulic spheres), but do wear protective clothes and have eye protection on.
The 1st photo shows the new and the old absorbers, and the connection points highlighted in red circles. The 2nd photo shows the tricky connection point on the hydraulic lines.
My absorbers were bought from GSF costing about £350. MB dealer would charge a lot more. My car, which is a 1996 W210 E230 estate, was bought 5 years ago with a mileage of 137,000. I did not know when it was last time the previous owners changed them. But I changed mine 2.5 years later at 160,000 miles in April 2007 when they collapsed. Now my car's mileage is 192,000 and they are still in good working order.
The 3rd photo shows clearly about the product code. Hope this will give you a reference when you buy the parts.
In general, the steps are:
(1) Choke front wheels, begin from either rear side, lose rear wheel nuts.
(2) Jack your car up and place it securely on axle stand.
(3) Take the wheel nuts out and remove wheel.
(4) The first thing to remove old absorber is to slacken the nuts on the hydraulic lines. Again, use flare nut wrenches with lots of penetrating oil to do the job. Prepare for oil spillage.
(5) Remove the rest of nuts and bolts of the shock absorbers. For the top nut, the 4th photo indicates where about it is hiding in my estate. I am not sure where about for a saloon. I think boot is a good starting point to check.
(6) If you manage to remove the old absorber, installing new absorber is the reversing order. The 5th photo shows the new absorber installed.
(7) Remove and install shock absorber of the other side.
(8) Once new shock absorbers are installed, refill any hydraulic fluid lost. If you lose 400ml, for example, refill 400ml.
(9) Presuming your car is a saloon, make sure your boot is unloaded (keep spare wheel and basic Mercedes tools in), switch engine on and let the hydraulic system work for a while and stop the engine. Check for any fluid leakage from the absorbers. Not only the rear wheel arches of both side should have an equal clearance (not collapsed), the hydraulic fluid in the reservoir (in engine bay) should then be on the normal unloading level. Measure the rear wheel arch clearance (mine is about 3 inches clear). Check any shortfall of fluid from the maximum level mark of hydraulic fluid reservoir. I would suggest you fill hydraulic fluid in to the maximum level mark. If in case the fluid level is over the maximum level mark, I would suggest you use a straw and remove any excessive fluid. What you do with a straw is: put the straw in, cover and seal the top end with your finger, take the captured fluid out, release your finger and drain the fluid into a container.
(10) Now, load something heavy in your boot and perhaps let somebody sit in rear (when I did mine, I put my 2nd set of 4 wheels in). Turn the engine on and let the hydraulic system work under a loading situation. The hydraulic fluid in the reservoir should then be on a loading level – lower than the maximum level - but the wheel arch clearance should be the same (as measured under procedure (9)). If it is, then the job is done.
Hope the above and the photoo will help. Any question, please ask.
Sean
Hi Rupak
In general, the job is not difficult. When you look at your newly bought spheres, you should be able to figure out what is necessary to remove for replacement.
I have a Mercedes technical note for hydraulic sphere removal and installation in hand. Please let me know your email address so that I can send it (together with some photos) over to you for your reading.
The followings are my approach:
(a) Loose wheel nuts, jack your car up and support it with stands, rather than on ramp. Remove wheels. Wear protective goggles and protective clothes.
NB: Some information suggests to put car on ramp, go under it and release the hydraulic suspension height control lever with engine running. But this will cause the rear to be lower. I skipped this step for not only to avoid the risk of injury, but also to prevent me from breaking the lever and connected pipes as they were so rusty and looked fragile.
(b) Drain hydraulic fluid.
Clip and connect a clear plastic tube securely to the drain plug (similar to brake drain plug) located near the height control lever. Prepare for spillage by placing loads of cardboard paper on the driveway/garage floor. Lead the tube into a container for catching drained fluid. Loose the plug and drain old fluid out with engine running (better to have an assistance to start and stop engine whilst you are monitoring the flow). Once you see some foam coming out, stop the engine and let it drip. Close the drain plug when you see there is no more dripping and the reservoir should then be empty.
(c) Start with one side, slack the nuts connected to old sphere.
Use penetration oil and flare-nut wrench (11mm and 17mm), rather than line wrench that could round off the nuts at the hydraulic pipes. I rounded mine off ending up purchase of new mountings from a dealer. I am sure you do not want to repeat my mistake. Prepare for spillage in this step.
(d) Connect new sphere in.
This sounds easy but care must be exercised to ensure the pipes and the sphere are well connected. The angle of connecting the sphere and pipes, as well as the application of right torque, become crucial. Unfortunately I could not remember the correct torque. Perhaps somebody in this forum can point that out.
(e) Once done, repeat the same process for the other side.
(f) Measure the capacity of the drained fluid which should be about 1.5L to 1.8L.
(g) Replace the hydraulic fluid filter (under the cap of the reservoir) and start pouring new fluid into the reservoir. Pour 1L in first, and tighten the cap up.
(h) With an assistant turning on the engine, monitor the fluid flowing process again by loosening the drain plug until you see new fluid begin coming out (watch the fluid colour). Tighten the drain plug and stop the engine.
(i) Put wheels back on, lower car to floor and tighten wheel nuts.
(j) Top the reservoir with new fluid up to the maximum level. Turn engine on and let the hydraulic system run for a few minutes. Stop engine and top the reservoir up to the maximum level again if you see the fluid level drop. In total, I poured in 1.5L at this stage - at normal loading condition. Check for any spillage. Check and measure the height of the rear suspension (from wheel arch to ground) which should be the same.
(k) Load your car with heavy objects (I used a set of spare wheels plus). Start the engine for a few more minutes. Under this loading condition, with self-levelling suspension running properly, the height of the rear suspension should be as same as that under the normal loading condition. If it is, the job is basically done.
(l) Do a test drive under normal loading condition and check the level of hydraulic fluid level again.
(m) Check for any leakage and the level of hydraulic fluid frequently. Eventually I filled it up a couple of times. Totally I used about 1.8L.
Hope you find the above useful. Any question please ask.
Hope also any expert points out any mistakes I have made or advise for any room of improvement.
Regards
Sean Ng