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  #1  
Old 04-20-2004, 10:38 PM
fhmajid
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Self Leveling System Question

Hi,

Anyone know if the basic pressure in the 124 self-leveling system should be 30-36 Bar? Also, while the system is filling, should the system pressure be a minimum of 130 Bar?

These are the values quoted by the MB CD. My dealer performed the pressure test this avo, and came back with a prognosis of all is okay, yet reported a 1 bar basic pressure.

Something does not add up...

Thanks
farrukh

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  #2  
Old 04-21-2004, 11:48 AM
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Location: South Eastern, MA
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The entire system doesn't pressurize to the levels you've quoted. If you remove the top off the reservoir you can continue to operate the car and the height will maintain itself so long as fluid remains in the system. The pressures you're quoting are most likely for the nitrogen spheres which absorb a portion of the bumps from the rear shocks.
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Old 04-21-2004, 01:49 PM
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According to my book the value 130bar is the minimum pump output at idle. The control range is 133 to 153 bar and these are not the pressures that the actual struts see. That is the pressure that sits behind the value ready to add to the system pressure. If the car was overloaded the system would have the ability to receive 153bar pressure to lift it.

The accumulator show a new pressure of 23bar and a usable min pressure of 15 bar. The only pressure test I have ever been concerned with was this value. To read this value one must discharge the system and hook into just the accumulator (the other side must be blocked off and the pump is started. Because it has this high pressure capacity it instantly brings the pressure to the gas pressure. Once at the gas pressure the gas compresses and the pressure increase goes from instantaneous to a slow filling as the gas is compressed and the internal diaphram is moved and the chamber becomes partially full of hydraulic fluid.

The pressure continues to rise as fluid is pumped in until the pressure is great enough to lift the load to the required height. I would guess this pressure is way less than the 130bar, when lightly loaded and only gets into the controlled end of pressure when loaded to the limits.

If you asked for a pressure test the only one of value would be the accumulator status pressure. If they start at 23 and are no good at 15 and you can feel them at 0-5bar, one can see that a decent test is to find out the accumulators are deffiecient before they are hydrolocked and are driving the ridged struts through the fenders.

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