N_Jay

I think I let a little air in when bleeding the brakes when I changes front rotors and pads a while back.

So, I figured I would rebleed the brakes.
Only did the front, and used the power bleeder.
Set the pressure at 12PSI and opened the bleeder screw, and while it was bleeding cycled the brake peddle a couple of times. (Figured maybe the air was trapped in the hamster cylinder).

Did both fronts twice, ran through about 1/2 liter of fluid, no noticeable bubbles in the fluid bleeding out, but the brakes still feel a little soft.

It has been long enough that I might have forgotten how the felt originally.
I also changed to Centric Ceramic Posi-Quiet pads when I know don't have the best grab.

Thoughts?

Do you need to use a service tool to cycle the ABS on these cars?

2010GL550

All the GL's have weak brakes. If you just changed pads/rotors they might not have had enough time/mileage to fully "bed in" yet. Usually takes ~500 miles.


Every magazine/web review of the vehicle mentioned the soft brake pedal feel. I also believe Consumer Reports rated the brakes as a problem area.

2010GL550

2013 GL review, "What those braking numbers don’t tell you is that the GL’s mushy brake pedal meant that drivers sometimes misjudged the vehicle’s decelerative performance and found, halfway through a stop, that they needed to add more braking force in a hurry."


2012 GL post, "my brake pedal has to much travel before the brakes engage. the pads up front are new it has new fluid in the system i took it to Sun motors the Mercedes dealer in our area and the service writer told me that was the way that cars brakes are."


Etc, etc

N_Jay

The pads have over 3K miles.
"I have an appointment to have some front end wheel bearing noise checked out.
I'll see what my service guy says. (His wife has a similar year ML)

alx

You need to bleed more. Knock on the calipers with a suitable tool (handle of big screwdriver) and air will come out. There is a lot of fluid in the x164 brake system. If fluid is new and tour catch container is very clean you can reuse the fluid to minimize the amount used and prolong the bleeding.

N_Jay

I'll give that a try next time. Not sure I will reuse fluid. AT $12 a liter, it is probably not worth it. (Besides I figure a good bleeding is just part of "Changing the fluid")

alx

You are missing the scale of the project You might need to bleed for 15 minutes at a time... The front calipers can be very stubborn and hold air for a while...

N_Jay

I have never had to bleed brakes that long (Even with an open system).
I would think that it would be best to just bleed them a few times driving a week of so in between.

Driving to the shop today they "felt" better.
I think 1/2 the problem is the "other car" is a w211 with very firm brakes.

Maybe the "Power Bleeder" people need to make a recirculating system. Hook it up to all four bleeders and the master cylinder and turn on a pump.

alx

ah yes- if you have the time - this is the best approach.