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I heard this horrible grinding sound, metal on metal, coming from the rear of the 15 ML350 with 50K miles on it. I told myself it couldn't be the brake pads worn out already, and anyway, MB has brake pad sensors, and I had no warnings. So I pulled the rear wheels and could immediately see a problem on the driver's side. The inside brake pad was gone, and of course the wear indicator is on the passenger side. Here are the size of the brake pads in MM:
I can replace the rotors and pads, but what about that uneven wear? Any idea of what might cause such uneven wear? I didn't buy the car new. I bought it a few years ago when it had 30K on it, private party. Besides changing the oil, and filters, this is the first work I have had to do on the car.
Here is a photo of the worn pads:
On the 2016+ W166 GLE a faulty parking brake actuator can cause uneven wear between inner and outer pads, but I'm not sure the ML has a similar setup. On the 2016+ there is a parking brake actuator on both sides. Both of mine worked fine (in terms of parking brake function) but one was not retracting properly or sticking, because it was wearing the inner pad a lot more than the outer on the driver side. Could be something to check? BTW mine had 60K miles when I noticed the problem (when pad was getting thin on one side), so similar mileage to yours.
Make sure slide pins are CLEAN and well lubricated with high temp grease that comes with your new pads...that is the most common cause of uneven wear...sticking calipers. Rear brakes on MLs wear fast. Mine is on 3rd set of rears with only 60k on clock and no active lanekeeping and dont use cruise (both use rear brakes).
Thanks. The 15 ML350 has the electric parking brake actuators on both sides too. I will look at these actuators as well as the calipers. Perhaps my situation is the same as yours? The parking brake works fine, but perhaps it is also not retracting properly, and causing the wear here too?
On yours, did you try cleaning/repairing the PB actuator? Or did you simply purchase a replacement?
Originally Posted by gearFX
On the 2016+ W166 GLE a faulty parking brake actuator can cause uneven wear between inner and outer pads, but I'm not sure the ML has a similar setup. On the 2016+ there is a parking brake actuator on both sides. Both of mine worked fine (in terms of parking brake function) but one was not retracting properly or sticking, because it was wearing the inner pad a lot more than the outer on the driver side. Could be something to check? BTW mine had 60K miles when I noticed the problem (when pad was getting thin on one side), so similar mileage to yours.
Thanks. I did check this as it is an easy thing. I found all the pins on both sides really moved well. As the brake on the passenger side is in good shape, 6mm and 8mm, I don't believe it is the pins. I am going to be more observant when doing the winter/summer tire change over. To try to catch problems like this before I have to change rotors and pads.
Originally Posted by Leetom
Make sure slide pins are CLEAN and well lubricated with high temp grease that comes with your new pads...that is the most common cause of uneven wear...sticking calipers. Rear brakes on MLs wear fast. Mine is on 3rd set of rears with only 60k on clock and no active lanekeeping and dont use cruise (both use rear brakes).
Thanks. The 15 ML350 has the electric parking brake actuators on both sides too. I will look at these actuators as well as the calipers. Perhaps my situation is the same as yours? The parking brake works fine, but perhaps it is also not retracting properly, and causing the wear here too?
On yours, did you try cleaning/repairing the PB actuator? Or did you simply purchase a replacement?
Did not attempt to rebuild/repair the actuator. It was a $332 part and only did one side (the inner/outer pads on the passenger side matched thickness).
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15 ML350 Uneven Rear Brake Pad Wear 50K
