sgjii

I thought I would share my experience with caliper problems, replacement and bleeding issues. I hope this helps someone else on their brake replacement repair journey for their W212 E550.

I have a 2010 E550 4-Matic sedan (212.090). I replaced all 4 rotors and pads about 10K miles ago and used Power Stop brand. (Side Note on Power Stop-They have been OK on other makes, but after getting them this time, I would likely not choose them again for Mercedes based on fit/finish of parts received). Aside from low pads, my initial symptom was a bad pulsation in the front, felt through the steering wheel during braking. The Power Stop replacements only solved the issue for a short time and the pulsation was back. I delved into the problem further and found un-even pad wear but could not find run out in the rotors. Looking at the pad retaining pins, calipers and general condition of things, all were pretty crusty. I live in the "Salt Belt" here in Ohio and the car definitely sees winter. I decided to re-do the front brakes with better rotors, pads, calipers and caliper flex lines.

My first problem was finding calipers. My car utilizes the Brembo made 4 piston calipers. Lots of regular calipers for the W212, both new and reman, but the Brembo units were much harder to scare up. I ultimately found them on Rockauto for an amazing price of only $62/each for remans. The surprise was the $150/each core charge but at least I get that back. I went with the Centric brand product, I have used their products for my euro cars for more than a decade, with great quality and success. Cardone was not offered and FVP seems a little too new and unproven for me. I ordered up Centric reman calipers, Centric GCX Elemental Protection rotors, Centric front brake hoses and Bosch Quiet Cast ceramic pads.

The removal highlighted my problems, the pads were stuck in the calipers, rusted to the sliding surfaces and the pins were badly rusted. I think this was a combination of crusty calipers and perhaps prematurely rusting pad backing plates & hardware (quality issue with Power Stop? maybe). Pads that won't move properly would indeed create uneven wear and pulsation.

The parts went together like butter. I used the Permatex purple/ceramic based brake lubricant on guide pins, mating surfaces between pads and caliper and pad backing plates where the pistons meet up. I power wire brushed the hub faces and used aniti-sieze to coat them lightly. I was very pleased with the ease of install.

Bleeding the system was a whole different story. I use a Motive products pressure bleeder. I flush my brake fluid every two years or before HPDE tack events, if that particular car is headed to the track. Highly recommend their product for easy one man bleeding. I bleed right rear to left front / farthest to closest to master cylinder. Tapped the new calipers with a rubber hammer during bleeding to help with any trapped air bubbles. The peddle just would not firm up and feel good. I then looked in my X431 scantool for ABS bleeding but the W212 didn't show an option, even though other MB products were listed. I then searched the forums and found reference to needing to bleed the system with 2bar/29PSI of pressure. I have never bled brakes that high before but the Motive was able to get pumped up to that pressure. I bled the system 2 more times under high pressure but no change. Then I found a post suggesting that the car should be running, bleeder pressure at 29PSI and pump the pedal 10 times once the bleeder was opened on each caliper. Sounded like a little much but I tried anyhow, two cycles. NO CHANGE, Spongy brake pedal with too much travel. By this time, I had a gallon of fluid bled through.

I decided to test drive the car, see if there was a enough pedal to stop the car and bed the pads in. (Another side note - Power Stop's brake pad bedding procedure is by far the best spelled out I have seen and it does a great job across all brands for that initial pad to rotor seating.) I took my usual paved country road loop for brake testing and pad bedding. I could definitely stop the car and got the pads bedded, then cooled down with another 8mile long, slower speed loop. The brake pedal was still low, with lots of travel and spongy. I decided to try the "Ford Explorer poor man's ABS bleed" procedure to see if cycling the ABS pump would help. I jammed the brakes and activated ABS. Sure enough, after that hard stop and activating the ABS the pedal was good and firm, up where it should be and has felt normal and correctly functioning for the last 100 miles.

In retrospect, I think the high pressure bleeding, motor running, pumping the brake pedal during bleeding, etc. were all an exercise in futility, tantamount to legend or anecdote. I think the true answer is the ABS pump just needs to run after the system has been opened and bled.

Final conclusion: If your scantool will run the ABS pump then great! If not, try the poor man's method and get that ABS pump to run in order to complete the job.

juanmor40

To complement your experience to other's experiences as well.

https://mbworld.org/forums/e-class-w...ml#post8332876

cool breeze

Nice write up. I plan to go over the fronts on my new to me e550.
I really wish someone offered a non perforated disc for these as it seems warping is common and doesn't need to be on a street car.

S-Prihadi

If caliper is Brembo, you can buy the genuine service kit based simply on piston diameter from Brembo, or Nissan...yep NISSAN if your Brembo pistons sizes the same as mine
The only seal ( o-ring ) you can not but is the unique cross-over seal which are small ones handling fluid transfer between 1/2 side of the caliper.

Read here : https://mbworld.org/forums/e-class-w...-get-them.html
https://mbworld.org/forums/e-class-w...-overhaul.html