Brake issues?

[eclipsed123]

I having issues getting a firm feel from my brake pedal. I've bled the system multiple times and the pedal is still spongy. If I bleed the system with the car off the pedal is firm but as soon as I start the car the pedal goes soft again. I bled them in the following order RR, LF, RL, RF having my fiance pump the brakes a couple of times then hold while I lloosened the bleeder repeating on each caliper. I am getting a good stream through each caliper but the pedal has to be pressed pretty hard to the floor to come to a stop. Also my anti-lock light is on the car is a 95 gsx with abs. I wonder if the master cylinder or brake booster could be bad? Any help or advice would be appreciated.

 

[Soccerguy136]

First off you are bleeding in the wrong order. It always goes farthest from master cylinder to closest.

The order would be Passenger Rear, Driver Rear, Passenger Front, Driver Front.

The abs light on either means there is a leak, unplugged sensor, or low fluid.

IMO, when you are bleeding the brakes at first, put a brick or something underneath the brake pedal. Too much pumping and pushing completely down can cause the master cylinder to lock up.

The procedure I follow is to bleed each wheel 10 times, with 10 pumps per time. As in, have the person in the car pump the pedal 10 times and hold while you bleed. Close the screw and repeat 9 more times. Do this for all 4 wheels in the order specified above. Then go back and do it again without the brick. It should only take about 3 times per wheel with no brick. The pedal should be rock solid by now.

If it's not you have other problems.

You said fluid was squirting out on all calipers so it doesn't sound like a bad master. The brake booster only assists when the car is turned on and works off vacuum. It has nothing to do with pedal feel while the car is off. Since you said your pedal is having problems once you start, you may have a bad/leaking booster or backwards check valve.

Check your brake hoses and lines for leaks. While you are bleeding look for any fluid dripping on the ground. If you have no bubbles in the piece of tubing you are using to bleed the brakes then it is unlikely you have any leaks.

Are the calipers clamping down when the person is pushing down on the pedal. You should see the calipers moving/wiggling and clamping on the rotor. Try turning the rotor when they have pushed on the brakes. If you can turn the rotor, the caliper is bad.

Hope this helps.

Keep us posted on progress.

 

[SICK SOCIETY DSM90]

I totally agree with the information about bleeding the brakes in that order to get best results. Only thing I did not see on the post make sure your brake fluid level is totally full before you start your bleeding and add if you need to so your master cylinder does not run dry and put a bunch of air in your system. also take a look at them brake pads and calipers if there is not enough brake material it will cause the caliper cup to over extend and will not put the pressure you need on caliper. One other bit of info we do at our shop is before you start the car after replacing brake pads and depressing the calipers you have to pump the brake a bunch to get pressure then bleed and you should have no problems as long as there is no leaks or air in the system.

 

[truesk83r]

I had a problem with my master cylinder not holding the pressure to the lines. a new one fixed my problem

 

[TSiAWD666]

First off you are bleeding in the wrong order. It always goes farthest from master cylinder to closest.

The order would be Passenger Rear, Driver Rear, Passenger Front, Driver Front.

Actually he is bleeding them in the correct order. The reason is that we use a diagonally split braking system where RR and LF are connected to one channel, and LR RF are on the other. Design is for safey so that if you lose one channel you still have one front and rear as well as one left and one right available in the other channel.

 

[eclipsed123]

Ok I changed out the master cylinder with a known working one and still the same spoongy pedal. I then took the hose off that goes from the brake booster to the intake manifold. It didn't appear to be cracked anywhere so I put it back on the opposite way it came off. The brake pedal became really firm I thought that solved my problem but when I went to drive it I had a firm pedal but the car wouldn't stop. There was a little valve inside the hose I assume that is the check valve that was mentioned. I'm going to swap the hose back around to where is originally was but that still leaves me with spoongy brakes. Is there anyway to test the brake booster to see if it is defective? I don't see any visible leaks anywhere and I'm not loosing brake fluid from the resevoir. I'm kinda stumped I've already went through 2 bottles of brake fluid bleeding the brakes.

 

[eclipsed123]

I'm having a very difficult time removing the brake booster. I have the master cylinder and resevoir removed. I've disconnected the brake pedal and removed the 4 nuts from under the dash but I can't seem to wiggle the booster itself out. There just doesn't seem to be enough clearance to remove it.

 

[3kgt2nv]

if swapping masters make sure you have adjusted the actuation rod to correctly engage the piston