There is so much experience and knowledge here that its hard to admit to a mistake, but here goes. Using the 2 person process with the 14 year old pumping the pedal, we let the master go dry....So we start over - rear passenger side inside, we are now on our second quart of fluid and there are still tiny bubbles (dot 3). Surely somebody else has done this, how much does it take after air has been introduced via the master cyl. or am I doing it wrong, again.
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Re: Brake Bleeding - messed up
I do not know if this is the correct procedure but it worked for me when I did a frame off and started from Zero. I started at the closest, Front left, and worked my way around to the Left rear. Now that I had fluid in the system I redid it by working back around. -
Re: Brake Bleeding - messed up
I do not know if this is the correct procedure but it worked for me when I did a frame off and started from Zero. I started at the closest, Front left, and worked my way around to the Left rear. Now that I had fluid in the system I redid it by working back around.Comment
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Re: Brake Bleeding - don't give up!
Hi John!
You didn't mention which year car you have. The system (hoses/cylinders/etc)is in good condition? 1967 and later cars use a dual-circuit master cylinder with separate bleeder ports. If this is the case, you will need to rebleed the master cylinder separately. If you have an early car, perhaps try tapping all the wheel cylinders (calipers 65-6) and master cylinder gently to free any trapped air pockets.
Other options include vacuum & gravity bleeding.
Hope this helps!
CarlComment
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Re: Brake Bleeding - don't give up!
Hi John!
You didn't mention which year car you have. The system (hoses/cylinders/etc)is in good condition? 1967 and later cars use a dual-circuit master cylinder with separate bleeder ports. If this is the case, you will need to rebleed the master cylinder separately. If you have an early car, perhaps try tapping all the wheel cylinders (calipers 65-6) and master cylinder gently to free any trapped air pockets.
Other options include vacuum & gravity bleeding.
Hope this helps!
CarlComment
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Minor Technicality- just a thought
With the "helper" method, be sure to open the bleeder ONLY as the helper is pressing the pedal, and close the bleeder BEFORE the pedal hits the floor. Otherwise, you will be re-introducing air each time you bleed a port. Also, only open the bleeder enough to allow the helpers foot to slowly press the pedal. If you open the bleeder too far, the pedal will go to the floor too quickly, and you won't be able to close the bleeder fast enough to prevent air from getting back into the system.Comment
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Minor Technicality- just a thought
With the "helper" method, be sure to open the bleeder ONLY as the helper is pressing the pedal, and close the bleeder BEFORE the pedal hits the floor. Otherwise, you will be re-introducing air each time you bleed a port. Also, only open the bleeder enough to allow the helpers foot to slowly press the pedal. If you open the bleeder too far, the pedal will go to the floor too quickly, and you won't be able to close the bleeder fast enough to prevent air from getting back into the system.Comment
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Re: Brake Bleeding - messed up
John----
Letting the master cylinder "go dry" is a common problem that many folks have experienced and survived. I'm sure you will, too. But here are a few comments:
First, the tiny bubbles of air that you're seeing might not be air entrained in the brake fluid, itself. Very often when bleeding calipers, air will leak around the bleeder screw threads and contribute to an endless and frustrating bleeding operation. To avoid this phenomenon, I apply silicone grease to the bleeder screw threads. This seals them and prevents the problem described.
Second, I recommend the use of the gravity bleeding method. Corvettes are very difficult to bleed properly. The gravity method can provide the surest method to remove all of the trapped air. Of course, the gravity method is slow. Also, you may need to apply a very small amount of over-pressure to the master cylinder to get the process started. To do this I use a master cylinder cap modified with a nipple in each dome and small tubing with a "T" connecting the nipples. Then I apply a very slight amount of pressure from the exhaust side of a MityVac pump. That gets the gravity process started. Of course, you need to first have each of the car's SIX bleeder screws open with clear tubing connected and immersed in jars of brake fluid.In Appreciation of John HinckleyComment
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Re: Brake Bleeding - messed up
John----
Letting the master cylinder "go dry" is a common problem that many folks have experienced and survived. I'm sure you will, too. But here are a few comments:
First, the tiny bubbles of air that you're seeing might not be air entrained in the brake fluid, itself. Very often when bleeding calipers, air will leak around the bleeder screw threads and contribute to an endless and frustrating bleeding operation. To avoid this phenomenon, I apply silicone grease to the bleeder screw threads. This seals them and prevents the problem described.
Second, I recommend the use of the gravity bleeding method. Corvettes are very difficult to bleed properly. The gravity method can provide the surest method to remove all of the trapped air. Of course, the gravity method is slow. Also, you may need to apply a very small amount of over-pressure to the master cylinder to get the process started. To do this I use a master cylinder cap modified with a nipple in each dome and small tubing with a "T" connecting the nipples. Then I apply a very slight amount of pressure from the exhaust side of a MityVac pump. That gets the gravity process started. Of course, you need to first have each of the car's SIX bleeder screws open with clear tubing connected and immersed in jars of brake fluid.In Appreciation of John HinckleyComment
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Re: Brake Bleeding - messed up/solved
Solved I hope. Went back out this AM, under the rear drivers side drops of fluid under the brake line block (uh oh), located small split in brake line. Not sure what happenned, I guess it was almost DOA (its original 70), better in the garage than on the road. Bit the bullet ordered new SS lines/rubber hoses. I sure had not planned on this, my "survivor" is turning into a frame-on restoration. Heavy sigh....Thanks for the help, with the gravity, will the fluid flow on its on once it is started or is a little constant pressure rqd.Comment
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Re: Brake Bleeding - messed up/solved
Solved I hope. Went back out this AM, under the rear drivers side drops of fluid under the brake line block (uh oh), located small split in brake line. Not sure what happenned, I guess it was almost DOA (its original 70), better in the garage than on the road. Bit the bullet ordered new SS lines/rubber hoses. I sure had not planned on this, my "survivor" is turning into a frame-on restoration. Heavy sigh....Thanks for the help, with the gravity, will the fluid flow on its on once it is started or is a little constant pressure rqd.Comment
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Energizer Fluid
John... Once it gets going, it usually just keeps on flowing. I have used the gravity method for 34 years and have found it to be the most error-free method. In a fast-paced commercial environment, the gravity method is totally un-acceptable due to the time consideration. But in your own garage, it's 100% effective. As Joe pointed out... a little "persuation" can speed things up, (substantially) although left to itself, the fluid eventually starts flowing all by its lonesome as long as the caliper is below the M/C.Comment
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Energizer Fluid
John... Once it gets going, it usually just keeps on flowing. I have used the gravity method for 34 years and have found it to be the most error-free method. In a fast-paced commercial environment, the gravity method is totally un-acceptable due to the time consideration. But in your own garage, it's 100% effective. As Joe pointed out... a little "persuation" can speed things up, (substantially) although left to itself, the fluid eventually starts flowing all by its lonesome as long as the caliper is below the M/C.Comment
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Gravity method
I have successfully used the two person method for 20+ years and have heard of the gravity method. I am basically familiar with it but I would like to hear from some of you who use this. Do you open all the bleeders at the same time and immerse all the tubes into jars with clean fluid or do you do it one at a time, starting at the right rear? Also, when you are gravity bleeding, how long do you leave the bleeders open before you go back and close them. Thanks, GaryComment
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Gravity method
I have successfully used the two person method for 20+ years and have heard of the gravity method. I am basically familiar with it but I would like to hear from some of you who use this. Do you open all the bleeders at the same time and immerse all the tubes into jars with clean fluid or do you do it one at a time, starting at the right rear? Also, when you are gravity bleeding, how long do you leave the bleeders open before you go back and close them. Thanks, GaryComment
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