My PB seem a little soft. Looking for help on the procedure to bleed lines.
jim larson said
Sep 12, 2014
I rebuilt the MC last winter and also had a guy in CA rebuild and re-plate the Booster last winter. I think I may have a little air in the lines, as I did not bleed the lines. I tired not to let air in when I removed the MC; but who knows. I refilled and bleed the MC on the bench before putting it back on the car.
I just think I have to lean on the pedal harder. So I am going to bleed the lines. I saw somewhere here in the past about Mitch just using gravity to bleed the lines. Fill the MC and go in the house for coffee and then come back. Can someone explain this is more detail. How long do I spend in the house with the coffee cup? How do I make sure the MC doesn't go dry and air get in the system, how much fluid has to go though the system to the rear right to make sure all the air is out, etc? Thanks.
Derek69SS said
Sep 12, 2014
I do the gravity bleed as well, and only resort to other measures if absolutely necessary (rarely)
I usually run a whole quart bottle through just for the sake of flushing the whole system with fresh fluid at the same time.
I've had stubborn ones that I left open overnight to flow, and I've had others that would run dry in 1/2-hour. I usually like to find something else to do in the shop while doing it so I can keep an eye on it and not run it dry.
jim larson said
Sep 12, 2014
Thanks for the information Derek. Does the drain run linearly, like if it take 1 hr for 1/2 a pint, it will take 4 hr for a quart?
Derek69SS said
Sep 12, 2014
you can only put a little bit in the master cylinder at a time... won't hold more than maybe 1/4 of a pint.
I stole a measuring cup out of the kitchen to pour the fluid in easier without spilling (and damaging paint).
Got in trouble over that one.
Derek69SS said
Sep 12, 2014
One thing to note is that you only want to open one bleeder at a time if you have a single reservoir, and only one front/one rear with dual reservoir.
If you open more than one on the same reservoir, the highest will drain to the lowest and suck in more air.
Lost in the 60s said
Sep 13, 2014
Jim, if you get 1 to 1 1/2 cups out of the right rear, that should be plenty to have flushed the lines twice. I then bleed the left rear of a 1/4-1/2 cup. It only needs to come from the T on the diff. In the case of a single master, then drain 1 cup from the right front and 1/4-1/2 from the left. I still have my wife pressure bleed them a few times too, as a bubble can get stuck in a wheel cylinder.
As Derek said, check the master often to prevent getting low and I'll state the obvious here, leave the cap loose while gravity bleeding.
jim larson said
Sep 13, 2014
So if I understand, do the gravity pressure bleed thing on all 4 wheels. Then come back and do the pressure bleed with a helper to get any air bubbles out that might have stuck in a cylinder.
Lost in the 60s said
Sep 13, 2014
jim larson wrote:
So if I understand, do the gravity pressure bleed thing on all 4 wheels. Then come back and do the pressure bleed with a helper to get any air bubbles out that might have stuck in a cylinder.
That's my routine to be certain it's all out...
jim larson said
Sep 13, 2014
The gravity system doesn't seem to work for me. I've watched some you-tube video's and think I am doing things right. So I just had to wife pump the brakes until I ran 2 cups through the right rear and 1 cup though the left rear.
Wife left for lunch, what's new, so I am going to try the gravity system on the front right. Maybe I am to impatient. How long to run 1/2 a cup through? 1 hr, 2hr, 3hr, or more?
Lost in the 60s said
Sep 13, 2014
jim larson wrote:
The gravity system doesn't seem to work for me. I've watched some you-tube video's and think I am doing things right. So I just had to wife pump the brakes until I ran 2 cups through the right rear and 1 cup though the left rear.
Wife left for lunch, what's new, so I am going to try the gravity system on the front right. Maybe I am to impatient. How long to run 1/2 a cup through? 1 hr, 2hr, 3hr, or more?
All depends on how fast it drips out. For the gravity, I turn the bleeder out a couple turns, just cracking it like a pressure bleed won't produce much flow. I've had a 1/2 cup drain out the rear in 1/2 hr.
I rebuilt the MC last winter and also had a guy in CA rebuild and re-plate the Booster last winter. I think I may have a little air in the lines, as I did not bleed the lines. I tired not to let air in when I removed the MC; but who knows. I refilled and bleed the MC on the bench before putting it back on the car.
I just think I have to lean on the pedal harder. So I am going to bleed the lines. I saw somewhere here in the past about Mitch just using gravity to bleed the lines. Fill the MC and go in the house for coffee and then come back. Can someone explain this is more detail. How long do I spend in the house with the coffee cup? How do I make sure the MC doesn't go dry and air get in the system, how much fluid has to go though the system to the rear right to make sure all the air is out, etc? Thanks.
I usually run a whole quart bottle through just for the sake of flushing the whole system with fresh fluid at the same time.
I've had stubborn ones that I left open overnight to flow, and I've had others that would run dry in 1/2-hour. I usually like to find something else to do in the shop while doing it so I can keep an eye on it and not run it dry.
Thanks for the information Derek. Does the drain run linearly, like if it take 1 hr for 1/2 a pint, it will take 4 hr for a quart?
you can only put a little bit in the master cylinder at a time... won't hold more than maybe 1/4 of a pint.
I stole a measuring cup out of the kitchen to pour the fluid in easier without spilling (and damaging paint).
Got in trouble over that one.
One thing to note is that you only want to open one bleeder at a time if you have a single reservoir, and only one front/one rear with dual reservoir.
If you open more than one on the same reservoir, the highest will drain to the lowest and suck in more air.
As Derek said, check the master often to prevent getting low and I'll state the obvious here, leave the cap loose while gravity bleeding.
So if I understand, do the gravity pressure bleed thing on all 4 wheels. Then come back and do the pressure bleed with a helper to get any air bubbles out that might have stuck in a cylinder.
That's my routine to be certain it's all out...
The gravity system doesn't seem to work for me. I've watched some you-tube video's and think I am doing things right. So I just had to wife pump the brakes until I ran 2 cups through the right rear and 1 cup though the left rear.
Wife left for lunch, what's new, so I am going to try the gravity system on the front right. Maybe I am to impatient. How long to run 1/2 a cup through? 1 hr, 2hr, 3hr, or more?
All depends on how fast it drips out. For the gravity, I turn the bleeder out a couple turns, just cracking it like a pressure bleed won't produce much flow. I've had a 1/2 cup drain out the rear in 1/2 hr.