Hydraulic Problem on W126 560SEL 1989 - PeachParts Mercedes-Benz Forum

zcc · #1 03-18-2006, 09:34 AM

I have a question about hydraulic on 560SEL 1989, I posted before about that problem but now the problem raised.

My 560SEL 1989 has a four wheel hydraulic system and an adjustment arm near the light switch. My problem is that when I leave the car for only one minute or more the car goes down; so I have to switch on the car for 5 minutes to take the normal level. What is the most likely causing the problem?

I have no hydraulic oil leakage and I use the original MB oil. The car is Euro specs.

Thank you : ))..

stevebfl · #2 03-18-2006, 01:51 PM

How is the ride when charged up? Since you drop so fast I worry that your reservoirs of pressure are dead. Without a reservoir of pressure any leak immediately takes the car down.

Try putting the lever to the lock position and see how fast it goes down. Without external leaks you have two possibilities. The first is the height valves. Putting the system in the lock position will prevent leaking level valves from leaking the system down. The second mechanism is leaks past the shock piston. This leak is captured and there is a spec for the acceptable volume, but it is real hard to test. This manner of leak is not stopped by the lock position.

I would check this first but the results are not exact as the mastervalve itself can leak internally back to the reservoir.

All of these leaks are internal and will not lose fluid. Unless your accumulators (pressure reservoirs) are new they need replacing. If there are leaks they are undoubtably due to running on dead accumulators. Running on dead accumulators feels like riding a buckboard; harsh, bouncy. Try bouncing each corner.

zcc · #3 03-18-2006, 02:46 PM

Thank you so much Mr. stevebfl.

When I put the lever to the lock position the car needs arround 2 days to go down.

The accumulators seems to be fine and smooth because no harshing or bouncing while driving.It happened to me once before days while the car was working but not driving I noticed that the accumulators red light on the dashboard was blinking then let red, when I pressed the pedal it let off but after seconds it let red again so I had to press the pedal again but never happened. I guess that the pump is weak but not sure.

Please Mr. stevebfl ask me more information to isolate the problem. Here mose of the ppl repeal that system and replace it with a normal one and I don't want to do that. Thanks : ))..

stevebfl · #4 03-18-2006, 02:59 PM

If it takes that much longer when locked then you do have a valve problem. Since the car goes down so quick I would probably locate the return lines from the two height valves (at the master valve) and remove them and catch the back flow. One should be distinctly larger than the other. If it doesn't seem to be, try leaving the master height control valve in the low position and block the individual return lines one at a time. (The master valve is blocking both when it makes the leak take longer) The car should last more than two days so you need to also isolate the system pressure check valve and should probably replace the system accumulator (there are five accumulators, one for each strut and a systems one). The fact that your light came off and on tells me you aren't working with a large reserve of pressure.

zcc · #5 03-18-2006, 03:31 PM

Now I understand the word accumulator; that one looks like the ball. I ment to say that the shock-absorbers (struts) are fine.

But sometimes if the accumulators changed the car will never ever comes up and then I need to remove the whole system and install a normal one.

So shall I go with replacing the five accumulators? I'm really afraid of making the system useless after I replace them

But if I'm running with a dead accumulators why the car is so smooth while driving? I mean no buckboards or so.
I'm really sorry to bother you about this problem but no one solve it for me in Kuwait. Thanks again : ))..

zcc · #6 03-19-2006, 05:17 AM

Or shall I replace only the four accumulators?

zcc · #7 03-20-2006, 03:49 AM

Can someone instruct me with what to do first please? : ))..

zcc · #8 03-21-2006, 08:20 AM

Please guide me Mr. stevebfl.

zcc · #9 03-23-2006, 03:27 AM

zcc · #10 03-25-2006, 05:49 AM

Now it comes worse. Everyday I have to wait 5 minutes before it comes up again, guys please help me what shall I do. No one here understands that system.

zcc · #11 03-28-2006, 06:08 AM

zcc · #12 04-03-2006, 10:46 AM

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