Yesterday, I replaced the brake pads on our E500. I purchased the Akebono Euro pads, so that I could eliminate some brake dust. I found that the current pads were Jurids. I am glad that I decided to replace them, because I found that the sensor on the left side was removed, and the wires were wire nutted together. There were not any brake warnings due to the wire nutted sensor wires, so I guess that the wire nut had the system fooled into thinking that all was OK. The Jurid pads did not have very much wear on them, and the rotors were fine. Our car has 42,000 miles on it, so these pads were probably installed fairly recently. I also cleaned and applied Meguiars NXT 2.0 to the previously nasty interior of the wheels.

The first step I took was to unplug the SBC connector, then removed both front wheels. Before I pushed the pistons back into the calipers on the fronts, I removed the old fluid from the master cylinder, and replaced it with new Mercedes fluid. I then used a Mityvac on the front calipers until I got clean new fluid from them. I then pushed the pistons back, and replaced the pads, and reassembled everything. I plugged the SBC connector back in and then started the car, pumped the brakes, and the warnings went away after two of these cycles. All OK so far, so I went for a drive, and the new pads were much more responsive than the previous Jurid units.

I then removed the rear wheels, and made the mistake of trying to use the Mityvac on the left rear caliper bleed screw. No matter what I tried, teflon tape on the bleed screw threads, silicone vacuum grease around the caliper & bleed screw, etc., air would still pull out with the brake fluid. I just cracked the bleed screw on the right side, and pushed the caliper piston back, then closed the bleed screw.

After reassembling the rear units, plugging in the SBC unit, and starting the car, I am getting the same message - "Reduced Braking Power, Visit Workshop". The only difference is that it is not going away, even after five or so brake pumping & starting cycles. I am sure that this is the result of air in the left rear caliper.

I have ordered the Motive Products Euro Power Brake Bleeder, and will try to expel the air when the unit arrives. I really hope that there is no damage done, but feel that the problem is just air, and the SBC unit is sensing that there is not enough pressure building from the rear. When I recieve the Motive unit, I will repost how this turns out.

Moral of the story - do not use a Mityvac to pull fluid from Mercedes calpiers, but do use a Power Bleeder to push it through them.

If you guys can offer any advice, then I would be more than appreciative.

 

In the past I think that I have been able to bleed the air out of brakes by simply letting it leak out. ie cracking the bleeder and using the head of the fluid in the master cylinder to push air. Just a thought for something to try while you are waiting for your power bleeder. Which reminds me I have one which I need to get back from a guy from work

 

Thank you for the suggestion. I have used that method on other older cars before, and was successful, but no fluid leaks out of these bleeder valves by just loosening them. I noticed this when I first started the bleeding process. When the bleeder valve was loosened for the other side was loosened, no fluid came out until I compressed the caliper piston.

I thought about loosening the bleeder valve, connecting a hose to the valve, and placing the end in a container, then reconnect the SBC connector, and unlock the door. The self test of the SBC pump should pressurize the circuit, and purge the air.

At this point I do not know what damage could be done by using this method, so I think that I will just wait on the Motive pressure bleeder.

 

My guess is you pulled air through the threads on the bleeder screw as it was not a leak proof seal after you opened the bleeder

 

Problem Resolved! The Motive Power bleeder arrived today, and in no time, I had the brakes bled. My original problem was due to draining the master cylinder reservoir dry on the back side. The fluid never appeared to be less than the minimum mark, but it was in fact dry on the back side.

After purging the air from the lines, and starting the car, the rear pads pushed out to the rotors. No more warnings, alarm tones, or messages. I drove the car about 15 miles, and the brake response is far better than it was before the pad and fluid exchange.

I feel truly lucky today!