Cannot Retract Brake Caliper Piston
Discussion
It's time to replace all the discs and pads on my 2013 Mercedes A250 (W176). I've started at off-side rear and all was going well until it came to retract the brake caliper piston back in to fit the new pads. It just won't squeeze in, I've even tried loosening the bleed valve and unscrewing the brake reservoir cap. I tried so hard that my brake piston wind-back tool snapped *sigh*.
In addition, is the black plastic box at the back of the caliper the electric parking brake actuator? Haven't come across this before, probably because I tend to work on slightly older/less sophisticated cars.
In addition, is the black plastic box at the back of the caliper the electric parking brake actuator? Haven't come across this before, probably because I tend to work on slightly older/less sophisticated cars.
Edited by EViS on Sunday 18th August 15:45
Athlon said:
The park brake needs to be in service mode before you try anything.
Some are left handed thread to wind back..
Sometimes the piston does seize in the caliper. The brakes would continue to appear to "work" if the sliding mechanism can make the opposite pad do the work. Are the pads worn evenly?Some are left handed thread to wind back..
Although I'm not familiar with that particular model, I have done pads and discs on other (more mundane) cars and had to free off both the piston and the caliper sliding mechanism a few times.
M4cruiser said:
Sometimes the piston does seize in the caliper. The brakes would continue to appear to "work" if the sliding mechanism can make the opposite pad do the work. Are the pads worn evenly?
Although I'm not familiar with that particular model, I have done pads and discs on other (more mundane) cars and had to free off both the piston and the caliper sliding mechanism a few times.
I know, I fix them for a living! Rare for a Mercedes caliper to seize to be honest.Although I'm not familiar with that particular model, I have done pads and discs on other (more mundane) cars and had to free off both the piston and the caliper sliding mechanism a few times.
Bottom line is the guy is risking damaging things if he does not have the gear, you must have it in service mode before retracting the piston.
Thanks all . I feel like such a numpty! First car I've ever worked on with an electric brake and obviously didn't appreciate fully how they function! A quick search and I found how to get into the service menu to wind the electric brake back, smooth sailing from there!
Here's hoping I didn't damage anything with the excessive force I put into the wind-back tool . Took the car for a quick drive and engaged the parking brake a couple of times, all seems well atm.
Here's hoping I didn't damage anything with the excessive force I put into the wind-back tool . Took the car for a quick drive and engaged the parking brake a couple of times, all seems well atm.
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