brake problems

I am having brake problems. I just changed a strut on the rear of my 91 corolla and i had to take the metal brake line from the back of the plate. I put it back on right but now I don't have brakes. I tried to bleed them but I can't build enough pressure. I pumped itup and it built pressure for a second and went back down. After that I couldn't get to that point without starting the car and shutting it off. Can the master cylinder pump brake fluid still if its no longer working properly? Answers are greatly appreciated.

Your car has a power boost sytem and the car must be runningif you are bleeding the system manually. It is a 2 person job. If you get a bleed kit from the auto store you can do it yourself.

A bleed kit costs around 15 bucks plus. It all depends on what type you get.

yes have it started with someone in the car have them pumprd up if you can but if it don't pump up have them to push them from the floor while you have bleeder open but don't let off until you get bleeder tight then try to pump them up the second time if you can and do the same pumpping until it wont pump up any more. then you should be getting fluid 2nd or 3rd time.

Whats the difference between bleeding them when the car is off and when the car is running?

because you have power brakes it booster and you need all get all the air out of it.also when you get all air out when pushing on brake pedal you should be able to put your foot under the pedal when all airs out.

You can bleed them manually. If you want to, give them a pop with the car running at the end. I usually reserve bleeding under power for pushing out the caliper pistons only.

Bleeding under power increases the chance of pushing the master cylinder piston past the ring of crud inside the bore and scoring up the master cylinder cups. Whoever you get to help, you have to tell them to go real easy when you bleed with the engine running, not to push it to the stop.

Bob

I can do it with the car started but how do you do this if you can't build any pressure with the car on? It goes to the floor. There is brakes but not nearly enough to stop the car in safe time. I have bled all four twice. Can the master cylinder pump fluid if its dead? How can you know if it isn't the brake booster thats dead?

yes he's right he exsplained to better than me..

I can do it with the car started but how do you do this if you can't build any pressure with the car on? It goes to the floor. There is brakes but not nearly enough to stop the car in safe time. I have bled all four twice. Can the master cylinder pump fluid if its dead? How can you know if it isn't the brake booster thats dead?

If by now you're this messed up with it, have it towed to a shop and get it fixed right. You should be able to build pressure with the car off, your brakes WILL work with the engine off. Look for a kinked line in the area where you worked on the struts. Are you losing fluid?

You may have pushed the master past the normal range of travel. When they get old, there is a ring of rust in the piston bore that comes from condensation on the bare cast iron surface. If you push the piston past it (which you did if it goes to the floor) the chances of scoring the cups is great. The leak might be external or internal (bypassing), take a look at the base of the master where it meets the power booster.

To rule out a bad power booster (probably not your problem), shut the engine off, pump the pedal until all the vacuum is out of it and the pedal is hard. With your foot on the pedal, start the engine. The pedal should sink a little, if it doesn't, either the booster or check valve might be bad.

So, check all your lines for leaks, eyeball the master, make sure all of your bleeders are closed. Start with the RR wheel, try and bleed it again. Have the pedal person apply light pressure but not down to the stop. If by 4-5 shots it still spits mostly air, I would suspect that the master is bad.

I trust that you know how to bleed brakes. You have to talk with the pedal pusher, tell him "up", "down", "hold it down" and "go easy". They have to answer you back. Sounds silly, but it works. Never ever have someone let up on the pedal when the bleeder is open, which makes the task infinitely worse.

If you decide to change the master, you have to "bench bleed" it first. I use this method: Lock it in a bench vise first. Fill the master, leave the top off. Take a big screwdriver, push the piston from the back with two fingers over the line ports on the master, It takes some practice but you can do it. Push the piston in a few times until the bubbles stop rising to the top of the reservoirs. Fill it up, leave some space, an 1/8" will do, lock the cover down and install the master. Then bleed it at the 4 wheels.

Bob

If by now you're this messed up with it, have it towed to a shop and get it fixed right. You should be able to build pressure with the car off, your brakes WILL work with the engine off. Look for a kinked line in the area where you worked on the struts. Are you losing fluid?

You may have pushed the master past the normal range of travel. When they get old, there is a ring of rust in the piston bore that comes from condensation on the bare cast iron surface. If you push the piston past it (which you did if it goes to the floor) the chances of scoring the cups is great. The leak might be external or internal (bypassing), take a look at the base of the master where it meets the power booster.

To rule out a bad power booster (probably not your problem), shut the engine off, pump the pedal until all the vacuum is out of it and the pedal is hard. With your foot on the pedal, start the engine. The pedal should sink a little, if it doesn't, either the booster or check valve might be bad.

So, check all your lines for leaks, eyeball the master, make sure all of your bleeders are closed. Start with the RR wheel, try and bleed it again. Have the pedal person apply light pressure but not down to the stop. If by 4-5 shots it still spits mostly air, I would suspect that the master is bad.

I trust that you know how to bleed brakes. You have to talk with the pedal pusher, tell him "up", "down", "hold it down" and "go easy". They have to answer you back. Sounds silly, but it works. Never ever have someone let up on the pedal when the bleeder is open, which makes the task infinitely worse.

If you decide to change the master, you have to "bench bleed" it first. I use this method: Lock it in a bench vise first. Fill the master, leave the top off. Take a big screwdriver, push the piston from the back with two fingers over the line ports on the master, It takes some practice but you can do it. Push the piston in a few times until the bubbles stop rising to the top of the reservoirs. Fill it up, leave some space, an 1/8" will do, lock the cover down and install the master. Then bleed it at the 4 wheels.

Bob




After bleeding them twice I can finally build up some pressure with the car off. But turn it on and it still doesn't stop the car properly. From what you say its the master cylinder thats bad. But how can taking apart a single brake line on the back make the master cylinder die?

After bleeding them twice I can finally build up some pressure with the car off. But turn it on and it still doesn't stop the car properly. From what you say its the master cylinder thats bad. But how can taking apart a single brake line on the back make the master cylinder die?

You probably pushed the master cylinder too far and damaged one of the internal cups, which are rubber. Like I said earlier, at the bottom of the piston bore, you get an accumulation of old fluid which mixes with condensation and builds up a ring forming the hard ridge. Once the cup on the piston passes over it, the damage is done.

Bob