self bleeding of brakes

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My dad years ago told me that over time most air bubbles in the brake lines would work their out into the master cylinder. I am positive this had some truth to it. So 3 questions: 1) More likely for old brakes rather than new ABS brakes? 2) More likely if the air cam in from low fluid in master cylinder? 3) More likely if air cam in via a caliper or wheel cylinder change?
 
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Bleeding the brakes is super-important with ABS as air can create more of a dangerous safety hazard if the control module is processing air and not fluid in a critical braking situation. If the system is always topped up and the brake fluid is flushed regularly you should never have an accumulation of air in the system to worry about. Small price to pay for safety, with brakes you never mess around or it could be the last thing you ever do. \:\!
 
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Some cars do seem to lend themselves to "self bleeding", but in most cars there are places the air can get trapped and you cannot clear it without proper bleeding. On some stubborn situations, more than one bleeding technique may be needed.
 
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You also have to remember that the inside of brake calipers is rough cast iron and will hold air bubbles. A quart of brake fluid is about 8 bucks canadian (1 quart is usually enough for a full system flush on most cars), so every 2 to 3 years this is one of the least expensive maintenance items, especially for a DIY'er. Yet, it is one of the most ignored along with ATF and coolant flushes.
 
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 Originally Posted By: Big Jim
Some cars do seem to lend themselves to "self bleeding", but in most cars there are places the air can get trapped and you cannot clear it without proper bleeding. On some stubborn situations, more than one bleeding technique may be needed.
My Santa Fe has self-bleeding calipers and at the MC, but I still bleed manually for the reasons you described. ;\) An ounce of prevention is worth a pound of cure!
 

Donald

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What happens when you snap a bleeder screw on a caliper? Does it leak brake fluid or just a PIA to fix (Replace caliper). Yes I will use PB Blaster first.
 
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The bleeder screw seals when it's seated so if you snap it off and it hasn't moved you're okay for the moment. Use a six-sided wrench or socket to break the bleeder loose, they are easy to round off if they are stuck.
 
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To open a bleeder screw. Put a box wrench of the correct size on the screw. Hit the screw on the top sharply with a small hammer to jar it. It should unscrew easily. You only need to turn the screw 1/2 turn or so to slightly open. The seating torque is very small so don't over tighten.
 
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Like Big Jim said, some air will work itself out. Sometimes quite a bit. But it is foolish to rely on time and luck for your brakes.
 
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