Cl500 abc problems

[brandwooddixon]

I got my hydraulic lines repaired basically and they made the rear left side about 3 cm longer and it did take me time to get it into angle to screw it into the valve block do you reckon that might be the issue I was thinking of disconnecting it and try and see what the pressure would be id assume there wouldn't be any but would it be worth the try? Or getting the pipe shorter by 3cm

Are you certain that there's not a kink in the pipe?

 

[cl500:/]

Are you certain that there's not a kink in the pipe?

No kinks I checked everything its just 3cm longer that's all I will go under the car today hopefully to check some more wirings and I'll triple check the piping

 

[Richard Moakes]

I got my hydraulic lines repaired basically and they made the rear left side about 3 cm longer and it did take me time to get it into angle to screw it into the valve block do you reckon that might be the issue I was thinking of disconnecting it and try and see what the pressure would be id assume there wouldn't be any but would it be worth the try? Or getting the pipe shorter by 3cm

I would try that, flow rate is low, but pressure is high, so safe to discharge the line into a bucket

 

[cl500:/]

I would try that, flow rate is low, but pressure is high, so safe to discharge the line into a bucket

Thanks will try that

 

[ajlsl600]

Unless you really kinked it I doubt it. those pressures will find their way thru, if anything at all u may have reduced flow, but I doubt that
I think you likely have a valve block issue. Its well known. But do check ur relief valve as higher than design press can bring about a multitude of other issues, such as blowing Downstream seals esp anty that are not in best of condition

 

[cl500:/]

Yeah the rear valve block doesn't hummm or hiss even that black ball on it I don't feel any vibrations so I think it's something to do with the rear valve block also bought 4l of Mercedes hydraulic oil £98.88

Unless you really kinked it I doubt it. those pressures will find their way thru, if anything at all u may have reduced flow, but I doubt that
I think you likely have a valve block issue. Its well known. But do check ur relief valve as higher than design press can bring about a multitude of other issues, such as blowing Downstream seals esp anty that are not in best of condition

 

[LostKiwi]

There are two ways the system controls pressure.
1st is via the suction valve built into the pump.
2nd is via the pressure supply valve.

The pressure supply valve is the unit with the pulsation damper and is there to limit the maximum pressure in the system.

The suction valve is integrated into the pump and opens when supply pressure is too low and closes when operating pressure is reached effectively strangling the pump.

From my notes:
These three components are grouped together into the same assembly. They are the first set of components immediately after the pump.

There is a pulsation dampener(52a) attached to the assembly, part number 2203270215. It is a black sphere. It is similar in design to the other three accumulators in the system (nitrogen gas behind a rubber membrane), but much smaller. Since the fluid flow from the pump is "choppy" given the nature of its design, something is needed to smooth out these waves or vibrations in the fluid. This is the job of the dampener. Air behind the rubber membrane acts as a cushion and evens out the pressure, much like a gas shock absorber removes road vibration.

There is also a pressure limiting valve (52b) integrated into the assembly. It is a passive device, not actively controlled by the control module. It will open when the pressure exceeds its designed limit (~200 bars), allowing any excess pressure to be bled off. Its job is to help regulate the system pressure.

Lastly, there is a pressure sensor (B4/5) attached to the assembly, and it is wired to the control module. A resistor inside the sensor alters the voltage passing through the sensor based on the amount of pressure applied to it. At zero pressure the voltage is around 0.6 volts. At full pressure it is at 5 volts. The control module monitors this voltage, and infers the system pressure from it.

Integrated into the pump is a suction restrictor(Y86/1) or throttle valve. It is wired to the control module and open and closes based on the voltage supplied to it. The opening and closing of this valve controls the rate of flow from the reservoir into the pump.


If you are seeing in excess of 200bar that suggests one of two things:
1. The pressure sensor is giving a bad reading.
2. The pressure supply valve unit has failed and is not regulating pressure.

It could also be a blocked low pressure pipe on the outlet of the pressure supply valve but that's unlikely.

Here's a diagram.


Pressure supply valve is 52 and pump (with suction valve) is 1. Note the suction valve is under ECU control but the pressure supply valve is a passive device.

 

[cl500:/]

There are two ways the system controls pressure.
1st is via the suction valve built into the pump.
2nd is via the pressure supply valve.

The pressure supply valve is the unit with the pulsation damper and is there to limit the maximum pressure in the system.

The suction valve is integrated into the pump and opens when supply pressure is too low and closes when operating pressure is reached effectively strangling the pump.

From my notes:
These three components are grouped together into the same assembly. They are the first set of components immediately after the pump.

There is a pulsation dampener(52a) attached to the assembly, part number 2203270215. It is a black sphere. It is similar in design to the other three accumulators in the system (nitrogen gas behind a rubber membrane), but much smaller. Since the fluid flow from the pump is "choppy" given the nature of its design, something is needed to smooth out these waves or vibrations in the fluid. This is the job of the dampener. Air behind the rubber membrane acts as a cushion and evens out the pressure, much like a gas shock absorber removes road vibration.

There is also a pressure limiting valve (52b) integrated into the assembly. It is a passive device, not actively controlled by the control module. It will open when the pressure exceeds its designed limit (~200 bars), allowing any excess pressure to be bled off. Its job is to help regulate the system pressure.

Lastly, there is a pressure sensor (B4/5) attached to the assembly, and it is wired to the control module. A resistor inside the sensor alters the voltage passing through the sensor based on the amount of pressure applied to it. At zero pressure the voltage is around 0.6 volts. At full pressure it is at 5 volts. The control module monitors this voltage, and infers the system pressure from it.

Integrated into the pump is a suction restrictor(Y86/1) or throttle valve. It is wired to the control module and open and closes based on the voltage supplied to it. The opening and closing of this valve controls the rate of flow from the reservoir into the pump.


If you are seeing in excess of 200bar that suggests one of two things:
1. The pressure sensor is giving a bad reading.
2. The pressure supply valve unit has failed and is not regulating pressure.

It could also be a blocked low pressure pipe on the outlet of the pressure supply valve but that's unlikely.

Here's a diagram.
View attachment 86600

Pressure supply valve is 52 and pump (with suction valve) is 1. Note the suction valve is under ECU control but the pressure supply valve is a passive device.

Thank you so much for this information and everything, so the first thing I will do tomorrow is lift the car up and have a look to see if there is a kink which I'm sure there isn't any, second I will remove the rear left hydraulic line from the valve block because I suspect something wrong there and see if the pressure decrease, after that I will check the pressure sensor does it have a specific resistance reading? If not I will check the power to it, then I will check all the wires at the abc module then I will change the hydraulic fluid if nothing goes to success I will be sending it to the Mercedes specialist I did ask the dealership about this specialist and they approved him to be good also do you know the location of the pressure sensor ? I saw a sl500 on the ground at the dealer looked slammed and sitting there for a while poor old car looked quite similar to yours won't let me upload a picture of it here says its to big but anyway
I appreciate everyone's help alot like really I mean it thank you all so much for this wonderful people

 

[LostKiwi]

Here are the front locations. Just be aware they may be reversed.

 

[cl500:/]

Here are the front locations. Just be aware they may be reversed. View attachment 86601

Thank you so much lostkiwi I appreciate it alot thanks

 

[cl500:/]

Hi all once again,

So today I lifted the car up and checked for kinks and I can confirm there are no kinks,
I removed the pipes from the rear valve block the ones that go to the struts I can also confirm I am not getting any fluid past it I'd say it gets about 50ml or less of fluid after that I drained the fluid from the reservoir and put the original oil took about 1.8L however I think more will go in because I got alot more in the tub id say about 3 l or 3.5l, however after I changed some what of the oil I did leave it running to flow ( before I drained the fluid there height of the car was lifted about 10 to15cm above) while it was running and still in the air I checked the level sensors readings and it was reading 0.8v each wheel had different voltage can't remember it ontop of my head but yeah, I tried doing the rodeo still not able to I tried lifting each strut separately the fronts decided to drop each time I pressed f2 lift front left then when I pressed f4 lift front right it did the same thing, I watched legitstreetcars love the guys content but he had a cl65 with similar issues his had rubber in the pipes so caused some issues after he replaced and cleaned the pipes with air and connected it all back the rears wouldn't get any fluid it still had the old fluid so his front end would go up but rears nothing after he done further testing and inspection his pal had a spare rear valve block refurbished he fitted it and kaboom the rears went up then he was able to do a Rodeo and it worked so now I'm lost because I guess I have similar issues to him
Would I need to disconnect the lines at the t joint in the front to see if I have anything stuck inside the pipes not letting the fluid flow and causing the high pressure
Because after I disconnected the pipes from the rear valve block the pressure still stayed at 255bar so now what to do?

Thank you all once again I will never stop thanking you all for all the help and information

 

[LostKiwi]

First thing to check is are you getting fluid to the rear valve block? If you loosen the inlet pipe a little and run the engine does oil come out? Check the pressure too.
Then crack the bleed valve each side and try again.
If you get oil to valve block but not to bleed nipples it suggests a bad valve block
There's really not much more it can be.

You can also check to see if the pressure sensor is bad by measuring voltage. It should vary between 0.6 and 5v (zero to max). 255 sounds like a max value from a bad sensor.

 

[cl500:/]

First thing to check is are you getting fluid to the rear valve block? If you loosen the inlet pipe a little and run the engine does oil come out? Check the pressure too.
Then crack the bleed valve each side and try again.
If you get oil to valve block but not to bleed nipples it suggests a bad valve block
There's really not much more it can be.

You can also check to see if the pressure sensor is bad by measuring voltage. It should vary between 0.6 and 5v (zero to max). 255 sounds like a max value from a bad sensor.

Hi so done what you said removed the inlet pipe and can confirm it's getting fluid but it isn't passing the valve block looked inside the holes where the pipes sit and can't see any debris or anything so I suppose the rear valve block has just given up, I was thinking of buying the repair kits for the valves they just come with all the seals needed or I just just get a refurbished one on ebay for around 250£ I will go to the Mercedes specialist to tell him that the mb oil didn't do anything yeah so I suppose I should change the seals or buy a refurbished one, when I removed the pipe the pressure did not drop I did notice that the black ball under the engine behind in between the gearbox and engine it has a sensor on it, looks like the previous person broke the wires and connector because its soldered instead of having a connector I need another one of them sensors and a connector I do not know where to find it from and what it's called any help or links or part number for the connector so I can buy the connector with the wires already in it so i can do a proper job

 

[LostKiwi]

That's the ABC pressure sensor.

We have a smoking gun.

It also appears the rear valve block is bad - check the connector and give a good spray of contact cleaner. Do NOT use WD-40.

 

[cl500:/]

That's the ABC pressure sensor.

OK thank you, are they all the same ? And does anyone have a picture of the connector so I can find one at my local scrap yard to match it
Thanks again to all who have given me information

 

[cl500:/]

Is this the sensor?

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[cl500:/]

That's the ABC pressure sensor.

We have a smoking gun.

It also appears the rear valve block is bad - check the connector and give a good spray of contact cleaner. Do NOT use WD-40.

Smoking gun? What's that the connectors I've cleaned them used brake and clutch cleaner they seemed clean and I was able to activate the valves,

 

[ajlsl600]

Smoking gun? What's that the connectors I've cleaned them used brake and clutch cleaner they seemed clean and I was able to activate the valves,

Abc when behaving is a great system giving best ride, handling of any car I owned however its not much fun for you or ur wallet when it misbehaves. And filtering the oil on the return side of a very fussy system is a shxte idea doomed to cause issues eventually even with over regular oil changes. I would go as far as to say a 15 ur old abc system prob wants all flex pipes changing, esp if resealing valve blocks and or changing pump, damper. A tiny bit of rubber will likely play havoc. Eventually. Hope you. Op get sorted. Having a car stay completely flat in and out of a fast corner is quite something. Trying that in anything else would likely have you in a ditch

 

[cl500:/]

Abc when behaving is a great system giving best ride, handling of any car I owned however its not much fun for you or ur wallet when it misbehaves. And filtering the oil on the return side of a very fussy system is a shxte idea doomed to cause issues eventually even with over regular oil changes. I would go as far as to say a 15 ur old abc system prob wants all flex pipes changing, esp if resealing valve blocks and or changing pump, damper. A tiny bit of rubber will likely play havoc. Eventually. Hope you. Op get sorted. Having a car stay completely flat in and out of a fast corner is quite something. Trying that in anything else would likely have you in a ditch

Yeah this is my first time owning one I fell in love when I saw it listed on fb I was on holiday and I put a deposit down so when I come back I take it , but aye I like it at the end of the day every car will have a major issue but not like the abc system hopefully I will get a rear valve block and see if the issue goes if not then I am going to need bigger pockets , will contact the mb specialist drop the car off to him so he can do further checks as they have the lifts, if I had a 2 post lift to make life easier that would've been amazing I will keep everyone updated on the car
Still need to do mot and my front brake pads and a completely full service.
I got told they are the best systems to have but the worst when they fail. They are the best cars Mercedes made in that time c63 cl55 e63 ect... Does the s class have air inste hydraulics?

 

[cl500:/]

Found a video on YouTube this is the connector I need