Brakes not working right

Try bleed

1. Check the fluid level in the master cylinder. ...
2. Locate the bleed screw on the slave cylinder. ...
3. Attach the hose to the bleed screw. ...
4. Open the bleed screw on the slave cylinder. ...
5. Have a friend press the clutch pedal in and hold it. ...
6. Close the bleed screw. ...
7. Have your friend release the clutch pedal.

Bleeding Clutch by Blocking the Slave Cylinder

try to drive on gravel and hit brake hard to make sure the ABS pump run then try to bleed again

Bleed master cylinder ,with brake lines disconnected,then connect brake lines and bleed each brake line at master cylinder. then right rear brake,then left rear brake,then right front brake and last,left front brake.

Did air get into the master cylinder? If you can, try bleeding the master cylinder. The fact that you aren't getting any fluid out of the line suggests that the master cylinder isn't pumping fluid.

Master cylinders are (usually) on a split circuit system - that is, the front left brake is on the same line as the rear right. The front right brake is on the same circuit as the rear left.

A point to be aware of is when bleeding brakes/doing brake work and if the master cylinder runs dry, is that a seal inside the master cylinder can fail/twist over and not pressurise that particular line, even though it may pressurise the opposite brake line.

I'm in the UK. I have a 1998 Jeep Grand Cherokee 4 litre, which I am slowly rebuilding. Three weeks ago I fitted new front brake rotors, new front callipers and pads. I've been rebuilding cars for over 40 years now and have done countless brake overhauls.

.. and could I get a hard pedal after the job was completed? I must have bled the brakes three times a day for a week and couldn't get a brake pedal. I phoned a full time mechanic I know - he came and tried to bleed the brakes three times and couldn't get a hard pedal.

That's when you think 'The master cylinder was working before I started the job so it must be still working now'.

I fitted a brand new master cylinder and because some parts for older jeeps are hard to come by in the UK, I fitted a second hand proportioning valve. When I bled the brakes again the pedal became rock solid. Fixed.

You're probably fed up with your braking problem now ... and apparently this 'no fluid/brake pedal' is more common than you may think.

Try bleeding the master cylinder if you can. If you suspect that it isn't fully working - try an overhaul kit which is cheaper than a new master cylinder.

As for changing the proportioning valve .. that's your decision. My brakes now work though the truth is I don't actually know which was at fault as I changed both the master cylinder and proportioning valve at the same time. Maybe both were at fault, for whatever reason. I genuinely don't know.

The positive aspect is that you are doing your own work and know what you're doing. You're saving on labour charges.

you may have to run the motor as you bleed the brakes so the abs hydraulic unit can purge any air that might be caught within the unit itself.did you bench bleed the master cylinder before installing it on the car.this can save time and reduce the possible chance of air entering the system.make sure you don`t allow the master cylinder to run low on brake fluid.i also assume that you are bleeding the brakes properly.Left front brake works with Right rear brake and Right front brake works with Left rear brake.this is how the brakes should be bleed.

Is the master cylinder good? a bad master can cause this also did you bleed the master first before bleeding at the wheel and also make sure the bleeder screw is clean, if the hose is good then theres only a few things, a bad master or a master that wasnt bleed, try bleeding the master first then try rebleeding the brakes.

The brake system bleeding procedure differs for ABS and non-ABS vehicles. The following procedure pertains only to non-ABS vehicles. For details on bleeding ABS equipped vehicles, refer to the ABS procedures later in this section.

WARNING Make sure the master cylinder contains clean DOT 3 brake fluid at all times during the procedure.

1. The master cylinder must be bled first if it is suspected of containing air. Bleed the master cylinder as follows:
   1. Position a container under the master cylinder to catch the brake fluid.
   2. Loosen the left front brake line (front upper port) at the master cylinder and allow the fluid to flow from the front port.
   3. Connect the line and tighten to 24 ft. lbs. (32 Nm).
   4. Have an assistant depress the brake pedal slowly one time and hold it down, while you loosen the front line to expel air from the master cylinder. Tighten the line, then release the brake pedal. Repeat until all air is removed from the master cylinder.
   5. Tighten the brake line to 24 ft. lbs. (32 Nm) when finished.
   6. Repeat these steps for the right front brake line (rear upper port) at the master cylinder.
      

WARNING Do not allow brake fluid to spill on or come in contact with the vehicle' finish, as it will remove the paint. In case of a spill, immediately flush the area with water.

1. If a single line or fitting was the only hydraulic line disconnected, then only the caliper(s) or wheel cylinder(s) affected by that line must be bled. If the master cylinder required bleeding, then all calipers and wheel cylinders must be bled in the proper sequence:
   1. Right rear
   2. Left front
   3. Left rear
   4. Right front
2. Bleed the individual calipers or wheel cylinders as follows:
   1. Place a suitable wrench over the bleeder screw and attach a clear plastic hose over the screw end.
   2. Submerge the other end in a transparent container of brake fluid.
   3. Loosen the bleed screw, then have an assistant apply the brake pedal slowly and hold it down. Close the bleed screw, then release the brake pedal. Repeat the sequence until all air is expelled from the caliper or cylinder.
   4. When finished, tighten the bleed screw to 97 inch lbs. (11 Nm) for the front, or 66 inch lbs. (7.5 Nm) for the rear.
3. Check the pedal for a hard feeling with the engine not running. If the pedal is soft, repeat the bleeding procedure until a firm pedal is obtained.

Fig. 1: Loosen the front brake line in order to bleed the master cylinder

Fig. 2: Connect a bleed hose from the bleed valve on the front caliper to a jar of brake fluid

Fig. 3: Always follow the lettered sequence when bleeding the hydraulic brake system

Hope this helps to solve it; remember to rate this answer.

Start by bleeding master cylinder, will take two to do this, have some pump the brake paddle about ten time every time, have them pump it and hold it down while you open brake line when paddle goes to floor close and pump again ( one of the brake lines at the master cylinder ), keep doing that till no more air comes out, then do the other brake line at master cylinder again till no more air comes out, keep an eye on master cylinder that it don't go low on brake fluid or you will have to start all over again, how go to right rear wheel and bleed till no more air comes out ( have them pump brake paddle and hold while you open and close bleeder valve, do not let them release brake paddle till you have close bleeder valve, keep doing that till no more air comes out, then go to right rear, then left rear, from there right front and last left front.Hope this was very helpful, good luck.

The master cylinder supplies the pressure to the brake fluid that travels between the maste brake cylinder resevoir and the brake caliper pistons (through the brake lines. If the master cylinder fails there will be insufficient compression of the brake fluid to make the calipers operate as designed. Leaks in the brake lines and/or cylinders is a possibility, and unrelated to functionality of the master cylinder. Also, pistons located in the brake calipers can form a corrosion ring on their inside walls if there is breakdown in the brake fluid or moisture that gets into the lines. Operating the vehicle when there is insufficient brake fluid in the master cylinder resevoir can also lead to air getting into the brake lines, causing bad working brakes. Air compresses more than brake fluid, and the master cylinder isn't designed to compress air in the brake lines. Sounds like a bad case of "lack of maintenance", as opposed to bad advice from the mechanics. That said, there's no excuse for bad installation. But, it's tough to improperly install a brake line since they are nothing more than hollow metal tubes. There should be no rubber connectors installed in the brake lines. When bleeding the brake lines one must remove all of the trapped air before you will see any fluid appear. If the valves in the master cylinder are not properly operating the master cylinder will not allow the brake fluid to get into the brake lines.

Hope this helps.

did you bleed the master cylinder before you put it on the car .
New master need to be bench bleed before you install them then bleed all the brakes starting with the furthest one from the master