Brake Problem

[whitefestiva]

Hi, I've been trying to figure out whats wrong with my brakes. I'm pretty sure only the front brakes work. I just know a few facts:

- When stepping on the brake pedal (car off) its hard and solid
- When stepping on the brake pedal (car on) its like theres no brakes at all
- For the car to brake, you'd have to step on the pedal close to the floor

I tried letting all the air out of the brake lines but that didn't seem to work. Any help or tips would be appreciated! Thanks in advance

[relentless]

adjust the rears maybe.

[mattswabb]

How are you letting the air out? Are you bleeding them properly?

[mechanicaldj]

most likely it is a bad master cylinder

and what procedure are you using to bleed the brakes?

[getnhi1]

Yea, for one you need a new MC, you also need to check the wheels for leaking cylinders and such.
Your booster may be bad, it should hold some vacuum for while, after you drive it go back after 30 mins or so and try the brakes engine off, you should have some boost left, it shouldn't be rock hard on the first try, if it isn't pump the pedal until it gets hard, (don't even go there :lol then hold your foot on the pedal and crank it, you should feel it drop instantly.

[whitefestiva]

Hi, thanks for the replies.

Bleeding Procedures:
- used a clear hose to look for air bubbles
- used a clear bottle, filled with some fluid so tip of the hose submerges
- Bleed the MC first, followed by the wheels
- my son pumps and releases brake pedal slowly while i observe
- after no air bubbles are seen, we give it a few more pumps and move on to the next wheel

I followed the procedures exactly in a car repair manual for the 86 Toyota Corolla. Hope that's not the case!

* no leaks on at wheels or the MC

The MC is new because the old one was leaking fluid. Could it be that the MC was installed incorrectly? Anything I should check for in my current state to determine if its really the MC? I'll try to get my son to take a picture. Thanks again everyone

[relentless]

Did you bench bleed the new m/c. I have found that sometimes the car cant put full travel to the M/C piston (there is a reason for this). I would bench bleed the m/c with clear tubes in the fluid of the reservoir and push the piston all the way to end of travel. Put it on the car as in as short a time as it takes. Than bleed the brakes again furthest line to shortest. after that I do a couple of trips around the car bleeding to get as much fluid out for new fluid. I do this to get moisture which brake fluid will absorb of time out which is why you should use new fluid. Than check the rear drum adjustment because the further the brakes have to travel the more pedal it takes.

Since you installed a new m/c the rod that pushes it should be adjustable. You may need to readjust it. If you screw it out to far it will apply pressure causing the brakes to drag. to short means you have to apply more pedal.

[whitefestiva]

Hi, I'm new to fixing cars so is it possible to help me with this bench bleeding procedure? I'm actually helping my dad with this.. then i have to translate all this to him. I won't be home where the festiva is until a few weeks later, but I'll definitely pay close attention to this forum. If you prefer me to contact you via email, please PM me Thanks for everyones help

[mattswabb]

Here's how I do it:
Bench bleed the m/c. Install the m/c, do not hook up the brake lines. Hook up the plastic fittings that come with the m/c. Run the 2 clear hoses into the m/c reservoir so they will be under the fluid level. Fill the reservoir. Pump the brakes till no bubbles are present in the clear tubes. This may take a bit of pumping. Connect the lines.

At this point I usually go around and crack open all 4 brake bleeders and let the system gravity bleed closing off each one when they get a nice steady drip. Keep the reservoir full.

Then start at the right rear wheel and bleed. Pump up the brakes, hold and open the bleeder, close the bleeder then release the pedal. Repeat many times and keep the reservoir filled. Then go to the left rear, then right front, then left front. Usually 2 times around the car and they will be good.