1982 W126 Suspension Problem


New Member
Jul 26, 2011
Chevy Tahoe 2001
I just bought a 1982 500SEL. The car comes with the hydraulic suspension, and it is damaged, so the car is laying on the differential housing as well as on the engine lower armor

My question is if I can change to a coil spring option so the car can be used, or at least moved, while I can fix the hydraulic system

Many Thanks


MB Club Veteran
Aug 19, 2002
Not always
Firstly , we need to confirm whether you have all round hydropneumatic suspension which works on all four wheels , or just self levelling suspension which is only at the rear ?

The easiest way for you to tell is to see if there is a knob on the dash which can be pulled out to raise the ride height , or lock it for transportation , neither of my cars have this option , but it would be below the instrument cluster . If you have the pull knob , then you have all round hydropneumatic suspension .

The rear-only SLS system just works automatically as on the estate cars .

In each case the suspension still uses coil springs to take most of the weight of the car but has hydraulic rams in place of the shock absorbers - there is a hydraulic pump in the engine bay which pressurises the system and the ride height is controlled by valves connected to the anti roll bars - if the car drops , the valve opens and allows mineral oil to be pumped into the strut and this lifts the car up until it achieves the correct level , if a load is removed and the car sits up too high , the valve allows oil to flow back from the strut into the central reservoir until the car drops to the correct level - in line between the valve and the ram , there is an oleo-gas sphere with pressurised nitrogen gas on one side of a diaphragm and the mineral oil on the other : because gas can be compressed while oil effectively cannot , the gas allows some 'spring' in the suspension and also performs the function of the shock absorber .

Both systems are essentially the same in operation , but the four wheel system is much more complex with multiple valves and more pipework .

If your car has dropped right down , I would suspect a broken coil spring . Here , in the UK , I paid just under £100 each for two new springs for my 500SEL about two years ago - this was from Mercedes : I would not go anywhere else for these as Mercedes operate a 'points' system for spring rate according to what equipment your car has ( this can be determined by your dealer from the chassis number ) and will give the correct spring for your particular car out of a range of several available - they are colour coded by 'dots' painted on the springs for different stiffnesses . Aftermarket suppliers do not usually have more than one spring for a particular model .

The most common fault with these systems is that the hydraulic pipes under the car rot and the fluid leaks out ; the diaphragms in the spheres also tend to burst , allowing the nitrogen gas to escape into the system and this causes the ride to become very firm . Valves can sieze and pumps can fail but this is less common . Rams seldom fail . The major parts ( rams , valves , pumps ) are very expensive , but the spheres and pipes are not too bad - the main cost involved in replacing these is labour . The ZHM mineral oil is also about £10 a litre ( at least was the last time I bought it for my estate cars ) .

Hope this is of help .

While you could certainly remove the system and fit standard springs and shocks , I feel it would be a pity to do this . I am looking around for the parts to retrofit rear only self levelling to my car for use when towing with it , so far have a pair of rams , but looking for a donor car to get the rest from .

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