The other day the brake pressure on my car went down significantly. Yesterday, it went almost completely away. This is really worrying me now, since I can't find what's wrong. I've already checked the fluid and the pads, and they both look good. In order to stop, I have to push the pedal to within maybe a 1/2" of the floor. This is not fun when driving in a city for most of the drive... Please help... I'm completely out of ideas...

 

if your fluid and pads are good, then you have an air bubbles in your system. You need to bleed your brakes.

 

Check the master cylinder for leaks while you're at it too.

 

I did look under the hood today while I was at school, and everything underhood looked good and dry. i didn't feel around on anything because it was raining, and i was running a little late for a meeting. Looks like this weekend should be pretty nice, so I'll for sure tear into everything then. I just hope I'm still alive at that point...

 

check fluid. fill wait. and check the next day how much you are leaking. It could be anything a bad line, cylinder. etc

Good luck

 

It's not leaking at all... That's the thing... I'm hoping it's just air in the lines. That's a pretty easy fix, just need some time to do it. The fluid level in the reservoir is like dead on the "top" line. It's been there for the last couple weeks, since I last checked it...

 

same thing happened to my bro's accord that I just worked on. after bleeding it twice n still no pressure, I figured out it was a dead master cylinder. same exact symptoms as u.

 

same thing happened to me twice, both time one of my rear calipers started leaking, had to replace both of them at seperate times

 

If I had air in the lines, wouldn't pumping the brakes bring the pressure back up? That was my first thought, and when I pumped the brakes, it got a little bit more pressure but not nearly as much as it should have... Also, does anyone have pics of where the master cylinder is in the engine bay for an F23? I looked yesterday for any leaks or anything underhood, but couldn't find anything, nor could I find the master cylinder. I'm going to try pumping the brakes today at lunch with the car off, and see if that will build pressure. If not, I'll definitely be looking for pics/diy/how to on replacing the master cylinder.

 

My money is on this if his fluid leveling isn't changing.


I had the ole leaky rear calipers situation before but that one is obvious.

 

before jumping to conclusions you have to rule some things out, the easiest less expensive route is bleeding your brakes. Try that first, then you can cross that off and move on to your caliper check since you have the rims off.



happen to me as well, both my front calipers failed!

 

What am I looking for when I check the calipers? Leaks, broken ish, what?

 

look for fluids, brake fluid to be exact, any leaks around where the calipers meet the lines, etc

 

the lines going to it, and the caliper its self. the piston has a rubber seal around it, make sure its not torn.

 

But wouldn't any/all of those things cause the system to lose fluid?

 

yes slowly. But thats what happen to me. fluid looked fine but no brake pressure due to it not pressing the piston right

 

Shit has officially hit the fan with this problem. On the way to work this morning, the brakes went completely out 3 times. I had to use the e-brake and engine brake in order to get stopped/slowed down. I had my foot to the floor, and I got nothing... It was awesome, let me tell you... So I checked the fluid level, and it's in the exact same spot it was yesterday, so I'm not losing fluid. Seems like it's the master cylinder. They're about $100 (conservative estimate) so I'm going to replace it tomorrow...


Has anyone replaced the master cylinder? If so, how hard was it? Any kind of DIY or anything like that for it?

 

Replacing Master Cylinder (MC) is easy. MC is the part underneath the reservoir. You may need a 10mm flare tubing wrench to loosen the brake lines to the MC. The tiny nuts are very tight and an open end 10mm may round them off. Two larger nuts (14mm?) retain MC to vacuum booster studs. Replace MC w/ OEM unit to insure same booster-MC gap is maintained. If you go afermarket you may need to adjust brake pedal linkage. Trust me you don't want to do that adjustment.

After replacing MC, bleed brake lines, RR, LR, RF, LF. I've never found that the sequence makes any difference, but the manual says to longest to shortest brake lines in that order.

you will need about a qt of brake fluid. Avoid spilling brake fluid on car painted surfaces, as it will damage paint.

In my experience ABS system will take care of itself, so nothing to do there.

good luck