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So now you have done this, are there any fault codes or dash messages ?

Any other issues ?
 

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Discussion Starter · #82 · (Edited)
After a while, the pressure is down in some 150 bar and white warning and pressure issue is in DAS/STAR and warning appears on dashboard.

Also wondering, why the pressure fluctuates from 190 bar down to 170 bar in short - some 5 sec periods.

But also keep in mind that even, when I kept the revs at 900 rpm, and kept the pressure steadily up and flat some 15 mins in +170 bar; while I tested pressure sensor. the Diagnistic System says at the end that the pressure is lower than 15 bar and proposes to change the pressure sensor.

To me it sounds that the high pressure line is giving a low pressure indication; where that indication comes from? And at the same time the pressure sensor gives +170 all time...
 

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My next move would be to make up or buy some blanking plugs ....................

Start by capping the pipe feeding front VB, see if problem goes, if not try rear ......................

We are hoping by doing this that it gets you to a "ballpark area" ................

See if that isolates it to a specific area, if it proves the loss is on say rear circuit, you have now eliminated a whole heap of possible culprits, now move to blocking the feed to each rear strut ......................

Are you with me so far, by capping off components you may find say a faulty Strut, faulty Valve Block, etc etc (leaking off internally) ..........................

Other than that, I'm all outta ideas :(
 

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Diagnistic System says at the end that the pressure is lower than 15 bar and proposes to change the pressure sensor.

To me it sounds that the high pressure line is giving a low pressure indication; where that indication comes from? And at the same time the pressure sensor gives +170 all time...
This is confusing... @Dave2303, could you confirm what your DAS is saying with working system (next time you hassle eith ABC).
 

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Discussion Starter · #85 ·
Yeah, I understand what you say @Dave2302 ; closing the circuits - eliminating the area smaller to see, if the issue disappers.

@mersum1es - DAS says that change the pressure sensor. That has been done and the issue remains. What you mean refer to asking "what your DAS is saying with working system "?

Anyone know what should be the correct max pressure; 173 bar or 193 bar in this CL 600 year 2001?
 

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I reported the Working Pressure a way back, when I had the V12 CL in here last, I am very busy, sorry, so look back, see what figures I got, but IIRC it was around 193 Bar ........................

I do have that same Car coming in next week, for a B Service and some other work so if I get time I will spend time on SDS, can you post up a set of screen pics that you and or @mersum1es want me to look at please ;)

I can't promise, (lot of serious hassle in family and lot of work right now) but I will do my best to find the time for you ;)
 

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I mean when it clearly says 'pressure is lower than 15bar', is functioning system having same screen and accept values?
 

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I didn't look at that, I do believe that screen is only available after clicking the Fault Code and upcomes Guided Testing for that specific fault, my Customers CL doesn't have ABC issues so I doubt I can get to that screen ;)
 
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Discussion Starter · #89 · (Edited)
@Dave2302 :".. but IIRC it was around 193 Bar ......................."

You are right that 193 is very common pressure. But can you please tell me which year model you have there that 193 bar, please. I have measured a steady 193 from my friend's MB's, but those are a bit younger than mine. My MB is 2001 and it looks to attempt to keep and have a ceiling of 173 bar.

Is that a ceiling of 173 bar in 2001 year CL 600's?

Two of my Control units keep that limit as maximum - 173 bar. But the most recent, which I purchased from ABC specialists, goes up to 193, but returns to 173 immediately - with a new pressure relief block.

It sounds like the block is leaking automatically all above the 173 bar when I use this new pressure relief block. And when coming down to 173 bar, the pump starts to raise up the pressure again - and manages to go up to 193 bar in 5 seconds - and stops pushing....and the pressure leaks fast (in a couple of secs) down to 173 and the loop starts again.
 

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Customers CL is 2002.

From what you say above is it possible there are either 2 different pressure sensors, or perhaps a model year coding in the ABC Module that would affect this ?
 

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Discussion Starter · #91 ·
According to diagram, there is only one pressure measuring sensor and spring operated pressure relief valve. I am really wondering, where it gets "indication that the pressure is below 15 bar" during the pressure sensor test - keeping in mind that I am keeping 900 rpm all time and have 173 bar all during the measurement. The 173 bar can be seen both in analogical pressure gauge and in DAS/STAR MB Diagnostic software screen. And - at the end it says that "indicated pressure is below 15 bar" - what the holy cow???

How can it get 173 bar measured correctly, but where and how it gets "indication that pressure is below 15 bar"?
 

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At this point there are two possibilities:

1. The pressure reading is inaccurate.

2. The pressure reading is accurate.

If 1., then the sensor in the control unit needs to be replaced. I know you already did that.

Here鈥檚 an important question - does your analog external gauge read the same value when you get the low pressure warning? You said it matches in the video. What happens when you run the engine for 20 or 30 minutes and let the fluid warm up? I would rodeo the car to warm the fluid, create the low pressure reading, then verify the accuracy of the pressure sensor with your gauge. If it鈥檚 accurate, then you are moving on from 1.

If 2., then you have an internal leak. Pressure builds slowly in your system from the video. That surprised me. It should build more quickly, I would think. Good pressure initially, which slowly drops, makes sense as the fluid warms and becomes less viscous, and more able to get past the leaking point.

The pump itself could be on its way out. In 89+ posts, I didn鈥檛 see anything about the pump. A worn pump would behave exactly this way: good pressure with viscous fluid, but pressure falls off as the fluid warms. The slight bump in pressure with 750-900 RPM sounds a lot like a pump as well.

You could have a bad valve block. You said you replaced orings, but not the spacers? Again, so many posts, I鈥檓 a bit lost.

I don鈥檛 think your ride height sensors have anything to do with this. Stop looking there. The issue is fluid getting past a point that should be sealed up, like solenoid, pressure regulator, or pump internals.

I don鈥檛 see how the struts could leak: there is one pipe in. Fluid comes in from the valve block and goes out the same way. Unless there is an external leak, it鈥檚 not the struts.

Pump, pressure regulator, valve blocks. That鈥檚 it. Those are the parts that could allow fluid to flow past when it should stop. Those are the only parts that could cause low pressure, if the measured pressure is accurate.

Everything else, struts, lines, and accumulators, are a dead end, unless they are leaking fluid out onto the ground. Which hasn鈥檛 happened.

I am not a fan of the parts cannon, but if the pump has not been replaced, then, I would suggest trying it. I replaced mine at 95,000 miles after a hose blew and it ran dry. If they run dry, debris is created from internal wear and I chose to do the pump to prevent debris in the system.

I ordered a rebuilt pump from a company in Germany, and was not happy with the quality. That one was put in a box because I had it in my possession for several months before installation, so I didn鈥檛 feel that I could return it.

So, I got one from my local MB dealer. There was a core charge (original pump turned in for that) and installed it, along with new lines and then rodeo鈥檈d the car and changed the fluid and filter.

That鈥檚 where I am with your car - If the pressure reading is verified as accurate, then I would go with a genuine Mercedes pump. It was about $1,000. Then rodeo the car, exchanging fluid as you do, then put on a new filter and top off. Another $250 or so for 20 liters of fluid and a filter. Don鈥檛 know the prices in Finland.

Keep us posted. I鈥檓 still scratching my head on this one.
 
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Discussion Starter · #93 ·
"Here鈥檚 an important question - does your analog external gauge read the same value when you get the low pressure warning? "

Those two meters: analog and MB diagdosis do match at any figure: The analog meter shows the same figure as the pressure sensor on screen. Wjen I start the car the pressure starts from 0 bar; both instruments show the same all time when the pressure climbs to 173 bar. Also when the pressure comes down when running the car, the gauge shows the same figures. But the pressure is not really going down to 100 bar when the car is running.

I have already 3 new pumps and one old. All behave the same way - and all are from different companies. Even the original old pump.
 

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Discussion Starter · #94 ·
@Astro14 : " You could have a bad valve block. You said you replaced orings, but not the spacers? "

Good! That is good info! What are the spacers? I have replaced the O-rings three times and the "white Teflon rings which just support O-rings around the solenoids. There should not be any issues with those one. I have inspected all everytime very carefully using magnifier glasses and bright light. Are there something else called "spacers"?
 

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Should it go down to 100bar? Sluggish pressure rise and jumpy control could be air in system.
 

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Discussion Starter · #96 ·
@Astro14 : "That鈥檚 where I am with your car - If the pressure reading is verified as accurate, then I would go with a genuine Mercedes pump. It was about $1,000. Then rodeo the car, exchanging fluid as you do, then put on a new filter and top off. "

Well - the fourth pump seems to be the last but maybe it would be the correct card.

You did not suspect the suction restricter Y86/1 which is located in the pump. It is called also a throttle valve. The Control Unit should open it, if the pressure is going down, to give more fluid to the pump. That will happen for instance, if the car is lifted upwards and more oil is needed in the pressure piping system and in struts. That valve has been changed also three times - issue remains.
 

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Pump is inlet throttle controlled? Perhaps I go and open my SDS tonight, I really need to see hudraulic circuit and read system function (which I have bee chiming here long time...) I have fluid power education so I should understand those systems a little bit...
 

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Yes, spacers are the white Teflon rings, that鈥檚 what I meant.

I didn鈥檛 mention the suction valve because it鈥檚 part of the pump. I鈥檝e never even looked at it.

If it鈥檚 available separately, then, perhaps that is the next troubleshooting step?

edit: I see you鈥檝e changed it already. Hmmm...

And you鈥檝e replaced the fluid, exchanged all of it via rodeo, already?
 
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Discussion Starter · #99 · (Edited)
The ABC diagram can be seen here in colours. ABC System
The diagram does not show the throttle valve which is with the pumop. Nowadays it can be purchased separately, but the new one comes with the pump normally anyway. It is bolted to the pump and can be removed and replaced.
 

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Discussion Starter · #100 · (Edited)
@Astro14 : yes; I have changed the oil well totally and then every now and then partly adding there oil while changing components, when bleeding out air etc. The oil is very green and clean, Filter I have also changed so far twice. Its got now the 100 micron one, not the very tight one - 30 microns - not yet.

The pump inlet valve solenoid is controlled by the Control Unit. It opens the valve to let more oil to go to the pump, when the pressure goes down. I can check that's functionality - it is working, but if it is open all time, it would tell that the pump needs more oil all time; which would mean that there is internal leak somewhere. That checking I have not done.

Rodeo I have done several times, but with that the pressure will go down to 100 bar, where the Rodeo stops waiting the pressure to raise up to 120 bar, and then it starts to continue until the pressure is again at 100 bar. That period is quite short now - it takes appr. 10 - 15 sec only....so its not getting the Rodeo completed easily - will do it, but will take time. That Rodeo actually is quite strong method to the systems; and gets all the particles to move, as well. It should be avoided, but can be done, if you are in a hurry to get bleeding and air out in short time.

Is that right that the pressure in my car rises slowly compared to normal? As seen on video? here it raises up to 173 bar and stays there until some 15 mins and then gradually dropping down. If that time the throttle valve is getting electricity from the Control Unit all time, it would mean an internal leak perhaps. VID_20210421_112740.mp4
 
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