Rear Brake Job Questions

[truekoa]

Hi all,

First time doing my rear brakes on my 2019 Expedition Max, I did look at several YouTube videos and posts on here but I feel I definitely did something wrong or missed a step bc my pistons right now seem like they are over extended and protrude mostly outside of the protective boot, almost like the piston is barely hanging on.

With some effort and a caliper piston tool, I can get the piston to seat back inside the boot but not flush enough to even reinstall the old brake pads, let alone the new ones. When I push up against the piston, the boot swells with brake fluid as if there is too much brake fluid pressure so I did undo the brake fluid cap while doing this but still, if I push on the piston too much, brake fluid will squirt out of the boot.

The vehicle is in parking brake maintenance mode as well.

What am I doing wrong? Thanks in advance.

 

[duneslider]

ANy pictures. The rear brakes were seriously some of the easiest brakes I have ever done. You are certain the brakes are put in the maintenance mode? I push my pistons back in with the pads still in the caliper with a flat bar, super easy to push in. Popped the new pads in and was done. There shouldn't be fluid in the boot...did you pump the brakes with no pads in or hit the parking brake button with the caliper off? It sounds like you have pushed the piston all the way out, which happens if you do the previous mentioned things, or pull the caliper off before putting it in maintenance mode. I am not 100% on how to push the piston back in but it might have to be turned as you push it in and all the fluid in the seal will make that difficult. Drain some fluid out as you push it in. You will probably need to bleed the brakes after this also. It might also be possible to take the motor off the back, not sure if that would help or not.

 

[truekoa]

So I think I did take the caliper off before putting the vehicle in brake maintenance mode. I just looked and one of the pistons is completely out of the boot now.

Any chance I can put it back in or do I have to purchase new calipers?

 

[Ellison Brown III]

Did you take the cover off the brake master cylinder reservoir? This will relieve the pressure your fighting against while attempting to push the pistons in the caliper/ prevent the fluid from rushing out.

Depending on how much fluid is in the system it could come out of the reservoir. However, due to the worn pads (level should return to approximately normal when new pads installed) the level should be low. Also, you mentioned some escaped from the pistons over-travel so it’s most likely low now; so, shouldn’t overflow from reservoir.

Also, this method relieves the system of air as all movement of pistons pushes bubbles up towards the open reservoir. After all work is completed firmly press the brake pedal 8-10 times. Should get firmer the more you press it. Once it’s hard to press at the end you’re good. Cap back on the reservoir and that’s it.

Proper bleeding will have you open the bleed screw at each caliper. This not only rids the system of air, but old/ dirty fluid at the caliper. Happy wrenching.

 

[ColoradoJon]

older thread but I was able to put the caliper on a jack stand with an old pad in between and push it back with the cap off the reservoir. I am a bit on the heavier side (250lbs) but just putting my weight on the back of the caliper while on my knees moved it back into the caliper. Maybe this will help somebody who didn't buy the fancy tool.