E55amg0220

So for a while now Ive known that my car needs a new accumulator on the SBC motor. But hasnt caused a huge issue and since the SBC motor is new and has a low count, i had it checked, figured Id order the part and do it myself since its only 98 bucks and they want a 1000 to do it. Anyway no big deal the brakes have always worked fine and ive had no issues but had a weird thing happen today

So I went out and turned on the dash to check oil level and then popped the hood to check it manually with the dipstick as well. I then went through an was checking the coolant and lil things here and there like I always do. The key was turned to the on position but the car was not running. Anyway everything looked great hopped in and turned the car on no probs and as i hit the brake to reverse the red brake light comes on and I now know how hard it is to stop using the lil reservoir, (On a side note at least i know how it feels)

So i pull back into the garage an pop the hood the brake fluid in the reservoir is boiling and smoke is coming out I dont know why, so I unplug the SBC motor, clean the fluid that overflowed, plug it back in and everything is working fine like it did before

Did a search to no avail i mean if the car had been moving or if I had used it recently and heated it up i could see this happening but the car hadnt been run for hours and the fluid was cold so .... im confused

E55amg0220

well I wasnt obviously getting any luck here haha but I started doin more research and found that the brake fluid was not boiling but venting it was the accumulator failing.

So I decided to order an accumulator from RMeuropean they had a good sale going on and there was a coupon code so all said and done it got here in 2 days for 42 bucks. Now I know my SBC was fine as I had it checked by the MB guys and the count was way low they said it was the accumulator.

Its been driving fine other than the lil annoyance of the brake system needs attention light when I start the car and the loud SBC motor coming on when i start it. Well then I got the above weird thing started and got me real worried. But today I had a BIG scare driving on the freeway home the RED light comes on with a beeping sound saying brake failure stop car and I got to experience how much of a joke the back up system is. An being im also an minor league bodybuilder and can leg press over 1300 lbs it was still a PITA to get the car to stop. Seriousy what jackass designed a 500hp car to have such a POS backup braking system.

So I called the MB and talked to the service manager and asked what he could do to help out. First off they want 4 hours to remove install and bleed, to the tune of 750! I know the bleeding takes time bout an hr and half but seriously removing and installing should take mins.

I read many posts not many people had much experience with changing one without an SDS which im saving up for. So the part got here today just after the brake failure .... which if I stopped the car and then restarted it it would be normal for a while so I was close to home so i limped it home. I was reading and I was like ok what the hell is the difference if I just unplug the SBC and let the system go to sleep and then I covered the SBC motor with a thick towel and was able to slowly turn the accumulator and let the thing depressurize took about 3 mins then unscrewed it moved it through the brake lines easily and put the new one on and tightened. Cleaned it all up and then plugged the SBC motor back in and turned on the key. It ran for a lil longer than normal but after it stopped no brake light took it for a ride ... brakes feel much better than before. So I will take it to my buddy at MB an he said he would do the brake bleeding for 75 bucks with his SDS and clear the code.

So I saved myself round 1100 bucks cus they wanted 1200 for the part install and bleeding. I bought the bosch correct part for 42 and it will be bled for 75.

tw2

There are cheaper options than SDS for disabling the SBC and de-pressurizing, carsoft MBII would be one. Glad you got it sorted. I could find this from searching but hope you don't mind- when the SBC count is up, do you have to replace the entire metal block?



Or just parts inside it? Would this not come with a new actuator? Which I presume is this?

BoostedAero

Yea, this sounds like a pretty scary example.... I have a low count too and always have SBC in the back of my mind as a worry.

To my understanding and experience when you go into the SBC in STAR/SDS you have a "Pentosin Pressure Test" you run to test the pressure built by the system to actuate the brakes.

The tolerable range is 69 Bar to 92 Bar (I think) if your pressure lower than 75 and the pump runs loudly before startup your accumulator is failing.

You would need someone to actually pinpoint the hard count on the SBC in Dev Mode of SDS to get an estimate of how much longer you have before the 300,000-500,000 actuation count is reached where it fails and gives you a red screen of death.

I find it really interesting that you could just unscrew it then screw it back in and it worked just like that while the thing was asleep.

How much fluid did you add once the system was pressurizing after you replaced the accumulator?

I am due to replace mine sometime soon as well. It is on the shelf in a box calling my name after reading this thread lol

E55amg0220

Yeah im with you I dont like the SBC crap either ... I wish they had some sort of conversion thing that can be done to get rid of this. I am not a fan at all ..... since you nvr know when its going to fail ... what happens if it happens while your doing a hard acceleration run?? Almost seems like this could be a big law suit considering how hard it is to stop the car when it fails.

Honestly it didnt take hardly any fluid at all which I found weird.