Brakes (FL) Won't Bleed after Repair


I’ll ask a more specific question . . .

With the old master cylinder, did you have problems bleeding the right rear?

And what method did you use?

Yes… The right rear had the same symptoms as the front left. I was concentrating on the front which is why the “(FL)” is in the title. I believe the fluid flow is controlled/directed through the ABS module.


Thanks for that information

Now I see what was going on

It isn’t uncommon for an existing master cylinder to go haywire and need replacement due to a bleeding process. Think about what happens. All the time it has been in use the MC piston resided in a small portion of their available travel space inside the MC bore. Because it is locked there by the hydraulic pressure. But when you release the hydraulic pressure for a bleeding, the piston can then move freely in the bore. And when it does, it can encounter a burr in a portion of the bore it never traveled to before, which then damages the piston seal.

That’s why some of the experts here recommend to use a pressure bleeder procedure rather than rely on the common DIY method of pushing on the brake pedal while tightening/untightening the bleeder screws. I 'm just a DIY and don’t have a pressure bleeder myself, so the compromise technique I use is to push on the brake pedal with my hand only so I can limit the amount of travel I allow for the brake pedal. So far this has worked for me well on my Corolla, original brake MC for over 20 years.

Hi there,
i know its been 3 years since this post active, i am facing the same issue with my Lancer Evo3 (righth-handed car) for FRONT LEFT caliper that wont give pressure if my keys in IGN position. if the key some what at OFF/ACC/START position, i can feel the MC piston is freely travel while i am bleeding the brakes. i notice just now while i am doing full swing pressing the pedal while my keys at ACC, still holding the pedal until i switch my keys to IGN an then i release the pedal, then i try to press it again, an i felt so hard to press, the MC pistons wont travel! by the way, i am by passing the FORNT LEFT caliper while doing this, meaning my caliper was on the floor just finished inspection (I suspected my caliper had jammed but not!), but i rather want to test the FRONT LEFT pressure line itself, so i put a transparent hose to it and dump it to the brake reservoir tank on the other end, it should press freely right? due to no restriction of fluid flowing,right? but i then found the ABS is locking/restrict the flow of the brake fluid while my keys at IGN position. if I put my key at the other position, i can press the brake pedal freely again. I disconnect the ABS harness at the ABS controller for now so that my car can be drive-able. i would do more harness inspection for my ABS system then, because i had replaced all item below;
-Master Cylinder pump (OEM)
-brake pistons (i have 4 piston, 2left, 2 right)
-brake service kits (in my case, my service kits same with Mitsubishi pajeroV6/storm for front twinpot caliper)
-brake fluid flushed (dot4)
-brake bleeding all 4 FR/FL/RR/RL
-ABS pump/controller

Terengganu, Malaysia.