brake bleeding
brake bleeding question
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Logistics Pro
Joined: Jan 2001
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From: Connecticut
brake bleeding question
Hi all
With a manual brake system, If I pump up the brakes about 5 times (with engine off) and then wait a few minutes, THEN open a wheel cylinder, should there still be any pressure in the system???????
I can open a bleeder and the fluid will shoot out a couple of inches, then just ooze out for a bit. Is this normal???
Thanks
Reamer
With a manual brake system, If I pump up the brakes about 5 times (with engine off) and then wait a few minutes, THEN open a wheel cylinder, should there still be any pressure in the system???????
I can open a bleeder and the fluid will shoot out a couple of inches, then just ooze out for a bit. Is this normal???
Thanks
Reamer
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Joined: Feb 2005
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From: HANNIBAL MO.
I"m not sure but I don't belive ther should be any pressure on the brakes.If so I think your brakes would drag.I've heard of the rubber line going bad and keeping the fluid from backing off.
ART
ART
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From: Connecticut
Yes, I know this.
I have been having a problem where you touch the brake and they lock up and stay locked up. I removed the Power booster from the system. And now have "Manual Brakes."
The brakes seem to release now, but there is residual pressure in the system.
I'm thinking the residual pressure is being magnified by the booster and causing the hard lock up that won't release.
Therefor the original question. After pumping the brakes with engine off, And you wait a few minutes, should there be pressure in the system, or should there be no pressure?
I have been having a problem where you touch the brake and they lock up and stay locked up. I removed the Power booster from the system. And now have "Manual Brakes."
The brakes seem to release now, but there is residual pressure in the system.
I'm thinking the residual pressure is being magnified by the booster and causing the hard lock up that won't release.
Therefor the original question. After pumping the brakes with engine off, And you wait a few minutes, should there be pressure in the system, or should there be no pressure?
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Roast em' if you got 'em
Joined: Mar 2005
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From: Rio Rancho, NM
The pressure should release as you release the pedal. Are you using residual valves? if so they are designed to hold a bit of pressure in the system but it shouldn't be enough to apply the brakes.
Check the adjustment of the actuator rod between the brake pedal pivot and the master cylinder. It sounds like it could be too long and not allowing the MC to fully release.
Good luck
Bobby
Check the adjustment of the actuator rod between the brake pedal pivot and the master cylinder. It sounds like it could be too long and not allowing the MC to fully release.
Good luck
Bobby
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Logistics Pro
Joined: Jan 2001
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From: Connecticut
Thats What I was thinking too.
I have the rod backed off to a point where there is a gap between the rod and cylinder, so if the MC wants full travel back, it's got it!
Reamer
I have the rod backed off to a point where there is a gap between the rod and cylinder, so if the MC wants full travel back, it's got it!
Reamer
Roast em' if you got 'em
Joined: Mar 2005
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From: Rio Rancho, NM
HHMMMM
And you said all the rubber parts and hoses are new? what about the hard lines? Maybe one of them has some blockage.
Its a new master cylinder? or did you rebuild it? Did all of this start after you put it all back together or was it there before?
Very interesting (and a bummer)
Bobby
And you said all the rubber parts and hoses are new? what about the hard lines? Maybe one of them has some blockage.
Its a new master cylinder? or did you rebuild it? Did all of this start after you put it all back together or was it there before?
Very interesting (and a bummer)
Bobby
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Joined: Sep 2004
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From: Grain Valley Mo.
Originally Posted by himmelberg
Sounds like air trapped in there.
stopping well, himmelberg
stopping well, himmelberg
Just slightly off the subject: I used the "one way" bleeder valves on the wheel cylinders, and they are worth the money.IMO. When you use these it's impossible to leave air in the system, assuming you keep the master topped off while your bleeding.
Roast em' if you got 'em
Joined: Mar 2005
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From: Rio Rancho, NM
Boy, this is a head scratcher for sure.
Is it a dual place master cylinder? or can you diffrerentiate between the front and back? is it worse in the front or back?
There is a remote chance that somewhere in the system there is a small piece of trash that is only allowing fluid to flow in one direction. This is a pretty small chance. You could try pulling all the lines loose and blowing them out in both directions.
Do you have another master cylinder you can try? Maybe put the old one back on there and see how it acts. I'm thinking that something in your new master cylinder isn't right.
Very strange
Bobby
Is it a dual place master cylinder? or can you diffrerentiate between the front and back? is it worse in the front or back?
There is a remote chance that somewhere in the system there is a small piece of trash that is only allowing fluid to flow in one direction. This is a pretty small chance. You could try pulling all the lines loose and blowing them out in both directions.
Do you have another master cylinder you can try? Maybe put the old one back on there and see how it acts. I'm thinking that something in your new master cylinder isn't right.
Very strange
Bobby
Junior User
Joined: Dec 2004
Posts: 83
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From: Cedar Rapids, IA
reamer,
As far as the fluid shooting out of the bleeders after the pedal has been let off, that is normal for a system with residual pressure valves (read a master cylinder built for drum brakes). A disk brake MC may have a VERY small residual pressure valve (like 2psi) or none at all, but a drum brake MC has like 15 psi residual pressure valves in it, typically. As far as your brakes locking up, it really sounds like a problem with the actuator valve in the booster, as you mentioned that the brakes unlocked when you disconnected your vaccuum booster line (this was in another thread). I really would try another booster on your system.
As far as the fluid shooting out of the bleeders after the pedal has been let off, that is normal for a system with residual pressure valves (read a master cylinder built for drum brakes). A disk brake MC may have a VERY small residual pressure valve (like 2psi) or none at all, but a drum brake MC has like 15 psi residual pressure valves in it, typically. As far as your brakes locking up, it really sounds like a problem with the actuator valve in the booster, as you mentioned that the brakes unlocked when you disconnected your vaccuum booster line (this was in another thread). I really would try another booster on your system.
New User
Joined: Jul 2003
Posts: 12
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From: Rural missouri
I had the same trouble with a 46 Ford Coupe that I mounted a 72 chevy power brake system in and the problem was the rod that fits in the booster was too long. I shortened it about a quarter inch and that fixed the problem