w126 560sel rear suspension problem

[rebel_mtc]

Hi guys my mechanic just replace the 2 accumulator air cells on the hydraulic suspension but the car would be bouncy at speeds of 120kph. like giving a free massage for the rear passenger ( the problem is intermitent)

Is there probably air trap within the lines? how do I bleed this out? The mechanic told me no bleeders for this system and it's self priming and air would go away after some time

[cool]

your mechanic is partially right, but you can bleed it thru your valve lever height adjuster, there is a small bolt which you can loosen and air trap will be released at that junction (do it while the engine is running and be careful to follow safety precautions. Also try to lower the height of your rear suspension, it will soften the hydraulic strut, and maybe give you a softer ride. Are you sure the aircell are ok ? (even thought their new).

[rebel_mtc]

Thanks for this info. I will ask the mechanic to look for this small bolt.

The mechanic actually made the height higher as he believes this would correct the problem but it seems he is wrong.

How do I check if the aircell is OK? it's brand new when we got it from the shop.

[rebel_mtc]

I loaded up the rear trunk with 200kg and run the car around for 10mins it seems to get the air out as I can see the hydraulic reservior level went down.

The ride became OK then the next day I had it's level adjusted since the height is high but to my surprise after the adjustment the ride become bouncy again any clues on what's wrong with my SLS?

[dpetryk]

Just because the level dropped when the car was loaded does not mean that air was removed. Under heavy load, the cells compress and the oil level drops. Did you try bleeding the system using the port on the leveling valve ?

[rebel_mtc]

dpetryk the mechanic did try to bleed it on the leveling valve but no more air was found.

My leveling valve is also brand new.

Any suggestions on how I can get the air out to prevent the bouncy ride?

[dpetryk]

I doubt that there is any air in the system. The service manual says that it is self bleeding. I think the problem might be a lack of restriction in the hose leading between the accumulators and the strut. If you think about it there should be some restriction there to provide dampening. No restrictions, no dampening, car bounces. I know some cars using hydraulic suspension use a "leaky check valve" (best description I can come up with) to provide similar reactions like a shock absorber does. Rolls Royce for sure. It makes more resistance in one direction over the other. I have seen special restrictors inserted into hoses to provide certain flow characteristics. I dont know if that is how MB does it but you might check the flexible lines attached to the accumulators.

I really dont know how the flow is controlled but it seems to me there must be some mechanism. The only part that has a chance of doing that is the flexible lines if it is not built into the accumulators or the struts which I dont believe it is.

Let us know what you find out when its cured.

[rebel_mtc]

so far my mechanic is at a lost. I also agree that the system is self bleeding but I don't know how to explain the bouncy ride with the new aircell and new leveling valve

[david s poole]

the system is set too high.this is probably because when the old air cells went bad the clamp that is on the rear sway bar is out of position.also check the fluid feed line from the reservoir to the pump.i have seen them get restricted and not allow full volume of fluid until higher rpm's which may account for the timing of when you say the rear bounces.

[Carlo(s)]

Just went through this a few weeks back. Here's what we did upon valuable advice from "cool" and others. Disconect rear lever and move lever to max height position; rev engine up to 1,500 rpm until suspension raises; then move lever all way down and put pressure down on the runk until suspension drops all the way; you can hear the air coming out of the lines; repeat procedure 2-3 times until air does not come out any more. Replace nut and tignhten up lever before driving away. Mine took 4 lever up-lever down tries until all air came out. Suspension leveled at right height and drove it in the freeway about 20 miles to get some good suspension bounces and it works like a charm now. My 2 cents worth; suspension should not be adjusted all the way up for normal driving as you mechanic suggested.

[rebel_mtc]

Originally Posted by Carlo(s)

Just went through this a few weeks back. Here's what we did upon valuable advice from "cool" and others. Disconect rear lever and move lever to max height position; rev engine up to 1,500 rpm until suspension raises; then move lever all way down and put pressure down on the runk until suspension drops all the way; you can hear the air coming out of the lines; repeat procedure 2-3 times until air does not come out any more. Replace nut and tignhten up lever before driving away. Mine took 4 lever up-lever down tries until all air came out. Suspension leveled at right height and drove it in the freeway about 20 miles to get some good suspension bounces and it works like a charm now. My 2 cents worth; suspension should not be adjusted all the way up for normal driving as you mechanic suggested.

I will give this a try tomorrow and hope it solves the problem

[rebel_mtc]

Here is the funny thing the car is bouncy when no passengers but with full of people the ride becomes better.....is this 560sel equip with some sort of sensor with regards to load then adjust the SLS accordingly?

One thing my mechanic did that I forgot to mentioned was he replaced the spring spacer with DOT1 or the thinnest from the DOT3 that he found installed. Does this have any effect on the bouncy ride?

I also notice during idling the hydro oil going back to the canister is not that strong can this be the problem? Is my oil line block??

I hope some one here can post a DIAGRAM of the 560sel SLS thanks.

I have replace new linkage, new leveling valve, new aircells. The hydro shocks is just 8 months old.

[rebel_mtc]

I read in one the threads about the accumulator and was wondering are this the shocks itself or is this the air cells?

How can I tell if my hydro shocks are damage? I did drive the car for 150km after a leak on one of the hydro shocks was found the car's rear end was really low all throughout my ride home since I can't find any hydro fluids along the way.

Does this hydro shocks have gas filled shocks on the inside? or are they just operated by the hydraulic fluids?

[rebel_mtc]

My SLS does go up and down if leveling valve is adjusted.