[rebel-builders] Air bubble in the brake system

[Jose & Terry]

Hello, my two cents, when you bleed you do it from reservoir to bleeder (
you can also suck with vac pump on the bleeder ). On the pressure stroke
loosen the bleeder, let pressure out until oil/air stops coming from the
bleeder, then tighten the bleeder before releasing the handle or pedal. On
the release stroke the master cylinder will draw in oil from the
reservoir, if your bleeder is open during the up stroke it is possible to
draw in air through it. Before pushing on the pedal/handle again give it a
couple of seconds for the oil to be drawn into the system (watch the oil go
down in the reservoir, don't let it get empty or you have to start over ).
You have to open and close the bleeder on every stroke. You could let
gravity bleed the lines by leaving the bleeder(s) open and keeping the
reservoir full as it goes down. If your reservoir holds a half litre oil
bleed out this much at least and you will be sure there is no air left. As
long as your reservoir is the high point ( no loops or lines above it ) you
will not have any air left in any lines even if you have loops below it. If
after this you still have air in the lines it is possible you have a leak
somewhere on the suction side of your master cylinder or the cylinder itself
is defective. You can check this by deadheading the cylinder ( plug the
end ) and push the pedal/handle and see if it holds or completes a stroke.
Watch for leaks during this test. Before doing anything check all your
connections and that no lines go above the reservoir oil level

Hope this helps, Jose


----- Original Message -----
From: "Jay Yau" <jayyau28@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, April 27, 2010 2:49 PM
Subject: [rebel-builders] Air bubble in the brake system

I bled the brake fluid twice, still found the same amount of air bubble in
the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the
way though with a pump I bought from aircraft spruce (pump the fluid into
the bleeder nipple and drain out of of reservor on the top). But after
settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay


_________________________________________________________________
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with
Hotmail.
http://www.windowslive.com/campaign/the ... P:042010_5



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Ken]

Jay

Try it. Is the pedal spongy or firm? It may be just fine.
That is not much air in a .117" id tube. There is almost always a tiny
bit of air trapped in the high spots of a fitting or somewhere unless
you pump the fluid fairly fast while bleeding the system.

I think I had a small bubble or two but it was not noticeable in use. I
used a hand pumped oil can but it sounds like you are doing it
correctly. Fluid in the bottom port and air bubbles out the top port and
up to the reservoir. This is opposite to bleeding a car but a car has
the air bleed ports on the top of the caliper among other differences.

Ken

Jay Yau wrote:

I bled the brake fluid twice, still found the same amount of air bubble in the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the way though with a pump I bought from aircraft spruce (pump the fluid into the bleeder nipple and drain out of of reservor on the top). But after settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Jose & Terry]

Ken,

I guess I spoke too soon, I can't find the brake caliper install section in
my book and just assumed the bleeders were on top, like a car. Being on the
bottom means for sure pump up. I went on line and found a good description
of how to do it, just like you describe. Check out this site.


http://www.groveaircraft.com/brakeinstall.html

Jose



----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, April 27, 2010 7:07 PM
Subject: Re: [rebel-builders] Air bubble in the brake system

Jay

Try it. Is the pedal spongy or firm? It may be just fine.
That is not much air in a .117" id tube. There is almost always a tiny
bit of air trapped in the high spots of a fitting or somewhere unless
you pump the fluid fairly fast while bleeding the system.

I think I had a small bubble or two but it was not noticeable in use. I
used a hand pumped oil can but it sounds like you are doing it
correctly. Fluid in the bottom port and air bubbles out the top port and
up to the reservoir. This is opposite to bleeding a car but a car has
the air bleed ports on the top of the caliper among other differences.

Ken

Jay Yau wrote:

I bled the brake fluid twice, still found the same amount of air bubble
in the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the
way though with a pump I bought from aircraft spruce (pump the fluid into
the bleeder nipple and drain out of of reservor on the top). But after
settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Jay Yau]

Ken,



Thank you so much for the advise.



The pedal does feel spongy, the master brake cylinder travels twice the distance compare to the other side, it's very dangerous while applying brakes to stop the airplane during landing and trying to get off the runway as quickly as I can, because both pedal travel two different distance, one side of brake may lock tighter than the other, so the nose veer off the runway.



I use Aircraft Spruce "Hydraulic brake bleeder tank" to bleed the system, so far has done it twice on the same side and with same amount of air bubble show up on the tube each time. I am pretty sure I had flushed everything out of the system, but after a while, the air bubble still showed up.



I'm thinking to fill the fluid from the top and bleed it off at the bottom.



Jay

Date: Tue, 27 Apr 2010 20:07:52 -0400
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Air bubble in the brake system

Jay

Try it. Is the pedal spongy or firm? It may be just fine.
That is not much air in a .117" id tube. There is almost always a tiny
bit of air trapped in the high spots of a fitting or somewhere unless
you pump the fluid fairly fast while bleeding the system.

I think I had a small bubble or two but it was not noticeable in use. I
used a hand pumped oil can but it sounds like you are doing it
correctly. Fluid in the bottom port and air bubbles out the top port and
up to the reservoir. This is opposite to bleeding a car but a car has
the air bleed ports on the top of the caliper among other differences.

Ken

Jay Yau wrote:

I bled the brake fluid twice, still found the same amount of air bubble in the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the way though with a pump I bought from aircraft spruce (pump the fluid into the bleeder nipple and drain out of of reservor on the top). But after settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail.
http://www.windowslive.com/campaign/the ... P:042010_4



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Jay Yau]

Jose,



Thanks for the explanation how the master cylinder works, I'll check for possible defective cylinder.



Jay

From: tj22@mts.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Air bubble in the brake system
Date: Tue, 27 Apr 2010 16:56:59 -0500

Hello, my two cents, when you bleed you do it from reservoir to bleeder (
you can also suck with vac pump on the bleeder ). On the pressure stroke
loosen the bleeder, let pressure out until oil/air stops coming from the
bleeder, then tighten the bleeder before releasing the handle or pedal. On
the release stroke the master cylinder will draw in oil from the
reservoir, if your bleeder is open during the up stroke it is possible to
draw in air through it. Before pushing on the pedal/handle again give it a
couple of seconds for the oil to be drawn into the system (watch the oil go
down in the reservoir, don't let it get empty or you have to start over ).
You have to open and close the bleeder on every stroke. You could let
gravity bleed the lines by leaving the bleeder(s) open and keeping the
reservoir full as it goes down. If your reservoir holds a half litre oil
bleed out this much at least and you will be sure there is no air left. As
long as your reservoir is the high point ( no loops or lines above it ) you
will not have any air left in any lines even if you have loops below it. If
after this you still have air in the lines it is possible you have a leak
somewhere on the suction side of your master cylinder or the cylinder itself
is defective. You can check this by deadheading the cylinder ( plug the
end ) and push the pedal/handle and see if it holds or completes a stroke.
Watch for leaks during this test. Before doing anything check all your
connections and that no lines go above the reservoir oil level

Hope this helps, Jose


----- Original Message -----
From: "Jay Yau" <jayyau28@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, April 27, 2010 2:49 PM
Subject: [rebel-builders] Air bubble in the brake system

I bled the brake fluid twice, still found the same amount of air bubble in
the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the
way though with a pump I bought from aircraft spruce (pump the fluid into
the bleeder nipple and drain out of of reservor on the top). But after
settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay


_________________________________________________________________
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with
Hotmail.
http://www.windowslive.com/campaign/the ... P:042010_5



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

_________________________________________________________________
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail.
http://www.windowslive.com/campaign/the ... P:042010_5



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Jay Yau]

Hi Guys,

I bled the brake fluid from the bottom up 3 times, could never get rid of air bubble in the line, finally I bled the fluid from the top to the bottom and it got rid of the air completely. That means, both Master Cylinder and Caliper were not defective. I am so glad that it was just some air bubble trapped in the system, but where and how?
any one has similar experience?

I changed the brake pads today, I used Rapco brake rivet tool to do the work, local pilot told me, never drill the rivet out, just use the Rapco tool to remove the rivet, but I found the front of the rivet hole was enlarged a little bit when I squeezed the rivet head out, is that normal? And I also found one side of the pad rivet becomes a little too shorter due to a thicker aluminum plate (1mm thicker compare to the other side), any advise of getting a longer rivet?

Jay

From: tj22@mts.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Air bubble in the brake system
Date: Tue, 27 Apr 2010 16:56:59 -0500

Hello, my two cents, when you bleed you do it from reservoir to bleeder (
you can also suck with vac pump on the bleeder ). On the pressure stroke
loosen the bleeder, let pressure out until oil/air stops coming from the
bleeder, then tighten the bleeder before releasing the handle or pedal. On
the release stroke the master cylinder will draw in oil from the
reservoir, if your bleeder is open during the up stroke it is possible to
draw in air through it. Before pushing on the pedal/handle again give it a
couple of seconds for the oil to be drawn into the system (watch the oil go
down in the reservoir, don't let it get empty or you have to start over ).
You have to open and close the bleeder on every stroke. You could let
gravity bleed the lines by leaving the bleeder(s) open and keeping the
reservoir full as it goes down. If your reservoir holds a half litre oil
bleed out this much at least and you will be sure there is no air left. As
long as your reservoir is the high point ( no loops or lines above it ) you
will not have any air left in any lines even if you have loops below it. If
after this you still have air in the lines it is possible you have a leak
somewhere on the suction side of your master cylinder or the cylinder itself
is defective. You can check this by deadheading the cylinder ( plug the
end ) and push the pedal/handle and see if it holds or completes a stroke.
Watch for leaks during this test. Before doing anything check all your
connections and that no lines go above the reservoir oil level

Hope this helps, Jose


----- Original Message -----
From: "Jay Yau" <jayyau28@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, April 27, 2010 2:49 PM
Subject: [rebel-builders] Air bubble in the brake system

I bled the brake fluid twice, still found the same amount of air bubble in
the nylon tube (about 1.5 inches long of the air bubble).



I am pretty sure that I have pumped the fluid from the bottom up all the
way though with a pump I bought from aircraft spruce (pump the fluid into
the bleeder nipple and drain out of of reservor on the top). But after
settled down for while, still see air bubble in the tube.



Any one has similar problem?



Should I flush the fluid the other way around, from top to the bottom?



Jay


_________________________________________________________________
The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with
Hotmail.
http://www.windowslive.com/campaign/the ... P:042010_5



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

_________________________________________________________________
The New Busy is not the old busy. Search, chat and e-mail from your inbox.
http://www.windowslive.com/campaign/the ... P:042010_3



-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------