timannnn

Hey guys,

I just purchased a 2006 e350 and have had it for a few weeks now. I took the car in for the sbc pump being so loud and always coming on. It's mostly when I am parked in a parking lot and run errands around town. Every time I open the drivers door or when I first start the car, bbbbbrrrrrraaaaaaaaapppppp there's the pump.

All TSB's have been done with the car at least that's what the SA told me. They did install what looks like the inline noise suppressor that is supposed to fix the problem.

My issue is it's still coming on all the time. Obviously I do not notice it as much when I am driving but every time I get into the car? Seriously it sounds like an air compressor on an RV. Is this what a 50k-60k$ car is supposed to do?

My question is do you guys notice yours this much or is it completely normal and I should get on with it.

Thank in advance.

Polar Bear

When you say all the time do you mean all the time? It should come on with about every five-ten presses of the brake pedal. If it is coming on after every press you do have a problem. Also, when the vehicle thinks it is going to be driven (unlocking or opening a door, etc), it will activate the pump if the pressure is a little low to bring it up to specs, which is normal.

Get in the car, turn on the ignition and do not start the car. Press the brake pedal as you would when slowing down in traffic. How often does the pump come on?

Instead of the brakes getting their power from your foot, they get it from the SBC pump. There is an accumulator (reservoir) that stores the pressure and this is released to apply the brakes when the pedal is pressed. When the reservoir gets down a little, the pump "fills it back up." If this is what you are experiencing, this is normal operation and is not a cause for concern. If you are looking for it all the time you will notice it.

TPAbnz

As it is perpetually on and you hear it "all the time"?

Or only when you open the door? If the latter, hardly something to go ballistic over your RV "$50000 - $60000" car. Didn't your SA explain what SBC is doing? It's normal.

timannnn

Case in point. I have not driven my car all day today. About an hour ago as I got into the car and opened the drivers door the pump goes on for around 5 seconds and it's loud. I drive two blocks to starbucks and park. I am in there for about 5 minutes. As I get back into the car and start it the pump goes off again. This seems excessive to me.

AMGTTV8

that's part of the programing of the pump...

every time the drivers door is opened the system primes itself for use, as if the driver would be getting in the car to drive away. unfortunately the car has no way of delineating between when you are opening the door to simply get something out or when you are actually getting in to drive.

hence why on all cars with sbc, such as the sl, doors can not be opened during the installation/removal of brake pads and rotors as it can cause injury to the technician through the build up of break pressure, leading to clamping down of the brake caliper.

nothing is wrong with your car, you just have a sophisticated braking system

hope this helps alleviate your frustrations!

chris

timannnn

Here is a video of the sound it makes. Let me know if it is similar to any of your cars. All you have to do is get in the car and depress the brake pedal 2-10 times for the pump to come on. No key required.

velvet fog

The behavior is normal. The SBC pump supplies all the hydraulic pressure to the brakes so it operates regardless of key position. With the engine and key off, the pump should operate for a few seconds every 3 presses of the brake pedal.

The only issue I see is you think the pump is too loud. Kinda hard to diagnose over the internet.

MARK CUMMINS

Thats Normal....

As the SBC is Primed when you open a door or pump the brakes

Yacht Master

Worry when you don't hear it.
To me it sounds like the TSB ground strap was installed wrong and is telegraphing the pump noise to the inner fender support. Or when "muffler hose" was installed it was done incorrectly (air introduced). Be careful who you let service your SBC #1 you can't do anything correctly with out SDS. #2 SBC is the most complex braking system on earth, it counts every brake application, pressure, and records it, it is significantly past the abilities of most techs even at Mercedes Benz dealerships. The upside, if you maintain your electrical system (both batteries) and follow instructions and early warnings in the MFD, SBC will serve you well, and it is covered by an extended warranty (ground strap caused this).
I have one question for you, What about all the other noises? I hear no less than 12 items "getting ready" before I even start the engine.

K-A

That does seem way too loud to me too. Although I never stick my ear under my front bumper, I'm pretty sure my car doesn't buzz that loud....

SAguirre

That does sound much louder than my pump. Way louder. Also, even if I leave my car parked for 4 weeks, when I get in my car I only hear very faint clicking sounds, some hydraulic squirting-like sounds (very very faint though) and a very high pitch sound that most people can't hear. The pump only turns on about once in about 20 times that I go to my car and open the door. I have gotten used to it and I have gotten to like it. It is as if the car is waking up and I know that all is OK with it. When I get into my Audi, I always wonder if the battery is dead now since it does not make any sounds. If I want to turn on the pump, it takes about 5 times of pushing the brake pedal down for it turn on (this is before I even start the car).

I had all the SBC stuff done, the pulsation damper made it very quiet! I think that you should keep perusing this; I don't think that it should be turning on all the time like that, the accumulator might not be holding pressure quite well enough.

Just my thoughts,

Steve

vettdvr

Mine was really quiet. SBC made no noise. However the red flag in the FSS indicating STOP Total Brake Failure.

On the tow truck there wasn't much noise from the pump either.

lapok25

It is normal everytime you open your door or disarmed the car but I think yours is too loud or it is because it is inside the garage. Mine is noticeable when the car is inside the garage, but outside not really.

timannnn

Thanks Steve,
Yeah I took the car to the dealership this morning. They brought the tech out to look at it before they took the car back. The tech says "completely normal". I looked around for a car like mine with the sbc (there was one parked near us) and I asked the SA if we could simulate the noise with the other car. Sure enough as soon as the pump came on it was dead silent. Just a muffled pump noise barely noticeable. So a side by side comparison was done in front of the tech and the SA. Needless to say they took the car in. Funny thing was that the other car was exatly like mine, same color, year, options.

Also I don't know if you guys know this but if the pump ever malfunctions it's almost impossible to stop your car. Even the tech reaffirmed this. Even at 30-40mph you have a tough time just slowing down without the SBC operating. This was my concern. How would you know if the pump was going bad? Loud noise, going on constantly, etc? I don't know but I did not want to take a chance on it.

Will let you guys know what happens.

vettdvr

When it fails you get a big red "TOTAL SBC BRAKE FAILURE STOP CAR" in red in the FSS. Unfortunately I would assume the computer thinks you are on a NO traffic road. Now,, ask how I know!.

For the record,, I will NEVER buy another car with total electronic SBC type braking.

K-A

I love the way SBC feels, and I think it's a great technology in theory, but the thought that my Brakes could fail has me definitely not feeling that great about it, I think things like Brakes should be left to the old reliable "old tech" as long as it works alright, no need to sacrifice our livelihood.

AMGTTV8

even if the system goes out there is still a back up system which works off of manual pressure...it doesnt mean you dont have brakes when the light comes on, it simply is letting you know that the computer is no longer helping you

Barry45RPM

... and you pretty much can't stop the car. Great Idea in theory, not so good in the real world, discontinued in 2007 MY cars.

vettdvr

Correct, without SBC very high pedal pressure and very long stopping distance. Yes you can stop,, the question is will it stop before being stopped.

Miguel

Hi! my 2003 w211 220cdi keeps the pump on too much time after the key is turned. the car is not starting, seems that some pressure or level is not reached and ECU do not strat the car.

is there any scheme of the sbc system we can use to check for leaks ?

vettdvr

How much time is too much? Can you use a stop watch to measure seconds. ? But from your note I understand the engine doesn't start either. The SBC is independant of starting the car. If your car is not starting you have other problems. When my SBC system totally failed the engine would still run and the car could drive,, granted very poor brakes.

I would look elsewhere to find why the car doesn't start.

Miguel

well, the pump runs for 60 sec or more if the key is on the 2nd position (before ignition). In matter of fact, I do not know if that small black pump in front of the SBC is a part of the SBC system. That is the pumop that keeps working.

Conserning the fact that the car is not working, I'm trying to understand what's happening, today I changed the diesel filter and checked if the diesel reaches the HP pump what is afirmative.

Thanks for the help.

vettdvr

Are you sure it is the SBC pump and not the air/suspension pump leveling the car. My air/pump will run about 60 seconds also at start up. Didn ' realize you had a diesel. Thought it was a gas burner. I have a diesel truck and you must have glow plugs that preheat prior to start. I assume the Mercedes does also. There is normally a relay to turn on the glow plugs and this is a common failure. Also on the crankshaft/camshaft is a cps that triggers the injector pump to fire, if this fails the engine won't start either.

Miguel

well, i guess it's a circulation pump for the heating system, probably works when the rest button is pressed and some other times (eg when driver's door opens).

i would not bother too much if somebody tells me it does not relate with the fact that i can't start the engine...

Diesel Benz

The motor at the SBC system (ABS on older cars or what ever you call it), where all the brake lines go, is the one that runs when you open the door. You probably have identified the right part for the SBC pump and it just is running too much.

Don't you get any malfunction messages? If you do not, the SBC pump should not prevent the car being started.

If your engine cranks but does not fire, that again could be a high pressure CDI pump issue, leakage somewhere or just worn out pump (how many miles does the car have), it could be injectors too. The ECU will not inject fuel before the rail pressure is high enough!