primbesy

So I’m hitting almost 60K miles on my 2015 X166 and the brake sensor light came on. Will DYI replace brake pads, rotors, fluid flush. While I’m in that vicinity with wheels clearly out of the way, are there things I should also consider look for or doing preventative maintenance on/replace?

Any and all insights are much appreciated in advance!

BlownV8

I would just pop in new pads and be on your way. Easy driveway DIY. Changing the fluid is a good idea but make sure you use the right brake bleeder that provides positive pressure on the brake fluid reservoir. Also, make sure you follow the process to release the emergency brake before attempting to change your pads. The search feature is your friend.

chassis

+1

While you're in there give a good look around with a bright flashlight and inspect everything in your view. CV boots, ball joint and tie rod boots, cable and hose connections, axle oil leaks, etc.

silvergl

The first time I did the brakes I did not realize the electric parking system. After that super easy.

Akebonos are the best, super clean.

mtm

Be prepared for the rotors to not want to come off. Use a heavy hammer and a lot of patience, or a long bolt that could go through the eye of the caliper mounting bracket and two nuts to push the rotor off. When putting new rotors on, put some coper grease between the hub and the rotor, so it comes off easy next time.

chassis

A dead blow hammer is the tool of choice to remove the rotor, after first thoroughly wire brushing the hub to remove the rust crust as much as possible. A film of grease on the hub pilot is good practice when replacing the rotor.

oldmangrimes

First, nobody is going to find this thread in the future unless they search for "break" job, ha ha. Also, one problem I had was that when I was pounding on the passenger rear rotor, it jarred the connector to the parking brake position sensor slightly loose, so I got an vague error on the dash for "conditions not met" when I tried to return the parking brakes to regular position. Eventually I found the problem, even though the connector looked okay it wasn't properly mated. I was able to push on it, and once the connector was properly tight and "clicked", the error went away.
There is only one rear brake pad sensor, on the passenger side, so make sure you use the inner and outer pads correctly. There are two pads with notches for the sensor (one notch isn't used) and two without. I wasn't paying attention the first time I replaced the pads, and did the drivers side first, and put both pads on the drivers side with the notches. Then I got over to the passenger side, unwrapped the other two pads, and realized they both didn't have notches and I had to go take one of them off the drivers side. I was used to my other older cars that don't have brake pad wear sensors. Anyway, a silly mistake.
Finally, when my brake sensor light came on, the rear pads actually had a decent amount of thickness left. I knew it was the rears even though the warning light doesn't specify, as I had paid for the fronts to be done recently. When I pulled the rear brakes apart, the pad with the sensor had enough life to go a few thousand more miles.

primbesy

All - need help please.

Changed the rotors, brake pads and flushed the brake fluid per instruction using the bleeder pressure tank by Motive. My brakes are falling through and are half effective. Assuming I have some air in the system, did the bleeding procedure twice with to impact - same problem. What am I doing wrong? The only thing that didn’t go as smooth during the job was one of my front brake pistons fell out when I tried pressing the other side pistons back into place. Put it back into place and that was it.

Any guidance or thoughts what’s causing the issues?

chassis

You have alot of air in the system. The piston falling out is the likely cause.

Bleed over and over again until the system is free of air. It may take a while.

Please describe your bleeding procedure.

primbesy

So, I pressurize the brake fluid tank to 2psi and bleed each caliper for about 1-1.5 minutes each. Start with RR, RL, FR and finish FL. Re-pump the pressure after every wheel. Also, tried pumping the breaks while bleeding 10x during each wheel bleed. At the end release the tank pressure and normalize the fluid tank level. Tried all this 3 times so far. Can feel the pedal getting slightly better, but nowhere close to normal.

threeMBs

I know that Motive power (European 0100) bleeder must be pressurized to 15PSI (and should be maintained close to it throughout the procedure). How many 1lt bottles of fluid did you pour into it?

primbesy

I may be off on my labels, but I actually bring the pressure up to 28psi (sorry about the mislabel) and don’t let it drop below 15psi during the procedure.

Initially, I started with four 1liter bottles of Pentosin Super Dot 4 and now have 1 liter left with the rest in the system or drained (guessing about 1.5-2 liters in the system.

threeMBs

I would take it to a dealer and would ask for thorough flush. It is only about $125+/- labor cost plus cost of fluid (you've already saved a lot of money by changing brakes/rotors yourself). I would not mention to them your current situation. Let them do it right with their equipment. If pedal is still spongy, let them diagnose. They may have a good incentive of doing a thorough job since spongy pedal started after they did flush, right? (Do not worry, they will no go poor.)

primbesy

My biggest issue with taking it to a dealer is the closest one about 65 miles away and that’s a very small one with questionable service history. They were going to charge me 8 hours of diagnostic time to figure out that my auxiliary battery went bad and the 360 camera was deactivated in the settings. Spent $55 on the battery and turned on the camera in the settings.

This is a different situation I understand and I may not have a choice but to take it to a ‘real’ dealer about 125 miles away. I did another flush today and see improvement for sure. Maybe a couple more flushes is worth it before the trip. Learned my lesson with not changing pads on two sides simultaneously.

threeMBs

Maybe a second person slowly pumping brake pedal while you Motive flush it one more time will yield final results.

Not exactly sure what you mean.

primbesy

so while replacing pads on the front I took calipers and pads off of the rotors at the same time. While compressing the pistons on the front right side, I created pressure which pushed out the left piston out of the caliper and flooded it with air and fluid.

chassis

You need to keep flushing. That’s what the dealer will do.

BlownV8

Yeah, I do one rotor at a time and have never had an issue. Just did my right rear pads for the upteenth million time.

chassis

@primbesy What is your bleeding/flushing procedure? Please describe it in detail, leave nothing out.

arsupisemnet

He is using pressurized tank attached to brake fluid reservoir.
You right - regular two people pedal flushing will help him to purge air from system.

chassis

@primbesy which circuit are you starting with, what is the subsequent sequence, and how many circuits do you have open at one time?

primbesy

So I’ve been doing one nipple at a time following the recommended sequence - RR, RL, FR, FL at least 1-2 minutes each with break pedal pumping (30 seconds each) while pressurizing at 25-30 psi after each caliper,

chassis

Good, that is the correct sequence. How many bottles of brake fluid have you used so far?

primbesy

2L of pentosin so far.

Tiffany's GL450

I haven't changed the brakes on the wife's car (yet) but I figure its coming. I was going to change the fluid as done on the 'B' check in the next couple of weeks.
Why can't I just open the bleeder port on each brake, one at a time of course, and flush the fluid? This is our first Mercedes but it's not my first brake job. What makes this pressurized brake bleeder so special?

Chad