560 Rear Suspension - PeachParts Mercedes-Benz Forum

Hoopster · #1 07-16-2002, 07:18 PM

I have an 1988 560SEL w/175k on it, only owned for a short time. The Rear Suspension Sags, I have replaced, so far, both rear accumulators (Nitrogen Cells), rear leveling valve, new fluid and filter, but suspension is still not working. Rear shocks are dry and do not appear to be leaking, no leaks from suspension system (fluid level is constant). It apears that the system has not been working for some time as the rubber suspension stops are cracked. I do have a new set of rear coil springs, I have been wanting to tear the rear apart only once so I have not installed them yet, but my understanding is these will not fix problem more of a maintence correction. I have checked the sway bar links they dont apear to be broken. When I manually move the arm on the valve the system does nothing, when the bled valve is opened fluit squirts out so I asume pump is working. Is the problem Shocks? Pump? Sway bar Links? System needs Bled? Has system been damaged from long term neglect?

If problem lies in replacing rear shocks would used ones that have not leaked be ok? or should I pony up the $300 bucks per and get new ones?

What other rear suspension componets should be replaced (ie mounts, bushings,etc.) at this time?

It is also tire time, if I go to a 17" AMG 5 Hole replica wheel/tire combo can I expect any problems such as rubbing/clearance or will they be OK?

1991 560 SEC · #2 07-17-2002, 06:44 AM

It`s one of two things.

1 When the accumilators were changed the system needs to be primed. You do this by putting about 250 pounds or two friends in the trunk then start the car. You should feel it move up.

2 If that doesn`t work it`s your pump. You can bleed fluid because there is still some in the shocks and accumilators. With the car running, move the arm up or down. If the car doesn`t move it`s your pump.

John

mbdoc · #3 07-17-2002, 08:22 AM

Sounds like the leveling valve ins't allowing the fluid to the shocks. As this system IS self bleeding you don't have to do anything but run the engine to bleed the system.

Testing the fluid pressure at the valve is the best way to see if the pump is working. On the 1987/88 cars the inner-liner on the pressure hose can fail & plug up the system. There was a service bulletin on this subject.

autozen · #4 07-17-2002, 11:42 AM

A couple more thoughts. You can look into the reservoir while the car is idling and watch return flow from the pump that constantly circulates, because the pump always pumps while the engine is running. If you don't see flow, I'd remove the pump and split it to see if it's ok. If someone ran it low on oil,the pump is toast, because it needs the hydraulic oil for lubrication.If the pump looks fine, I'd change the shaft seal. They can suck air.Seals are available;the rest of the pump parts are not. It's a little irritating to be able to take a nicely machined pump apart easilly and not be able to buy a new shaft bushing.

Good luck,
Peter