91 560SEC Mercedes Rear Suspension EHA Valve FPR RennsportKC

Got the parts in for our little 560SEC project this week and I got as much done as I could in the time we had the car. We had a leaking EHA valve that was puddling fuel on the intake and causing an interior fuel smell in the cabin. We also had a fuel pressure regulator that was not holding vacuum, and between the EHA valve and this, the car would stumble when first started. Then there were the rear shocks that thunked over uneven rough surfaces such as railroad tracks.

The EHA valve off for replacement. The FPR sits right in the same area, and was replaced as well. This not only solved our fuel smell, but also fixed the stumbling when first starting the car!

Up in the air to tackle the rear suspension. The self leveling system (SLS) in these cars can be problematic in the rear. Usually the accumulators go bad and cause a thunking in the rear, but these were replaced before with no change. The struts rarely go bad, but they do have a ball joint at the bottom of the strut that will get play in it and cause the thunking, as well as rubber bushings at the top that can cause it. So I pulled everything out to inspect.

Top of the shocks is accessed through the rear seat.

A few holes allow access to the hydraulic fitting and the top mount nut.

Supporting the underside while dropping the shock.

And a shock out of the car. The ball joints were in good shape, and the shocks rarely go bad, so I decided to replace the rubber bushings and put everything back together. Since the shocks are over $400 each, I decided to put the old ones back in and focus our funds for now towards the unexpected fuel leak issue. These should have plenty of life left in them and they are easy to change out at a later date if need be.

Same findings on the other side. After it was back together, a test drive showed no hint of the rear end noise anymore, so I think we found the issue.

With the car up for an oil change, I noticed a lot of oil on the motor. The valve covers were leaking badly, so I decided to replace them.

With the valve covers done I changed the oil and cleaned everything up. With everything clean, I found the oil pan gasket was also leaking, lol. We will wait on that until the next oil change!

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January 24, 2015 at 3:29 PM

Do you have or know where I can get a shop manual book for a 91 560SEC ? Supposedly my nitrogen canasters on the rear leaked due to rust and the shocks overfilled with hydrolic fluid. I will eventually be working on the problem, am at first trying to run down info & torque specs, as well. – Thanks –

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