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Posted by Ace_gst, Mar 15, 2012
Handling Tech - 4G63 suspension, steering, brakes, tires, lightweight wheels, bushings, etc.
Go over every inch of your lines. If your fluid is going down, find where it is going.
Just to add some info this is my first time messing with the brakes on the car i just got it running.
Ill let every one know if it was the cylinder.
The booster isn't required in order for the brakes to function properly, all it does is make them more sensitive to foot pressure -- hence the word "booster". Your brakes should function correctly with the engine off parked in the garage, you'll just have to push harder. If they don't, then the problem is somewhere in the hydraulic system.
Well, if the brakes don't work (with or without the booster), you can be assured you have an hydraulic leak. Hopefully it's the MC, but if not, then it's something else in the chain -- best wishes, dude !
Let us know how you bleed the line, so we can think on what could be the problem.
It looks to me like, there still air in the lines.
Where is this check valve at?
How did you bleed them?. What method did you use?.
Did you drain the oil and put more oil in the reservoir?.
Did you bleed it from the line where meet the caliper, or from the valve bleeder?.
Did some one help you to push the brakes while you bleed it?.
Let us know how exactly you bleed each line.
hdamn but i think i worked all the air out the fronts.
You shouldn't drain the reservoir, Draining the reservoir makes the system to get more air.
Did you bleed the lines at the cylinder?.
If you didn't, then you still have air in the system.
Draining the oil in the reservoir, will allowed the air to get into the lines and more bleeding is required.
Imagine, Air going into the cylinder and getting out of the caliper, that will take a lot of oil bleeding, Keep bleeding until you think that is enough oil bleed it.
The air has to run from the cylinder to the lines (from the cylinder to the Valve), then passes to the valve, then goes to the lines again (from the valve to the caliper), and last, goes out to the caliper.. That requires some kind of oil,,, Keep draining But never let the reservoir to get low, other wise you will never bleed the air from the lines.
The rear lines will take more time to bleed which they are more longer then the front, so be patient.
It shouldn't be backwards?.
If there is vaccum leak at the booster, then after you push the brake, it has to be harder, not lighter, which leaking air from the booster gives less assistance from the booster and makes the pedal harder, which is totally opposite from air in the system, which it is a light felling in the pedal.
I don't know if I understood what you were trying to say.
IT could be that it is only leaking when you push the pedal. There is no other reason for the engine to go lean other than a vacuum leak in the booster.
OP: You have air in your lines for sure. Try bleeding the master cylinder by cracking one line at a time on the master while someone gently pushes down on the pedal- dont pump it, itll make a mess. Have a towel to hold and catch the fluid so it doesnt spew everywhere. After the master is free of air, bleed the Passenger rear, Driver rear, Passenger front and Driver front.
The valve that Miquel is talking about is the proportioning valve, not the check valve. Ignore him.
The check valve is the lump in the hose between the intake and the booster. When it's broken (or backwards), you'll have the symptoms described by the OP. Verify that air can flow from the booster to the intake, but not the other direction. If the valve passes this test, move on to checking the booster, itself, for leaks, as suggested by Bryan.
I had a no-brakes situation after i left my car sit for over a year. At the time I was also diagnosing a poor idle and running condition.
Whenever I pumped the brakes my car would stall out and die. The only way I could build pressure in my brake system was to rev it up and pump the brakes repeatedly. It would immediately want to die, and pressure in the brake would decrease quickly.
I immediately figured my Brake Booster was leaky cause of the idle dropping. So i popped another one in the car and had the exact same situation. I checked the one way valve in the booster line and it was good. *note a good check for the brake booster is to put a vacuum line up to the BB and bypass the check valve and then attach it to pressurized air. it should not leak! Just don't over pressurize it.
So I ordered a master cylinder after bleeding all my lines and still having the same problem. Once I got master cylinder hooked up, it was all good. But make sure you bleed the lines correctly, just like kchaaz said.
Also iv been bleeding with car off should i try with it running.