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So it sounds like you have a fluid starvation... or big leak when moving.

52 has a spring contolled check valve parallel to pressure relief valve; is that changed/checked. Also there is spring check valve in near temp sensor is return line pressure ensured? It is not said how much tank pressure should be, but I assume it is several bars since there is also accumulator 53 in tank line. And only thing that keep tank line pressurized (= accumulator has any use) is than check valve. Has 53 any pre charge or tank line required pressure mentioned?
 

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Discussion Starter · #102 · (Edited)
52 spring valve is inside the block and not ment/possible to replace. It leaks the pressure peaks above 200 bar to return line. I have changed the entire block to a refurbished one and yesterday changed it back to original - no difference.

The return line has low pressure - if I remember right it is 10 bar. If exceeding that, it will return to reservoir. The reservoir us open to atmosphere to let air come out. That pressure leak on that return line will not affect on operation pressure; if it would, the leak would be already before that some where in the system - and its spring is weak to keep any pressure of that high.
 

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Discussion Starter · #103 ·
Maybe I will connect an outer power source - a 6 V battery - to the throttle valve just before the pump (inside the pump actually) and operate the throttle valve by a controlled way using a switch.

That way I should see if the pressure raises when I open the throttle valve.

Anyhow the pressure relief valve will cut the pressure at 200 bar to protect components.

I can see the pressure all time on screen. But what could be the outcome?

Pressure raising to 200 bar when manually opening the throttle valve would mean that the pump is OK. If that raising to 200 bar will happen even, when the system has low pressure - 150 bar - it should mean that there is a leak, or the control unit does not open the throttle valve, as it should do at that level of pressure. Right?
 

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Green line check valve spring IS that part which keeps green line pressure up (10bar?). Low pressure line usually will effect to high pressure; relief valve is acting as a pressure difference point of view. Set pressure is usually between green line <--> purple line. So 5 bar dropping in green line would cause approx. 5 bar drop (there can be some area ratio) in purple line. Since pump is fixed displacement, pressure relief valve is always letting through some fluid. Flow of the pump is controlled by that throttle valve (cavitation control), like known,

Is it really a 6V system? I would thought its 12V.
 

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Discussion Starter · #105 ·
"Is it really a 6V system? I would thought its 12V."

I am not sure what is the Voltage - I just tested that it opens with 6V and do not want to give more than needed. It works with 6V - it is just simple solenoid with plus and minus cable. Often the control voltage is lower than 12 V.

Yes - I understand that the counter pressure in low pressure lines may give higher pressure to the high pressure line. I will check that pressure also, no prob, but going down to 150 and so - that should not be because of the low pressure line, even if there is 0 bar.
 

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Throttle Valve is a proportional valve - spool position is dependent on current fed to the solenoid. 5V sensors and components are common (TTL) but usually 'high power' components are 12/24V. In offhighway vehicles those valves commonly take up to 2A current.
 

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spool position is dependent on current fed to the solenoid.
I'm totally confused by all this, I admit I've never had to go this in depth with any of the (currently 3) ABC Cars on my books.

The old V12 CL has been by far the most troublesome, and has had both VB's overhauled, full fluid and filter. Then a burst rear pipe, (metal part corroded). That resulted in me replacing every rear pipe and accumulators, plus both front to rear brake pipes and some fuel pipes whilst the Rear Subframe was out.
It has also had one strut and one height sensor. It's ABC has since been trouble free for at least 3 years ;)

I always understood that "proportional" components on MB, like Throttle Valve on ABC, Inlet Manifold Throttle Butterfly, ABS Valves, Cooling Fan, some EGR's and also Gearbox Solenoids, to name but a few, are controlled by a PWM signal from their respective ECU's .......

??????????????????????????????????
 

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Well basically PWM controls current (as it can also be seen/thougt as a differemnt mean voltage level). Here one quote I quickly found by google What is a Proportional Valve? - Norgren

"
How does a proportional valve work?
We can probably recall the school experiment, where applying a current through a coil creates a magnetic field, in turn attracting (or repelling) magnetic material. This is the basic solenoid principle.

Increasing the current increases the strength of the magnetic field and, in turn, the force of attraction (or repulsion) on the magnetic material. A proportional valve has a geometry to ensure a constant field strength, at a given current, over the stroke of the magnet.

Also, a spring is introduced to counter the force of the magnet; as the spring is compressed by movement of the magnet, the spring reaction force increases until it balances the magnetic force and movement ceases. If the current is increased, the magnet (solenoid) moves further against the spring, until the forces are balanced again. Consider that the magnet is attached to a spool in a valve, the pressure or flow can be controlled in proportion to the current applied to the solenoid.


"
 

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Right, I get you, so it is not like a bigger version of the Solenoids in a Transmission, it is more like a Throttle Valve but controlled by a Solenoid against a Spring rather than a Motor ???????????????

Like I said, never had to get involved so I don't have a clue really as I've never seen this part you guys are talking about ;)
 

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Since the spool valve is integral to the pump, and he’s replaced the pump three times, what are the odds of three successive, bad valves that exhibit precisely the same failure mode?

It doesn’t make sense.
 
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Since the spool valve is integral to the pump,
Thanks, I hadn'r realised that, I have done a couple of Pump changes over the years, but now I know that, yes, there is more chance of winning the lottery than 3 successive parts with exactly the same issue ;)

Could be the wiring between that part and the ABC Module tho, especially if SDS has reported the same issue all 3 times ;)
 

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Right, I get you, so it is not like a bigger version of the Solenoids in a Transmission, it is more like a Throttle Valve but controlled by a Solenoid against a Spring rather than a Motor ???????????????

Like I said, never had to get involved so I don't have a clue really as I've never seen this part you guys are talking about ;)
Yeah, proportional solenoid can be stopped at finite mid positions, on/off solenoid (there is also usually spring) has basically only two stationary positions, on both ends. (Flow forces can actually move the spool and even shut it totally but lets not discuss it here).

Then there are servo valve called valves, where spool has position feedback, and spool exact position in ensured by external controller/electronics (servo can have also hydromechanically feedback). But no more that item either.

True, OP has changed everything several times, therefore this is really interesting topic which I am messing with my comments even I don't have ABC car or even airmatic W220 anymore :)
 

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With the multitude of components replaced, I believe component malfunction is less likely. Not impossible, but less likely.

For that reason, I’m thinking wiring fault between control module and suction valve.

If the wiring is faulty, then there is no signal to the inlet/spool valve, so that as the fluid warms up and becomes less viscous, the pump cannot compensate by opening the valve and the pressure drops.

Same symptoms with each new pump, and new pressure regulator, and new controller, because the signal isn’t getting to the valve.

Supposition, but it explains the situation.
 
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Discussion Starter · #114 ·
The throttle valve is getting signal at least when its connection is cold - because all work well when cold.
But after some 15 min the power is some 140 bar... Pretty much steady. That could be because of bad soldering at Control Unit - the wire, which gives the signal to the throttle valve.
How to test; I will give to throttle valve 6 V and monitor the pressure.
 

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Discussion Starter · #115 ·
Today again something new:

I noticed that the pressure shown when doing the sensor calibration is extremely low - only appr 22 Bar at lowest after a while, when warm ! And when repeating that test - even when all is cold, the pressure is the same low! - on screen below it was 69 bar, when cold But where does it get that pressure value?

Well I jumped with Diagnosis siftware to the pressure sensor values; and there it was showing the same figure! I had never seen below 100 bar figures - and now firdt time. And it alweays shows that same low pressure, when I go top calibrate the sensors. This is as Poltergeist - where is the priest; as my son read from a discussion about ABC - weird and spooky!

He are the figures on photo. But why the pressure is so low, when starting to calibrate the height one by one? And at the same time even more weird: The buttons to raise or low the strut are from F2...F8 or something. These buttons only open the solenoid and the corner goes down; each one! I cannot raise them at all! Are they all leaking like a hell? But when I turn off the motor, I can get the 173 bar on screen, if I just go and measure the pressure sensor value and do not raise the individual struts with Diagnostic tool.
2689956
2689958
 

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Struts go down beacuse you don't have enough pressure to keep car up (50bar is not enough). Car tries to rise it, but flow actually escapes fron struts to pressure side where pressure is lower than inside struts- WHY it goes down only when engine running, I can't say for sure. So it must be some elctrically controlled thing. Looking circuit there is none, except that throttle valve. BUT is should be able to do it eventually, IF it can do it at steady state (slow pressure rise is also sign of delivery problems,pump is filling accumulator). In theory strut control valve could be leaking to tank line when it is actuated, but usually it is not possible such 3/3 control valve (there is no direct opening from pressure to tank. Well spool broken, maybe, but highly unlikely.
Throttle control valve test could give some insight.
 

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Discussion Starter · #117 ·
I think I need to connect the pressure gauge back and see, if that pressure really drops, when I start to adjust the level sensors. If that happens, then the reason can be really in one of those operation solenoids or valve block.

Is it so that when the car is running, but not moving, the pressure is hold by the locking solenoids? I have been assuming that it stands on the operation solenoids. That could explain the pressure drop when actuating the operation solenoids; in case they leak.
 

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Normal running solid system:
Car running, y1's and y2's not energized (spools in mid position), oil flows via 52b or parallel spring loaded check valve. Pressure is lower of either of the fixed set values (probably 52b). I still can't quite understand why there is that check valve, does 52b fail so often that they need emergency relief function?

Flow is controlled by throttle valve Y86/1

When any of y1 or y2 is actuated (and locking valve y2/y4) opened, pressure is strut pressure defined by car weight on that strut (lets forget pressure drop caused by flow), pressure remains on that level as long as strut is moving. When strut comes on end stop, pressure rises again at 52b set pressure. Same thing if y1/y2 is closed.
 

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If pressure remains much lower value than strut pressure (Are you able to put gauge between valve block and strut when strut is at mid position?), it means that flow must have a easier passage to tank. If pump has delivery problem, quite smaller leak can cause same thing, leak is larger than pump flow and pressure does not rise.
 

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Discussion Starter · #120 ·
PROBLEM SOLVED!!!!

I changed the both two aluminium valve blocks in ABC-system - one at front and one at rear and all problems were solved! I got these from ABC-specialists in Netherlands. The pressure raised immediately to 200 bar and returned to 197 bar, where it stayed steadily 30 mins which I was testing it in garage! Looks to be that one of these blocks had internal leaking issue.

Huh! It took only 13 months to solve it. Thank you guys in changing ideas! I think it is difficult to find out that kind of issue with measuring; or is it?

This week I will test it more and do the calibrations again to see that all the functionalities work perfectly.

It looks to be that I have now fixed THE CAR!
 
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