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Old 11-18-2000, 12:40 AM
Registered User
Join Date: Oct 2000
Location: Oakland, CA USA
Posts: 221
Hi, recently my '87 560SEL has become rather bouncy in the back. Basically any dip in the road sends the rear end into the air, some of my taller friends are even bumping their heads when they sit in the back seat. What was the question...oh yeah, does anybody know roughly what this type of repair might cost? I assume it's suspension...Also, if I cannot have this fixed right away, am I doing any damage driving it this way?
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Old 11-18-2000, 07:43 AM
Registered User
Join Date: Jul 2000
Location: Toronto, CANADA
Posts: 1,193
What's your mileage? Also have you tried the hand push test? With your car parked, go around the back and push down really hard with your hands on each corner of the rear. If the car bounces up and down several times before stopping you probably need new rear shocks. I'm pretty sure these Mercedes shocks are supposed to last around 150,000 miles or more, so if your mileage is around here that's what you could be looking at. I don't know prices, but if that is all it is, I can't imagine you are looking at more than $100 or so per side plus labor. Check the parts shop for prices. I think your model has self-leveling anf beefed up rear suspension compared to other w126 models. There may be other problems which could get expensive, but it may just be the shocks. Have it looked at. I don't think driving with the car like that will damage the car, but it will seriously affect your handling, and you may get into an accident you could otherwise have avoided. It's definitely worth doing.

JP Toronot

Jason Priest
1986 420SEL
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Old 11-18-2000, 08:32 AM
Beatle Juice
Posts: n/a
When you push down on the rear of your car and it feels stiff, the accumalators for the self leveling system have problably gone bad. Maybe $100-$150 each and not to hard to replace. Be careful not to crossthread the lines.
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Old 11-18-2000, 09:36 AM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Definitely ACCUMULATORS. Possibly aggravated by beat upper strut mounts.

On any hydraulic suspension systems accumulators are the actual springs. They are steel spheres about 4-5in. in diameter. Inside is a diaphragm with high pressure Nitrogen gas (say 1000psi - it varies in different systems and I don't remember the exact spec for this case)holding the diaphragm against the wall.

As system pressure builds, at 1000psi the fluid starts compressing the gas and the diaphragm leaves the wall. At say 2000psi the fluid now has compressed the Nitrogen to half the container with the hydraulic fluid pressing on the diaphragm in the middle of the sphere and the car is now being lifted.

If at this moment a bump is hit and the suspension compressed, the strut squeezes the fluid into the accumulator against the gas pressure and the pressure raises to say 3000psi. Now the pressure rebounds and expands the strut in recoil. This action is in effect a gas spring taking advantage of the compressibility of a gas.

Once the gas is gone, the whole system is a non-compressible fluid AND it is non-compressible. Driving in this state tears the poop out of every thing.

If you can visualize the conditions that I portrayed with a fully charged chamber and then one totally dead, then you need to visualize the states in between. As the system looses its gas differing amounts of strut movement cause bottoming out.

I recommend replacing these chambers at mile intervals because their relative state can't be determined except with either great experience or expensive testing. We have done our shop wagons at 60-90k intervals.

Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
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Old 11-18-2000, 03:41 PM
Registered User
Join Date: Jun 2000
Location: Tucson, Arizona, USA
Posts: 180
I just bought a 560SEC, and the first owner drove it even though the hydro pump is broken. I'm pretty sure the rear struts are pounded--does anyone know how much they cost? I hear >$400/piece?

Also, would the pump breaking have launched particles into the lines and trashed the rest of the system too? Seems like it will be a great ride when this is fixed. Thanks, Andrew Seidel.

89 190E 2.6
86 560SEC
83 300TD Turbo
75 240D
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Old 11-18-2000, 03:45 PM
Registered User
Join Date: Oct 2000
Location: Oakland, CA USA
Posts: 221
Thanks for all the advice. I gave the back a little push this morning, and it bounced a bit, the car has 160k miles, so I guess it's about time. I'll take it in this week. Thanks again!
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