Date: Fri, 19 May 2006 16:31:45 -0400
Reply-To: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Subject: Re: Still can't bleed Brake system
In-Reply-To: <00c101c67b53$7af92c50$f3e7fea9@dennistp4gtmxy>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Den,
I did clean out the reservoir when I had it off. That's good advice to
check the lines. I have heard of very strange behavior with corrosion in
those flex lines. But, I'm really not getting much flow directly out of
the MC for the front brake circuit. I think I will try again putting the
plastic hose in there and bleeding it back into the reservoir.
Edward
At 10:49 AM 5/19/2006, you wrote:
>Have you ever replaced the flex lines between the caliper and the steel
>line...
>
>To test, open the connection at the flex/steel and press the pedal...
>
>WEAR SAFETY GLASSES AS THE FLOW WILL BE SUBSTANTIAL
>
>I had the same issue, and new flex lines did the trick...I couldn't even
>blow through the old ones once I got them off...
>
>Additionally....did you flush the reservoir really well before you put it
>on the new master...I replaced two masters recently on Golf projects
>because the reservoirs/cylinders had mud in them...seems the fluid goes
>brown, then black when it breaks down...settles in the bottom of the
>reservoir where OMG it's right in the path to the master cylinder...talk
>about planned obsolescence....
>
>Good luck...
>
>Den.
>
>----- Original Message ----- From: "Edward Maglott"
><emaglott@BUNCOMBE.MAIN.NC.US>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Thursday, May 18, 2006 9:57 PM
>Subject: Still can't bleed Brake system
>
>
>>I still can't get the front brakes to bleed. Here's the latest I've
>>tried. I found that if I loosened the brake line from the MC for the rear
>>brakes and stepped on the pedal, I got a lot of brake fluid out of it. Not
>>so for the line going to the front brakes. I disconnected the line and
>>pressed the pedal. I got a little spit of fluid, but it seemed to be
>>mostly air. I put my finger over the hole for the brake line, and felt
>>pressure on depressing the pedal, and then suction on releasing the
>>pedal. Almost like the suction is greater than the pressure...
>>
>>I broke down and pulled the MC out to bleed it on the bench. I followed
>>some good instructions I found in the archives about putting plastic tubing
>>in the outlets and running them back into the reservoir. I think they were
>>5/16" OD tubing, FYI. They just wedge/screw into the outlets
>>perfectly. Pumped and pumped and got good flow from both outlets, and
>>pumped until there was little or no air. Put that whole apparatus back in
>>the van with the full tubing still in place. Carefully reconnected the
>>brake lines and tried again, but still nothing or very little at the front
>>brakes. I left the front bleeders open for 24 hours. The left front
>>caliper was pretty soaked w/ brake fluid, though not much in the tube on
>>the bleeder. Fluid seemed to be seeping out the bleeder threads... Rt
>>front caliper dry.
>>
>>Tried bleeding again, and thought I was making a little progress, then it
>>would get to the point of nothing really happening. I had my GF pumping
>>the pedal. She would push it down and hold, I would open the bleeder, and
>>the fluid would just barely creep up the tube an inch or so. If I didn't
>>close the bleeder, it would suck that fluid back in, and then a bunch of
>>air too. Again, it seems the MC is much more inclined to pull fluid back
>>in from the brake line than from the reservoir. I did a whole bunch of the
>>opening and closing with each pump she would do on the pedal, but no
>>improvement. Tried having her let the pedal back up slowly. Also opened
>>the rear bleeders so that the pedal would go all the way to the floor, but
>>that didn't help either.
>>
>>But wait, there's more! I rigged up a primitive pressure bleeder with air
>>compressor, piece of inner tube, block of wood. I had to hold it onto the
>>top of the reservoir, so I couldn't keep it pressurized for very long. But
>>I did see 20psi on the gauge, and still nothing coming out of the MC outlet
>>for the front brakes. Could this MC be defective? Its the $50 aftermarket
>>one from Bus Depot.
>>
>>Argh! Puzzled Edward
>>
>>
>>At 09:02 PM 5/15/2006, you wrote:
>>>The Vanagon brakes are split front/rear, not diagonal. That diagonal
>>>thing is mostly for light weight front drive cars. The front brakes are
>>>directly connected to the master cylinder. There is a rear brake
>>>pressure regulator, mounted on the right side from member near the spare
>>>tire. There is not an external lever or other bypass means.
>>>
>>>The most important part of brake bleeding if you do not have a pressure
>>>bleeder is patience. Fill the reservoir, open the bleeders and walk away
>>>for a while. If you are lucky, some fluid will gravity feed through. The
>>>hard part is getting the chamber in the master filled. Next, close all
>>>bleeders. See if there is any pedal firmness. If not, open left front,
>>>depress pedal, close bleeder, release pedal. You should see the fluid
>>>level in the reservoir drop slightly as the Master sucks it in. Again,
>>>open bleeder, depress pedal, close bleeder, release pedal. After left
>>>front has a good flow, go to right front, then go to rears, one at a
>>>time.
>>>
>>>Dennis
>>>
>>>-----Original Message-----
>>>From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
>>>Of Edward Maglott
>>>Sent: Monday, May 15, 2006 8:45 PM
>>>To: vanagon@GERRY.VANAGON.COM
>>>Subject: Brake system overview
>>>
>>>Still trying to bleed my brakes, and getting no, or very little fluid
>>>from
>>>the front calipers. See my original message below. Now I'm wondering
>>>if
>>>the 2 circuits coming from the master cylinder are really front and
>>>rear,
>>>not split diagonally like I thought. Can anybody confirm this? If so,
>>>which line from the MC is for the front brakes and which for the
>>>rear? Maybe I need to bleed the offending circuit of the MC better
>>>before
>>>trying to bleed the lines.
>>>
>>>Edward
>>>
>>> >Here's the short version of the events. Replaced Master cylinder.
>>>Broke
>>> >off a bleeder on one of the rear cylinders, so the project stalled. I
>>>went
>>> >out of town, etc, about 3 weeks pass. Anyway, put in the replacement
>>>rear
>>> >wheel cylinder, and start to bleed again. rear wheels bleeding fine.
>>>At
>>> >one point I was getting fluid out of LF, but I don't think the RF ever
>>>was
>>> >giving me much. Now I pump the pedal and then hold it to the floor,
>>>open
>>> >the bleeder and get a very slow minimal flow of fluid. The caliper is
>>> >actually loose like there is no pressure in it pushing on the piston.
>>>I
>>> >suppose it could be seized but I don't think so since it is only a
>>>year or
>>> >2 old. And the LF is doing the same thing now.
>>> >
>>> >Bentley talks about pushing the lever on the brake pressure regulator
>>> >toward the rear axe while bleeding. I think that instruction is from
>>> >another car, since there is no lever on the brake pressure
>>> >regulator. There is a procedure to test the Brake Pressure regulator,
>>> >that involves removing it from the body and tilting it forward. Should
>>>I
>>> >have to do that to bleed the brakes? I could find no hydraulic
>>>schematic
>>> >in the Bentley, but assume this is a dual diagonal braking system.
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