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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Hold on, FEBI? Last I checked, the only ABC fluid recommended was Pentosin CHF 11S.
 
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CL600 year 2001
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Looks to be so that FEBI is working perfectly , as well in ABC - at least in my friends same type of Mercedes. And one should remember also that on year 2001 the oils were not so developed, as they are today.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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What exactly is your febi fluid brand that you're using? I'm thinking the spec sheet for Febi is different than chf11s.
 
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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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I wouldn't know, the spec sheets are the same in this case.

Spec sheet looks to be fairly similar, especially at the 100C temp.

Also, febi 21647 is the same as 81256, according to the spec sheet as 81256.

You could have a problem with the power steering cooler in front of the car.
 

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CL600 year 2001
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Thanks Deplore! The temperature is according to the STAR OK - it has never been over 85 Celsius, and the problems start well below that temperature, already.
 

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W220 Moderator
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I still think it is a valve leaking by, just maybe a strut, but that shouldn't make pressure go low as there is no return per se, the struts only have one line from the VB ...................
 
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2005 S600
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The pumps make good pressure when the fluid is cold. When the fluid is hot, the system pressure drops. I'm going to rule out the fluid for the moment since the OP says it's relatively fresh.

It has to be either: bad pump (frustrating, but not impossible) or a leak internal to the system that is bleeding off pressure constantly.

Since the pressure regulator has been ruled out, my money is on a valve block leak.

So, let me ask this: does the suspension drop when parked?

Have the valve blocks been overhauled or replaced in your ownership?
 
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CL600 year 2001
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Hi the valve blocks have new O-rings, does not drop when parked.
But I need to check/change those again also in rear - as I already did to the front; no change.
 

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Also, there is that relief valve, you say you put the old one back, the old one could have been the fault all along, makes sense to me ;)

Without studying the drawings again, (as I haven't had one in for a while), it is possible there could be other valves as well as the level valves ?????????????????????

What about the actual Pressure Sensor ? Could that be reporting wrong pressures, but not out of range enough to throw a fault ?????????????????????

@welwynnick is the expert on these, he has done more with them than me, he might have time to drop by ;)

HTH,
 

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CL600 year 2001
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Discussion Starter #33
Yes, it is possible that the old pressure valve is not operating properly. I just wanted to test it while waiting the new one with black sensor to come.

Now it is good time to refurbish the control unit to make sure that there is not any issues with components/solderings.
 

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Agreed, well worth carefully studying it for a dry solder joint.

Not trying to tell ya how to suck eggs btw, but I use 10x Magnification and find that even joints that look good by eye can be cracked on many PCB's, (think K40 Relay Module found on CLK, SLK etc) ;)

HTH,
 

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CL600 year 2001
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Thanks Dave - I will use a Finnish specialist for that; they did the same successfully already the ignition coil control box to my car and have experienced for these. Vekatronics Oy - Etusivu
I already agreed with them; they said that they have done it before and for other control boxes they do every day - have experience.
 

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Yes, it is a job I've only recently started doing out of necessity due to my location and the "one off" nature of my SLK V8 Project. Also needs decent equipment too, I set up a whole bench dedicated to it in my office area ;)
 

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CL600 year 2001
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Discussion Starter #37
Just got the ABC Control Unit back from soldering and installed it back.

Yes! The problem was in bad solders. Now the pressure stays steady 173 bar all the time when testing Pressure Sensor with the STAR DAS! Earlier it was gradually going down, dropping, when running the 15 min test. Now it is 173 all the time!

Alk the issues are not solved yet, however, but this was the main issue, I assume. I changed the pump even twice - because the STAR was showing remarkable drop in pressure during the first 15 mins.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Interesting. This is the first I hear about it.

Do you know where the cold solder were? On the SMD or the pins?
 
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I just talked briefly with the guy who did the work; he said that the board was covered with silicon(?) which took a bit time to clean off first - and then he went through all the solder points. he mentioned that some of those were weak ones.

He also said about the two processors, that he did not see any reason to change those and did only the cleaning, soldering and covered all again with silicon (?). He said that it will now last more than this 20 years it already had lasted.

But really I have measured the pressure sensor testing many times and always it went down within that 15 mins - and once it even dropped - like collapsed - from 150 bar suddenly to 129 bars, but climbed up to 140 in two minutes; and then continued gradually reducing the value finally to level of something like 120. This was when I was doing only the pressure sensor testing, which lasts some 15 mins. And now it was amazing - just straight line steady from the start to end in 15 mins; 173 bar, not more, not less. I was expecting 190 bar.
 

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CL600 year 2001
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Problems continue...I don't understand...

Does anyone know how to test the STRUTS' internal leak with DAS ? I think I saw that one somewhere on its screen - but I am not sure is it even possible to do?

Looks to be so that the pressure control limits the pressure to 173. Maybe that is enough, but what happens after a while is an ISSUE:

If I elevate the car and actuate the level control, the pressure drops. If I run DYNAMIC TEST with DAS (3.000 RPM while DAS is raising and lowering the car automatically - I assume it is less than RODEO; and the car will not do it) , the pressure drops even down to 10 bar!

The locking solenoids work perfectly - the car stays overnight steady up - I have not tested longer time, cause it has been so interesting to test it; but I believe those solenoids are OK. The issue is somewhere in operation solenoids or in struts now.
 
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