I keep losing brake pressure
08-03-04, 07:05 PM
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I keep losing brake pressure
Ever since I have had my RX-7 I have never been able to get anything near good brake pressure. I have bled the system 3 different times so I doubt that its me bleeding them wrong. Could it be a bad master cyllinder? Any advice on getting rid of this incredibly annoying problem would be appreciated.
ps I have almost no pressure now...
ps I have almost no pressure now...
08-03-04, 07:29 PM
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If you're sure they're bled properly, Check for leaks around brake lines and hoses. Assuming there is none, replace that cylinder ASAP.. they're really not that expensive, and brakes are NOT something you want to be screwing around with.
08-03-04, 08:36 PM
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Originally Posted by rotarygod
Make sure you have the one way valve in the brake booster air line. I removed it once accidentally when I was doing some work and the car could not maintain brake pressure. The pedal would rapidly hit the floor.
08-03-04, 11:11 PM
#6
That is true. With the available info though it just seemed like this could be a problem. He only stated pressure but not where the pressure was. Brake pedal pressure? Actual pressure in the lines? Without that valve you will have pedal for a short time but it will fade really quick.
08-04-04, 12:30 AM
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I have no pressure in the brake pedal and when I push the pedal down the brakes do very little to slow the car. I have not touched the booster or master cyllinder so far. I replaced a caliper and have bled the lines. Other than that, I have not touched the brake components.
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08-04-04, 12:55 AM
#8
That is still pretty vague. It could be anything. That's not much more info than saying, my car is broken how do I fix it?
When you bleed the brakes, do you still get air out of it? If so, how much? I use an air compressor with a needle attachment that is used to fill basketballs, footballs, etc. I keep air pressure fairly low and blow it into the little hole on top of the master cylinder. I always let a friend help. He opens the brake bleeder lines and I keep the pressure on until the bubbles stop. I do this to all 4 wheels and then go back and do it again just to be safe. If you still have no pressure, this isn't the issue. If you still get air in the lines no matter how much you bleed it, there is a leak somewhere. If you have no leaks and no air in the lines, you may have a bad one way valve on the master cylinder air line. This will effectively render your brakes useless and pushing the pedal will have no effect. If this is OK then check the master cylinder for leaks or a blown seal. See if you are leaking brake fluid into the passenger compartment through the firewall. If this is fine you may still have a piston that is bad in one of the calipers. Doubtful if you've gotten this far. Check all of your lines for kinks. Be absolutely sure you have brake fluid and not another fluid in the reservoir. These should keep you busy enough checking things to narrow it down to the real problem. I can't think of anything else it can be if you have eliminated all of these possibilities.
When you bleed the brakes, do you still get air out of it? If so, how much? I use an air compressor with a needle attachment that is used to fill basketballs, footballs, etc. I keep air pressure fairly low and blow it into the little hole on top of the master cylinder. I always let a friend help. He opens the brake bleeder lines and I keep the pressure on until the bubbles stop. I do this to all 4 wheels and then go back and do it again just to be safe. If you still have no pressure, this isn't the issue. If you still get air in the lines no matter how much you bleed it, there is a leak somewhere. If you have no leaks and no air in the lines, you may have a bad one way valve on the master cylinder air line. This will effectively render your brakes useless and pushing the pedal will have no effect. If this is OK then check the master cylinder for leaks or a blown seal. See if you are leaking brake fluid into the passenger compartment through the firewall. If this is fine you may still have a piston that is bad in one of the calipers. Doubtful if you've gotten this far. Check all of your lines for kinks. Be absolutely sure you have brake fluid and not another fluid in the reservoir. These should keep you busy enough checking things to narrow it down to the real problem. I can't think of anything else it can be if you have eliminated all of these possibilities.
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