SBC pump confusion

[Frontstep]

When Mercedes replace with "contribution" they pay half well not a half as we know it ie 50% .
Your "half" = 100%
Mercedes special half = 0%

 

[orb the Impaler]

Incidentally, if I were doing their PR, I'd be saying: "Replace all these pumps now - end of. It's a no-brainer. The very least you can do to protect the brand."

What? You mean like they fixed all the rusty MBs back from 10 years ago to "protect the brand"? Obviously they didn't want thousands of scabrous, disintegrating heaps with Mercedes badges on driving the streets, and would prefer to honour their apparently very comprehensive corrosion warranty.

Eh? Oh? Hang on!

It makes me wonder at what age the majority of the ABC and SBC equipped cars will start being scrapped as uneconomical to repair; CLs are now approaching the "banger money" region with R230s following.

At some point - I reckon when they are in the 3-4K region - they'll be getting scrapped due to ABC pump/strut/SBC or electrical issues where these occur together. (With my SL I could seriously have just abandoned the thing in the street and walked away from it in January and not have been appreciably worse off than I was in July when I [STRIKE]gave it away[/STRIKE] sold it)

I'll wager that not many will make 15 years old and almost none will ever make 20s outside the hands of real enthusiasts.

 

[Xtractorfan]

Yes they do seem to have a 'grow out of responsibility' policy and it seems to be working for them, there are fewer posts now regarding the rust issues, but in MBs case Jimmy savile never dies!!!

 

[martin_sv]

Having recently (July) aquired an R230 I've read all the SBC related threads on this and the "other" forum. and searched through for older discussions. In an earlier SBC related thread the 10% figure has been quoted for the amount of braking force remaining when failure occurs. I'd be interested to know the source of this figure as it appears to conflict with Mercedes own technical documentation for the SBC system. ref: According to the tech info supplied by them, total failure of the sbc should leave you with hydraulic ( non servo assisted as there isn't one) brakes which achieve 0.3g deceleration with a pedal pressure of 112lb/ft (a seriously hard stamp on the pedal) and a longer pedal travel before this starts to take effect. Now that is pretty pathetic ( although suprisingly it meets the legal minimum according to mb) and probably feels similar or worse than if you try to stop a normally servo braked car without the engine running and the vacuum exhausted. The majority of road cars when tested on normal road surfaces can match 1g or perhaps 1.1g as their ultimate braking force so 0.3g would equate to 27% to 30% residual braking effect. Poor but a lot better than 10%. I still think this is totally unacceptable in any modern car when 50-75% figures have been obtained from traditional split circuit designs back as long ago as the early 70's. As mentioned by the OP the fact that at no time do Mercedes provide easy access to the information which could show how much life the pump has left is inexcusable. The reason why this overall situation persists I believe is that basically Mercedes try to divide and rule. If any one has a really close call as a result of sbc failure then as we have seen recently they may well (still) provide free replacement. Customer is now happy and much less minded to get involved in any possible action against Mercedes. My R230 is my first Mercedes and although there is much I like about it my feeling towards Mercedes as a company both in respect of their customer service in respect of this issue and the rust issues make me minded to avoid them in future. I think it stinks. (but I know I am not alone!)

 

[television]

I am sure Martin that I have the 10% figure in my files somewhere, or that is the figure that it calculates out to. You have front wheel braking only and as you say no servo, I will take a look later

 

[alexmoon]

Malcom, Martin is saying MB claim 27-30 percent and you are saying 10 per cent. Will be helpful if we could clear this up before I go on to MB. In any event, is even 30 per cent acceptable?

Another important point Malcolm. Can you confirm that message on white cluster DOES give you warning that pump is nearing end of its life? I was under impression - perhaps stupidly on my part - that it just goes with no warning (bright red). This is crucial.

In effect, if there is a warning procedure in place then that changes things considerably in MB's favour.

 

[mej]

With regards to the servicing requirement ipmosed by MB before they will consider a contribution; does this apply to the SBC fluid change every 2 years, which would be a reasonable requirement by MB from an engineering point of view? Or is it simply a marketing/blackmail driven requirement that you let the dealer carry out all servicing according to the ASSYST schedule?

 

[toby1]

Malcom, Martin is saying MB claim 27-30 percent and you are saying 10 per cent. Will be helpful if we could clear this up before I go on to MB. In any event, is even 30 per cent acceptable?

Another important point Malcolm. Can you confirm that message on white cluster DOES give you warning that pump is nearing end of its life? I was under impression - perhaps stupidly on my part - that it just goes with no warning (bright red). This is crucial.

In effect, if there is a warning procedure in place then that changes things considerably in MB's favour.

I believe (from reading all the other threads on this subject), there is a 1st warning of "visit workshop". Then there is a 2nd warning in red "stop driving immediately" - or words to that effect

 

[alexmoon]

If that's the case then MB will make a spirited defence of the system along the lines of "It's a wearing part with a limited shelf life and the driver is given a warning of when it should be replaced blah blah blah..."

What drew me to this was the notion there was no warning other than when it failed and you were left with 10 per cent braking only. Appears not to be so.

Only other issue then would be cost of a replacement. I am assuming some third party supplier will be working on a much cheaper pump than MB's.

 

[television]

Yes we get car all the time where the message in white comes up, usually for when the pump is not reaching the correct pressure per running cycle, in most of these cases the pump has been replaced,or needs to be replaced as the car is put on STAR to check the running time or what ever.

The ABC does a self check every 16 operations

When the dash is red, then the system has failed

I believe that the 10% was calculated by someone on Benzworld, it requires a pedal pressure of 500n (112lb) to achieve the 0.3g. The fact is the car at speed will have travelled some considerable before the driver realizes that excessive pressure has to be applied to get any braking effect at all. The few that have had failures have commented on the stopping distance, and how they have managed to stop.

The life of the pumps is the hard thing to work out, a car with Distronic will use the brakes all the time to keep the set speed, so by rights the pump should have a shorter life by my thinking, Why some pumps only cover a small mileage and others double or more is a hard question

 

[Triv]

If that's the case then MB will make a spirited defence of the system along the lines of "It's a wearing part with a limited shelf life and the driver is given a warning of when it should be replaced blah blah blah..."

What drew me to this was the notion there was no warning other than when it failed and you were left with 10 per cent braking only. Appears not to be so.

From what I've read on this, on this forum, recently, I don't think it would be unreasonable to argue that these vehicles are now second hand. It could therefore be assumed that unscrupulous vendors could sell the vehicle after the white warning but before the red.
I suggest that leaves Mercedes with no defence whatsoever.
I must also add that all I know about this system comes from comments on this forum and so do not know how it works...

 

[Gkinghorn]

I am also pretty sure at least 1 member here it went straight to red..no white at all.

 

[martin_sv]

I am also pretty sure at least 1 member here it went straight to red..no white at all.

I'd back this up and also on I believe the "other" forum one owner had his replacement pump go "straight to red" within 6 mths. This lack of any warning is I would suggest what we're all most concerned about. Mercedes approach to this seems way out of line to their normal high regard for safety in design and maintenance. Not one mention in any service at any mileage or time period is made in respect of for example " check current SBC pump life status - advise customer" .
Compare this with again just for example something like a cam-belt change (other makes). These are seen as consumable items (albeit long life) and instructions to replace at a certain time or mileage is the norm. Importantly prior to this there are instructions to check condition and report anything out of expectation in regard of visual condition. A clear example of the precautionary principle in action.
Mercedes customers are just left in the dark ( as may be their servicing agents). The implications of cam-belt failure hurt the customer financially, the implications of brake failure seem not to bother Mercedes. This ommision shows mercedes in a very poor light.
Just a bit of maths on the claimed 0.3g residual braking after SBC failure. Assuming a 1.0g maximum braking effort. Stopping distances are increased by a simple multiple of the relative differences in deceleration
i.e 1g/0.3g= 3.333. So normal emergency stopping distance 10 metres at 1g will produce a stopping distance of 33.33metres at 0.3g and so on. So 30metres becomes 100 metres, 50 metres becomes 166.66 metres. This does not include any additional distance covered whilst the driver presses the pedal and finds it travels significantly further before any braking effect starts happening.

 

[Xtractorfan]

Your mathematical calculations do not take into consideration the amount of sheer panic experienced by the driver who has the misfortune to try and stop this missile in a crisis... It wouldn't be so bad if he had a decent handbrake to fall back on..

 

[martin_sv]

I agree!!

 

[toby1]

Playing devil's advocate here for a sec: if this was a major safety issue, wouldn't there be a safety recall upon the insistance of DoT via DVLA?

 

[martin_sv]

I believe its VOSA who are the relevant agency.
There are two references to the SL and E class betwee 2001-2012 in respect of braking.
Reference : R/2004/094
Manufacturer Ref : p005
Make: MERCEDES BENZ
Model : E Class and SL
Launch Date : 05/07/2004
Numbers Involved : 39742
Build Start Date : 01/06/2002
Build End Date : 01/06/2003
Recall Details
Concern : POSSIBILITY OF REDUCED BRAKING EFFICIENCY
Description : Premature wear of the Sensatronic Brake Control (SBC) unit may lead to a reduced braking efficiency
Remedial Action : Recall affected vehicles, download the latest software. Following the download, the system will advise when the SBC hydraulic unit requires replacement.

AND

Reference : R/2005/134
Manufacturer Ref : P036
Make: MERCEDES BENZ
Model : E CLASS AND SL CLASS
Launch Date : 27/07/2005
Numbers Involved : 4700
Build Start Date :
Build End Date :
Recall Details
Concern : BRAKE PEDAL MAY REQUIRE MORE EFFORT THAN EXPECTED
Description : Problems may occur with the Sensotronic Brake Control (SBC) hydraulic unit that could affect the input required by the driver to stop the vehicle.
Remedial Action : Recall the vehicles that are likely to be affected so the SBC hydraulic unit can be checked and if necessary replaced.

So best to check whether your own vehicle has had both of these inspections. I called the original servicing dealer and he could only find the first for my car . Think I might give MB Milton Keynes a call.

I've seen a statement from MB which appear to play down the issues. They state that the problems only occur with exceptional high mileage usage and mentions taxis. I think forum members experiences over the years suggest otherwise.

 

[television]

Your mathematical calculations do not take into consideration the amount of sheer panic experienced by the driver who has the misfortune to try and stop this missile in a crisis... It wouldn't be so bad if he had a decent handbrake to fall back on..

This is the important bit, and at 70 you cover a fair distance before it sinks in

 

[television]

I believe its VOSA who are the relevant agency.
There are two references to the SL and E class betwee 2001-2012 in respect of braking.
Reference : R/2004/094
Manufacturer Ref : p005
Make: MERCEDES BENZ
Model : E Class and SL
Launch Date : 05/07/2004
Numbers Involved : 39742
Build Start Date : 01/06/2002
Build End Date : 01/06/2003
Recall Details
Concern : POSSIBILITY OF REDUCED BRAKING EFFICIENCY
Description : Premature wear of the Sensatronic Brake Control (SBC) unit may lead to a reduced braking efficiency
Remedial Action : Recall affected vehicles, download the latest software. Following the download, the system will advise when the SBC hydraulic unit requires replacement.

AND

Reference : R/2005/134
Manufacturer Ref : P036
Make: MERCEDES BENZ
Model : E CLASS AND SL CLASS
Launch Date : 27/07/2005
Numbers Involved : 4700
Build Start Date :
Build End Date :
Recall Details
Concern : BRAKE PEDAL MAY REQUIRE MORE EFFORT THAN EXPECTED
Description : Problems may occur with the Sensotronic Brake Control (SBC) hydraulic unit that could affect the input required by the driver to stop the vehicle.
Remedial Action : Recall the vehicles that are likely to be affected so the SBC hydraulic unit can be checked and if necessary replaced.

So best to check whether your own vehicle has had both of these inspections. I called the original servicing dealer and he could only find the first for m car . Think I might give MB Milton Keynes a call

I had both these recall on my SL, in the first case the pump was made to run longer on each operating cycle

 

[television]

Nothing in life, including life has any warning system that can tell you a failure is coming up