Bleeding MC on car
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From: NY
Bleeding MC on car
I installed my new brake master cylinder today and since I don't have a vice, I decided to bleed it on the car. I first bolted it on and then filled it with fluid and left the top off. Once the fluid started to drip out, I installed the plastic threaded plugs. I then very slowly depressed the pedal 1 inch at a time until it just barely touched the floor. And there it remains. Will the pedal come back up by itself, or will I need to pull it back up slowly by hand? Or am I done bleeding? I'm sure it will come back up once I put the lines on it, I'm just confused about the bleeding process for the MC. TIA.
Last edited by Ric80; Apr 16, 2005 at 09:45 PM.
Racer
Joined: Jul 2004
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From: California
i didnt even bother to benh bleed mine, i did what u did and bled it on the car, but i did it with everything hooked up and it worked just fine and the pedal camer back, so ya i think that the pedal will come back up when u hook it all up, since there is no pressure nothing will force it back up...kinda like having your throttle cable come off the stud...it just stays on the floor. lol
Race Director
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Ric80
I installed my new brake master cylinder today and since I don't have a vice, I decided to bleed it on the car. I first bolted it on and then filled it with fluid and left the top off. Once the fluid started to drip out, I installed the plastic threaded plugs. I then very slowly depressed the pedal 1 inch at a time until it just barely touched the floor. And there it remains. Will the pedal come back up by itself, or will I need to pull it back up slowly by hand? Or am I done bleeding? I'm sure it will come back up once I put the lines on it, I'm just confused about the bleeding process for the MC. TIA.
usually you use a tube that goes from the threaded plugs back to the resorvoir...and you pump unitl all air is removed from the MC.there is a spring inthe MC that should move the pedal back... i don't know why this isn't happening?
Drifting
Joined: Jan 2005
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From: Seabrook Texas
St. Jude Donor '05
What type of MC did you buy? Was it new? I suspect that the pedal will come back once you hook the lines up. When I bench bled mine I put the plugs in and just pushed it in an inch at a time until no bubbles came out. Took about 15 times. 
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From: NY
Originally Posted by swtato
What type of MC did you buy? Was it new? I suspect that the pedal will come back once you hook the lines up. When I bench bled mine I put the plugs in and just pushed it in an inch at a time until no bubbles came out. Took about 15 times.
Thanks everyone for the replies
Last edited by Ric80; Apr 16, 2005 at 10:40 PM.
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From: NY
Originally Posted by bobs77vet
usually you use a tube that goes from the threaded plugs back to the resorvoir...and you pump unitl all air is removed from the MC.there is a spring inthe MC that should move the pedal back... i don't know why this isn't happening?
Last edited by Ric80; Apr 16, 2005 at 10:43 PM.
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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St. Jude Donor '06-'10, '13
This is not my car, just a picture from the web, but this is how I did mine. They sell these kits at most auto stores. I slowly pumped the pedal back and forth until no more bubbles came out of the tubes. After that I hooked up the hard lines and then bled the whole system.
Safety Car
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you should of got those tubes/plastic fittings with the purchase of the master cylinder! they usually come in the same box as the master cylinder,in a plastic bag,,,,i just bought a chrome master,and the kit came with it,,,my son bought one 6mts ago and he also got the kit with it..... also i have 2 vises,,,,but didnt want to risk scratching the finish ,,so i put one of those rubber place mats(for a good grip) on the table and my dad and my wife held the master while i bench bled it with those hoses installed until no bubbles of air came out
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Race Director
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Ric80
yeah, I was thinking that maybe because I am using the plugs and not the tubes that it is somehow pressure locked? The top is off tho...and like EVIL_GRIM said, with no backpressure its just going to lay there on the floor like an old shoe
maybe i don't understand what you mean....but if you use plugs to block the outlet holes and your pushing in the barake your aren't doing anything....that picture is what you should be doing
Le Mans Master
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From: Wildwood IL
Me thinks those plugs you installed prevent the necessary venting for the MC plunger to return to normal. It has to suck something to return to the rest position, weather it's fluid or air. By installing the plugs, and pushing on the pedal...you crated a vacuum.
Eddie
Eddie
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From: Vail AZ
Just FYI, I have a large vice, but I don't use it to bench bleed master cylinders. I have found that it is much easier, and I get a more complete bleed by holding the master cylinder at chest-level and leaning the actuator rod into a fixed object to move it. I can change the angle of the M/C that way to get a complete bleed. The garage door jamb makes a great pedal-pusher.
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From: NY
I went out and checked the pedal this morning after it sat all night and it came back up and now continues to come back up after I depress it. I think maybe the piston didn't have enough fluid on it and got stuck because I didn't let it drip through the outlet ports long enough? One of the plugs was leaking which might have actually helped the piston get lubed. We tightened up the plug and no more drips. A friend and I bled and tapped it for about an hour, but its still bubbling slightly. Might have drawn in air through that leaking plug? We're going to let it sit a few hours and then have at it again, but I think we're on our way to bleeding this puppy.
After that, we'll hook up the lines. He suggested continuing to bleed it through the MC with the lines hooked up. Will that work?
Since we all love pics so much, here's a shot of the new MC:
After that, we'll hook up the lines. He suggested continuing to bleed it through the MC with the lines hooked up. Will that work?
Since we all love pics so much, here's a shot of the new MC:
Thread Starter
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From: NY
Originally Posted by tpiini
Just FYI, I have a large vice, but I don't use it to bench bleed master cylinders. I have found that it is much easier, and I get a more complete bleed by holding the master cylinder at chest-level and leaning the actuator rod into a fixed object to move it. I can change the angle of the M/C that way to get a complete bleed. The garage door jamb makes a great pedal-pusher.
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From: NY
Originally Posted by Silvr77
Me thinks those plugs you installed prevent the necessary venting for the MC plunger to return to normal. It has to suck something to return to the rest position, weather it's fluid or air. By installing the plugs, and pushing on the pedal...you crated a vacuum.
Eddie
Eddie
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From: Raleigh North Carolina
Originally Posted by Ric80
I installed my new brake master cylinder today and since I don't have a vice, I decided to bleed it on the car. I first bolted it on and then filled it with fluid and left the top off. Once the fluid started to drip out, I installed the plastic threaded plugs. I then very slowly depressed the pedal 1 inch at a time until it just barely touched the floor. And there it remains. Will the pedal come back up by itself, or will I need to pull it back up slowly by hand? Or am I done bleeding? I'm sure it will come back up once I put the lines on it, I'm just confused about the bleeding process for the MC. TIA.
1) The tolerances between the seals & the bore are at the tight end of the manufacturing range (not likely),
2) The one you got sat on the shelf for a long time and was already rusted on the inside.
In my experience, situation 2 is the more common.
After dealing with this several times in the distant past, I began religiously disassembling new and/or rebuilt master cylinders before I installed them. I found many rusty cylinders right off the shelf.
Tommy Target
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From: NY
Originally Posted by Tom454
After dealing with this several times in the distant past, I began religiously disassembling new and/or rebuilt master cylinders before I installed them. I found many rusty cylinders right off the shelf.
