One brake job down, now rears to go. Took a little longer than I was expecting, but that was due to the learning curve. I knocked the second wheel out in about thirty minutes, but that was after spending about two hours on the first. That time frame includes a couple of runs to the store for an 18mm socket, a 3/16 hex socket, and some locktite.
Rotors came off with a little help from the hammer, but still relatively easy.
Overall, I would do again in a heartbeat, so anyone on the fence, make sure you have the right tools and roll up your sleeves. Good luck.
Thanks to Greg for his help and his DIY - made it a doable job.
Great how-to for doing the brakes. One newbie question. Where the heck are the jacking points for using a floor jack and then where do I put the jackstands? With these newer cars, it just gets harder to find a good jacking point where you don't "tweak" something. Failing some solid input I will default to the emergency jack in the trunk for this brake change
Great how-to for doing the brakes. One newbie question. Where the heck are the jacking points for using a floor jack and then where do I put the jackstands? With these newer cars, it just gets harder to find a good jacking point where you don't "tweak" something. Failing some solid input I will default to the emergency jack in the trunk for this brake change
Thnaks for any info
Hi, Blane.
This is always an issue. The ideal place you put jackstands on these cars is coincidentally the lift point for a hydraulic jack.
What I usually do is use the car's jack to lift it up, then I put in the jackstand. The little stock jack is actually quite good and easy to use, albeit not as easy as a floor-jack. Just be careful popping the little plastic cover or you can chip/crack the paint.
It sounds like you have a good understanding of the principles involved, but for the sake of others I'll reiterate an excellent safety rule: NEVER work under (or even partially under) a car that is supported only by a hydraulic jack. Period.
Take care and enjoy the ride,
Greg
__________________ If the only prayer you say in your life is thank you, that would suffice. Meister Eckhart
When you learn from your own mistakes, that's experience.
When you learn from the mistakes of others, that's wisdom.
When you fail to learn from any mistakes, that's government.
A few members have sent me a PM asking for more help on getting stuck rotors...well, unstuck.
Re: removing rotors, as a general rule I simply don't tell folks how to do it. And it really has more to do with a very real potential for damage or injury than anything else. Pounding away on a rotor without a proper understanding of the process has the potential to damage other parts and it can also cause the rotor to break, sending pieces of it flying at velocities more than sufficient to puncture your skin, break teeth, gouge out eyes, etc. And of course the use of torches carries its own dangers. When I help folks with their brakes in person I can teach them the proper methods but there's no way to properly explain it on a forum and be sure the person understands. As much a fan of DIY as I am, I'd far rather you pay someone to do it for you than take the chance of you being injured and then we both have to live with that.
With that understanding, then I will offer up one tip that is almost completely safe and which often will work for getting a rotor unstuck. Start on just one corner, that way you have three wheels on the ground to help keep things stable and one good jackstand in position under the one on which you are working. Then remove the caliper and the rotor lock-screw. Spray WD-40 around the hub area (use lots of it, it's cheap) and particularly at a steep angle into each of the lug-bolt holes, the goal is to "aim" the straw so that you're pointing it at the very small spot between the back of the rotor and the front of the hub. Spray in lots of it and turn the rotor a little, then spray more. Wait a few minutes and repeat the process. And then repeat the wait, spray, turn process for a period of about 30 minutes. (The idea here is to give the WD-40 time to run and penetrate and work for you; if 30 minutes is not enough it never will work.)
When the waiting period is over, put on a good pair of work gloves and take a 10"-12" Crescent wrench (also called a sliding-jaw or adjustable wrench) and fix it to the rotor where the caliper would have been so it is sticking straight away from the rotor off into the wheel well. Adjust the jaws for a firm grip and then use a rocking motion to lever the rotor back and forth (in and out). You can get fairly violent with it, just make sure you don't pull it off the jack stand or slip the wrench from the rotor. Repeat several times, then slide the wrench off, rotate the rotor about 150-160 degrees and repeat the wrench/lever process. Keep rotating that same amount and levering and hopefully that will break it loose for you.
If that procedure doesn't work, then you'll have to decide what your next step is.
I wish you all good luck with this and other DIY projects.
The main purpose of this post is to create detailed discussion and analysis of the DIY flushing of a SBC brake system. There are also some other more minor observations discussed herein. I am hoping others will read this lengthy post and have deeper knowledge and understanding of the SBC circuit and help to set me straight. I warn you now, this is a detailed analysis.
Being a new 2006 E320 CDI owner and avid DIY maintenance guy, I am diving into my first Benz maintenance with the brakes, as the fluid is a nice carmel color now. I too have the SBC system and am thankful to all those that have posted so much. I am a hydraulics engineer (25 year veteran) and been involved in many complex braking systems. I have digested the schematic that I have found here on the SBC system. With that study, I understand why Benz says you MUST use the Star Diags to flush the system. They are correct if you want a true 100% flush. To get a TRUE 100% flush and insure you have all water and dirt out, you have to use the SBC pump. HOWEVER, results that are good enough for my satisfaction (and I am quite the perfectionist) can be acheived at home with extra time and brake fluid. But we should all be made aware of a weakness in the DIY pressure bleed procedure. I would like to discuss the brake fluid and the schematic.
As discussed elsewhere in this forum, DOT 3, 4 & 4+ brake fluids are a complex mix of various types of phosphate esters and ethylene glycols. They are hydrophyllic (water absorbing) and not compatible with typical buna-N and Viton type oil seals. EPR (ethylene propylene) is the seal material of choice. Unfortunately, EPR seals swell and dissolve when exposed to petroleum based oils, so that is why it is imperative you never get even a small amount of oil mixed with brake fluid, else you are looking at a complete system rebuild. Water makes brake fluid's additives "unfriendly" to seals and metal parts. You cannot tell by visual inspection if water is present in the brake fluid. Over time, it does absorb water from the atmosphere. If you want to do a quick test (but quite revealing) to see if your brake fluid has water in it, you can perform an "old school" sizzle test. Take a piece of sheet metal and hold it horizontally with vice grips. Heat it from below with a propane torch to get it well over 300F. Careful not to get it too hot, as brake fluid will burn and smoke if gotten too hot. Using a glass eye dropper, pull some brake fluid from your master cylinder reservoir and place a drop on the hot sheet metal. If you have water in your brake fluid, it will boil out and "sizzle" on the hot sheet metal. This test is a bit extreme for brake systems however, as you should replace your fluid AT LEAST every other year anyway. If you get to the point where your brake fluid sizzles, you are not doing maintenance often enough or you live in a tropical rain forest.
Referring to the .pdf document found in the opening of this thread, I will explain why the DIY flush is not complete when done at home and the specifics of each of the valves in the schematic, as I have interpreted their functions. Note that I still have a number of questions that need to be answered to fully understand the brake system fluid flow. Here are the components with better explainations of their functions than provided in the .pdf document, ignoring pressure sensors.
3 - Hydraulic accumulator - stores pressurized fluid for immediate brake response from SBC system
y1 & y2 - Manual override valves - for when SBC system fails. Note that you only have front brakes when the SBC system fails.
7 & 8 - Pressure isolators for use with manual override y1 & y2 valves. These pistons keep high pressure fluid from backing up into the SBC system when in manual mode.
y6, y8, y10 & y12 - proportional sequence/reducing pressure control valves. These are the actual valves that make the SBC system work; i.e. - your "brake-by-wire" valves.
y7, y9, y11 & y13 - pressure release valves for relieving pressure from the brake calipers when you take your foot off the brake pedal.
y3 & y4 - Pressure balance valves. These insure that the pressure on the left & right brakes are equal on each axle at the appropriate time.
m1 - The SBC pump that provides all of the braking pressure during normal operation.
Important items of note.
1 - For those that want to argue symantics; Pumps provide flow, not pressure. Pressure is caused by a resistance to flow. I use the word pressure interchangably with with flow to simplify the concepts for those non-hydraulically experienced.
2 - When the car in not in operation, all valves are normally open, with the exception of the proportional sequence/reducing valves, y6, y8, y10 & y12, which are closed off.
3 - Presumably, the accumulator (3) has pressure stored between it and the sequence valves when the car is turned off. This pressure is about 2300 PSI.
4 - Return line to master cylinder reservoir comes in the top of the reservoir. Normally, a hydraulic return line returns UNDER the fluid level to insure no air is introduced into the system. I cannot determine by casual observation if the reservoir is actually made in such a way that the return does extend below the fluid level internally. This is important to note if using something akin to a Motive pressure bleeder for flushing brakes. Logic wants me to believe that this return does indeed return under the fluid level, although I cannot make this assumption.
5 - Not shown on the schematic are the bleeder valves on the brake calipers. When I refer to bleeding the brakes herein, the fluid will flow out of this valve from the caliper, although this is not shown in the schematic.
6 - There is no check valve shown on the outlet of the pump before the accumulator. I must assume it actually exists, else all accumulator pressure wold flow back through the pump into the master cylinder reservoir when the pump is shut off.
There are a number of difficulties that I can envision when trying to bleed the brakes using a Motive type bleeder on a SBC system. I first must assume that the car is off and nothing is being done to make the SBC system work. The Motive bleeder will have 20 PSI on it or so.
If there is stored pressure on the accumulator and a check valve on the outlet of the pump, it should be noted that the Motive bleeder will have no effect on the portion of the system between the pump outlet and the sequence valves. This part of the system would be held at 2300 PSI and obviously, a 20 PSI supply will not overcome this high pressure. Therefore, the fluid in the accumulator and its associated lines will not be exchanged.
Note that the back brakes on a SBC system are powered only through the SBC system, as there is no manual override. Since the SBC is presumably held at high pressure, the only bleed path for the rear brakes would be through the return lines via valves y11 & y13. If the retun line does not return under the fluid level in the reservoir, it will requre that air enter the return line until the fluid pushes up to the top of the return chamber and allows clean fluid to enter. So a big air bubble would be pushed through the system and eventually be bled out through one of the rear calipers. If this is true, a rear caliper should DEFINITELY be flushed out first so that extra air is not introduced into the front brakes' isolation piston assemblies.
The front brakes have two flow paths from the reservoir. One is via the return line and valves y7 & y9; the other is through the manual override valves, y1 & y2. However, the valves y7 & y9 lead to a dead end path on the backside of the isolation pistions.Therefore, when we get clear fluid from bleeding the front brakes, we know that we have bled the system via valves y1 & y2. This is a different path than followed by the flushing of the back brakes.
THE BAD NEWS:
There seems to be a good number of paths that are not exchanged in the flushing process when done manually in one's home garage. The areas associated with the non-spring side of the front brakes isolation pistons will not have fluid exchange, nor will the entire pressurized portion of the SBC system between the pump and the sequence valves. This means that you will leave a decent percentage of the old fluid in the system when performing a DIY brake flush with a Motive type bleeder at home. Once you start working the brakes in normal operation, this old fluid will mix with the new fluid. leaving considerable contamination in your brakes.
THE GOOD NEWS:
Examining line lengths, the storage size of the accumulator and possible non-exchanged fluid in the system, I would estimate that using a DIY method at home would exchange about 3/4 of the total brake fluid in a typical SBC brake system. If you let your brake fluid get really bad, this is not a good enough exchange. However, if you are flushing your brakes more often than Benz's recommendation using this DIY method, this percentage of exchange should keep your fluid in good condition. Again, this assumes you don't live in a tropical rain forest.
MY INTENTION:
Assuming my SBC system analysis above is correct, I intend to flush my brakes with a Motive bleeder once a year. This should give me a high enough exchange of the fluid to insure I have good fluid in my SBC system and keep the brakes in good working order for years to come. The complete brake flush at Benz which uses the SBC system and the Star Diagnostics costs $200 after tax. I would like to avoid this expense and inconvenience of yet another "dealer only" piece if maintenance.
If someone here has a more thorough understanding of the SBC hydraulic circuitry and can point out something I missed, PLEASE let me know.
PULLING ROTORS
I saw a couple of discussions on pulling rotors using prying methods and involvelemt with smacking with hammers. While this could be done, it's not so good on hubs and components in general. I would suggest using a puller. The method involves grabbing the outside edges of the brake rotor with the puller and then putting it under some tension. Using a pentrating spray lubricant at the junction of the hub and rotor is indeed a good idea. Then take a brass hammer and tap the center portion of the rotor in various directions. A rotor will usually pop free after just a few raps. More agressive methods risk damage to wheel bearings.
As you may or may not know, the brakes in your W211 have some very significant differences from those in the W210, as I have neither examined nor considered the differences between the two schema I can't comment whether your concerns re: flushing would be applicable to the W210. That part of your post is probably a better topic to simply start as a new thread either in the tech forum (wheels/tires/brakes) or the W211 forum. In any event, the PDF document is concerned ONLY with brake replacement and neither raised nor discussed flushing. Flushing was (in my mind at least) a previous hijack point or side-track in the thread. Since flushing remains off-topic to this DIY thread, I'm not going to comment on it further and I hope you can appreciate that. Since the stated main purpose of your post was to discuss flushing, please simply start a separate thread rather than expanding this one.
As you note, pulling rotors if done incorrectly can damage lots of other components, which is the greatest reason I have avoided most discussion of the topic. The rocking/wrenching process I described above has, to my knowledge, never damaged a wheel bearing, it's nothing like the shock that can be imparted by a large hammer hit (which itself has a greater possible immediate danger of shrapnel). Again, however, if you plan on re-using the rotor then a puller would be the best option, even the wrench process can damage the rotor.
explanation of the sbc system and probably a very good reason that mercedes is phasing out parts if not all of it
you need special computers/tools to shut it down or the pressures can blow you upand it counts brake applications so you need to go to the dealer to get it reset even if the brakes are not worn out(cha ching)Get a new benz and the dealer is going to get you
now aren't we all happy to have W210's
Flushing Notes & Other Observations 
and it counts brake applications so you need to go to the dealer to get it reset even if the brakes are not worn out(cha ching)Get a new benz and the dealer is going to get you
Linear Mode
