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CL600 year 2001
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14 Posts
Discussion Starter #1
Hi, I purchased the MB with issues in its ABC.

My question:

Does the ABC pressure, which can be seen with STAR/DAS, be affected, if the solenoids which are controlling the height have poor O-rings? Should I replace the O-rings to get struts working properly, or is my issue only and still and again only related to poor pump efficiency?

WHAT IS DONE AND NOTED:

STAR (i have it) showed that the pressure at B4/5 sensor is 174 bar. The car cannot raise front when warm and gives warning (about low pressure).

I purchased a Polish 250 eur refurbished hydraulic tandem pump - but it was producing the same. Low pressure - 173 bar.

I purchased another one with 650 eur refurbished pump. That is also producing 174 bar.

STAR says that there can be an issue in pressure: need to check pressure sensor B4/5. That is working properly - I tested it with STAR.

When warm, the car cannot raise up front corners. When cold it can raise and lower all corners.

I was wondering if the possible internal leaking in solenoids keeps the pressure low. Or do I just need to get another pump again - the third refurbished?

Or does that B4/5 give wrong figures?

Ari, Finland
 

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W220 Moderator
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Please update your user CP info....

click on your icon----> click on Account Settings---->
go to Account Details----> add vehicle details---->
ADD your make and model YEAR ---->
Add your Territorial Location ---->
click save

What does a Pressure Gauge tell you ?

What about Pressure Relief Valve ? ............. BTW I've never had to look in depth at this so have no idea where Relief Valve actually is, but there will be one ;)
 

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2006 S600
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259 Posts
I've bought several Polish refurbished tandem pumps, and they're fine.

I don't think it's your pump, you would otherwise see different pressures, not the same.

It points towards the pressure control valve which is behind the right hand side front wheel.

Nick
 

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Thanks Nick,

I knew it had one, just couldn't remember exactly where it was ;)
 

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2005 S600
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682 Posts
I believe that your pump(s) are good. That's a decent pressure at 174 BAR (2500 PSI, roughly). But, the pressure downstream is not being held, so, it may be the pressure regulator (valve on SDS) that has the pressure sensor and a small accumulator on it, located on the right side of the engine bay, towards the firewall. It may also be that the control valves do have blown o-rings and can't hold pressure to the line that they're trying to pressurize. There's a lot of weight on each strut, so you need a lot of pressure to raise it up. You may have 174 bar line pressure from the pump, but a small internal leak and that pressure bypasses the strut it's trying to raise, and you get this failure.

Don't buy another pump, I don't think that's your issue. I think I would start by pulling the valve blocks and rebuilding them. Some good guides on this forum, including o-ring sizes needed. You'll want to rodeo the car when you're done. IF it rodeos properly, you're all set. Use that rodeo to exchange the fluid - return line to a bucket, fresh fluid in the reservoir, and you'll need at least 10L.

The fluid is more viscous when cold, so whatever leak/failure you've got is masked by thicker fluid. When it warms up and thins out, it leaks past the bad o-rings, or regulator valve, or whatever.
 

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CL600 year 2001
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14 Posts
Discussion Starter #6
The pressure regulator and gauge B4/5 and its entire block and the black nitrogen filled damper under the right side passenger - those I purchased and installed during the overhaul this year. They are MB parts from ABCspecialist in Netherlands. Also the pressure pipe from pump to that valve is new - including the damper.

I can do rodeo, when the oil temperature is below some 40 Celcius. But when the oil temperature exceeds 60 Celsius, the pressure goes down to 100 Bar in rodeo and it stops movements. The pressure raises up to 120 bar in some 20 seconds - the rodeo starts and again in 6 seconds the pressure goes down to 100 Celcius and rodeo stops.

It behaves like the oil is getting too liquid - like water - and it looses its viscocity.
 

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2007 E220CDI, 1990 300E-24V, 1987 W124 3.6 AMG build 1993 E500 W124, 94 320CE, 1997 W140 S280
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The pressure regulator and gauge B4/5 and its entire block and the black nitrogen filled damper under the right side passenger - those I purchased and installed during the overhaul this year. They are MB parts from ABCspecialist in Netherlands. Also the pressure pipe from pump to that valve is new - including the damper.
Was this low pressure fault there before you replaced these components?

(Just because they are new doesn't guarantee they arent defective)
 

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2005 S600
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682 Posts
While viscosity loss with temperature is normal, you’re clearly losing pressure as a result of a viscosity drop.

Off the wall question; have you ever changed out the ABC fluid? That is, run the car, while doing a rodeo and drained the return line while adding fresh fluid to the reservoir?

There may be multiple factors at work. Tired fluid with lower than normal viscosity, for example, along with leaking o rings...which yield these symptoms.
 
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CL600 year 2001
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Discussion Starter #9
When I got the car its left-front corner was down. I changed all the O-rings in solenoids, changed the oils and filters.

I did not drive the car after that episode, so I do not have a good, reliable reference. I only did rodeo and tested it briefly in my garage. I already had decided to change the pump.

I am not desperate, yet. ;)

I am ready to test and do anything: it cannot be impossible to fix!

I ordered another set of different oil trade mark - FEBI - and will test with that next. Now I have documented all pressure and temperature variations and would like to see, if the oil trade mark will make any difference.

It will at least make a good flush.

After that I shall change the O-rings again in front, if the issue is not solved.

My son is getting his driving license within next two weeks, do that is my target for the MB.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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When I got the car its left-front corner was down.
That's bad strut, internal plunger valve in the strut has gone bad, not the valve block.

When you start the car, does it rise up and stay level?

174 bar is decent for pump, but a reman or new pump should be easily outputting 200 bar and maintain at least 160-170 bar through rodeo. If you're dropping pressure during rodeo, that's a bad or weak pressure relief valve. I keep forgetting if this pressure relief valve is on the pump or on the little valve right next to the pressure accumulator.
 

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CL600 year 2001
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31 Posts
When cold - it works perfectly; it raises fast and lowers fast - all works as new. The locking valves work also without any problems all the time - I can leave it for 2 months and it is still standing there.

The issue comes gradually when the oil is getting above +40 Celcius. At +60 Celcius it is not working well at all and finally cannot create the pressure enough to lift the heavy front. That will happen, when the oil temperature is some +80 Celcius.

It is not a strut, because all the struts will gradually stop working caused by the low pressure.
 

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CL600 year 2001
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The pressure regulator and its pressure sensor B4/5 are located on the right hand side, under the car behind the engine bay. That is new, as well as the whole assembly.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Then perhaps you're on the right track, change all the fluid and go from there.
 
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I am not familiar with ABC, what ABC function says about fluid temperature? Is it a temperature limit (safety) which prevents system working? What is 'normal' working temperature of the system)

It sounds like you do have a leak, which is increasing when oil temp rises (Gap may grow when system in hotter, warm fluid is thinner --> leaks more --> bigger leak is heating fluid even more. Heat camera could show which part of the system is heating most rapidly <-- leak is there.
 

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CL600 year 2001
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31 Posts
Problem obviously solved! Got that message form the ABC pressure valve and sensor supplier - where I ordered the new set in January.

Good afternoon,

Thanks for contacting us. Yes, you ordered the wrong part, but we can help you further. 2 models valves were installed in your model of car according to Mercedes Benz. A2203200558 is currently installed in your car. You ordered and received A2203200858. The price is equal. Please send back the wrong unit, and we will send you the 0558 model free of charge.

Please note there were 2 different models pressure relief valves installed for your model car.

A2203200558 with black sensor A0125429217, also numbered A2203270131
A2203200858 with grey sensor A0035422018, also numbered A2203270231
(same price)

The valves are different, one should use the correct valve as is currently installed, although the same electric connector fits.
Checking VIN number and Mercedes system for the right valve won’t work, as it always point to the A2203200858 (latest model).

Please check with your mechanic which model is used in your car, and which sensor you actually would need.

Mvgr, Thanks, Vielen Dank,

Your ABCspecialist support team
 

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Well, thank heavens for that :) I'm really glad you've got it sorted, these kind of oddball issues can turn into an absolute nightmare to find, I've known guys end up selling their Cars for lesser issues ;)

Thank you for posting the outcome :)
 
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CL600 year 2001
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I tested with the old one - not better success! Must be something else, as well. The funny thing is that all these three pumps show exactly 174 bar at start, when the oil is cold; +20 Celcius. They also behave the same way in rodeo; they go down to 100 bar very fast - in 2 minutes, and then rodeo stops, until the pressure raises up to 120 bar - and then it comes in 6 seconds back to 100 bar and stops. It contiues that cycle.

That cannot be a coincidence.

The next one I'll do is to send the ABC control unit to be checked and re-soldered.
 

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Any chance you are using the wrong fluid with too low viscosity at temperature ? I would just change to a high viscosity fluid
 

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CL600 year 2001
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Discussion Starter #19
I have changed now to FEBI. That is working with my friend's CL600.
 
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